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  • ActiveMQ - "Cannot send, channel has already failed" every 2 seconds?

    - by quanta
    ActiveMQ 5.7.0 In the activemq.log, I'm seeing this exception every 2 seconds: 2013-11-05 13:00:52,374 | DEBUG | Transport Connection to: tcp://127.0.0.1:37501 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) Due to this keyword InactivityIOException, the first thing comes to my mind is InactivityMonitor, but the strange thing is MaxInactivityDuration=30000: 2013-11-05 13:11:02,672 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-2 Moreover, I also didn't see something like this: No message received since last read check for ... or: Channel was inactive for too (30000) long Do a netstat, I see these connections in TIME_WAIT state: tcp 0 0 127.0.0.1:38545 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38544 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38522 127.0.0.1:61616 TIME_WAIT - Here're the output when running tcpdump: Internet Protocol Version 4, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1 (127.0.0.1) Version: 4 Header length: 20 bytes Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport)) 0000 00.. = Differentiated Services Codepoint: Default (0x00) .... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00) Total Length: 296 Identification: 0x7b6a (31594) Flags: 0x02 (Don't Fragment) 0... .... = Reserved bit: Not set .1.. .... = Don't fragment: Set ..0. .... = More fragments: Not set Fragment offset: 0 Time to live: 64 Protocol: TCP (6) Header checksum: 0xc063 [correct] [Good: True] [Bad: False] Source: 127.0.0.1 (127.0.0.1) Destination: 127.0.0.1 (127.0.0.1) Transmission Control Protocol, Src Port: 61616 (61616), Dst Port: 54669 (54669), Seq: 1, Ack: 2, Len: 244 Source port: 61616 (61616) Destination port: 54669 (54669) [Stream index: 11] Sequence number: 1 (relative sequence number) [Next sequence number: 245 (relative sequence number)] Acknowledgement number: 2 (relative ack number) Header length: 32 bytes Flags: 0x018 (PSH, ACK) 000. .... .... = Reserved: Not set ...0 .... .... = Nonce: Not set .... 0... .... = Congestion Window Reduced (CWR): Not set .... .0.. .... = ECN-Echo: Not set .... ..0. .... = Urgent: Not set .... ...1 .... = Acknowledgement: Set .... .... 1... = Push: Set .... .... .0.. = Reset: Not set .... .... ..0. = Syn: Not set .... .... ...0 = Fin: Not set Window size value: 256 [Calculated window size: 32768] [Window size scaling factor: 128] Checksum: 0xff1c [validation disabled] [Good Checksum: False] [Bad Checksum: False] Options: (12 bytes) No-Operation (NOP) No-Operation (NOP) Timestamps: TSval 2304161892, TSecr 2304161891 Kind: Timestamp (8) Length: 10 Timestamp value: 2304161892 Timestamp echo reply: 2304161891 [SEQ/ACK analysis] [Bytes in flight: 244] Constrained Application Protocol, TID: 240, Length: 244 00.. .... = Version: 0 ..00 .... = Type: Confirmable (0) .... 0000 = Option Count: 0 Code: Unknown (0) Transaction ID: 240 Payload Content-Type: text/plain (default), Length: 240, offset: 4 Line-based text data: text/plain [truncated] \001ActiveMQ\000\000\000\t\001\000\000\000<DE>\000\000\000\t\000\fMaxFrameSize\006\177<FF><FF><FF><FF> <FF><FF><FF>\000\tCacheSize\005\000\000\004\000\000\fCacheEnabled\001\001\000\022SizePrefixDisabled\001\000\000 MaxInactivityDurationInitalDelay\006\ It is very likely a tcp port check. This is what I see when trying telnet from another host: 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: java.io.EOFException | org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ Transport: tcp:///10.8.20.9:46775@61616 java.io.EOFException at java.io.DataInputStream.readInt(DataInputStream.java:375) at org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:275) at org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:229) at org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:221) at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:204) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Unregistering MBean org.apache.activemq:BrokerName=localhost,Type=Connection,ConnectorName=ope nwire,ViewType=address,Name=tcp_//10.8.20.9_46775 | org.apache.activemq.broker.jmx.ManagementContext | ActiveMQ Transport: tcp:/ //10.8.20.9:46775@61616 2013-11-05 16:12:41,073 | DEBUG | Stopping connection: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Stopping transport tcp:///10.8.20.9:46775@61616 | org.apache.activemq.transport.tcp.TcpTranspo rt | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Initialized TaskRunnerFactory[ActiveMQ Task] using ExecutorService: java.util.concurrent.Threa dPoolExecutor@23cc2a28 | org.apache.activemq.thread.TaskRunnerFactory | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Closed socket Socket[addr=/10.8.20.9,port=46775,localport=61616] | org.apache.activemq.transpo rt.tcp.TcpTransport | ActiveMQ Task-1 2013-11-05 16:12:41,074 | DEBUG | Forcing shutdown of ExecutorService: java.util.concurrent.ThreadPoolExecutor@23cc2a28 | org.apache.activemq.util.ThreadPoolUtils | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Stopped transport: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Connection Stopped: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,902 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-5 So the question is: how can I find out the process that is trying to connect to my ActiveMQ (from localhost) every 2 seconds?

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  • Combining HBase and HDFS results in Exception in makeDirOnFileSystem

    - by utrecht
    Introduction An attempt to combine HBase and HDFS results in the following: 2014-06-09 00:15:14,777 WARN org.apache.hadoop.hbase.HBaseFileSystem: Create Dir ectory, retries exhausted 2014-06-09 00:15:14,780 FATAL org.apache.hadoop.hbase.master.HMaster: Unhandled exception. Starting shutdown. java.io.IOException: Exception in makeDirOnFileSystem at org.apache.hadoop.hbase.HBaseFileSystem.makeDirOnFileSystem(HBaseFile System.java:136) at org.apache.hadoop.hbase.master.MasterFileSystem.checkRootDir(MasterFi leSystem.java:428) at org.apache.hadoop.hbase.master.MasterFileSystem.createInitialFileSyst emLayout(MasterFileSystem.java:148) at org.apache.hadoop.hbase.master.MasterFileSystem.<init>(MasterFileSyst em.java:133) at org.apache.hadoop.hbase.master.HMaster.finishInitialization(HMaster.j ava:572) at org.apache.hadoop.hbase.master.HMaster.run(HMaster.java:432) at java.lang.Thread.run(Thread.java:744) Caused by: org.apache.hadoop.security.AccessControlException: Permission denied: user=hbase, access=WRITE, inode="/":vagrant:supergroup:drwxr-xr-x at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPe rmissionChecker.java:224) at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPe rmissionChecker.java:204) at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermi ssion(FSPermissionChecker.java:149) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(F SNamesystem.java:4891) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(F SNamesystem.java:4873) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkAncestorAcce ss(FSNamesystem.java:4847) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInternal(FS Namesystem.java:3192) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInt(FSNames ystem.java:3156) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirs(FSNamesyst em.java:3137) at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.mkdirs(NameN odeRpcServer.java:669) at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTra nslatorPB.mkdirs(ClientNamenodeProtocolServerSideTranslatorPB.java:419) at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$Cl ientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java:4497 0) at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.cal l(ProtobufRpcEngine.java:453) at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1002) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1752) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1748) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:422) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInforma tion.java:1438) at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1746) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstruct orAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingC onstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:408) at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteExce ption.java:90) at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteExc eption.java:57) at org.apache.hadoop.hdfs.DFSClient.primitiveMkdir(DFSClient.java:2153) at org.apache.hadoop.hdfs.DFSClient.mkdirs(DFSClient.java:2122) at org.apache.hadoop.hdfs.DistributedFileSystem.mkdirs(DistributedFileSy stem.java:545) at org.apache.hadoop.fs.FileSystem.mkdirs(FileSystem.java:1915) at org.apache.hadoop.hbase.HBaseFileSystem.makeDirOnFileSystem(HBaseFile System.java:129) ... 6 more while configuration and system settings are as follows: [vagrant@localhost hadoop-hdfs]$ hadoop fs -ls hdfs://localhost/ Found 1 items -rw-r--r-- 3 vagrant supergroup 1010827264 2014-06-08 19:01 hdfs://localhost/u buntu-14.04-desktop-amd64.iso [vagrant@localhost hadoop-hdfs]$ /etc/hadoop/conf/core-site.xml <configuration> <property> <name>fs.defaultFS</name> <value>hdfs://localhost:8020</value> </property> </configuration> /etc/hbase/conf/hbase-site.xml <configuration> <property> <name>hbase.rootdir</name> <value>hdfs://localhost:8020/hbase</value> </property> <property> <name>hbase.cluster.distributed</name> <value>true</value> </property> </configuration> /etc/hadoop/conf/hdfs-site.xml <configuration> <property> <name>dfs.name.dir</name> <value>/var/lib/hadoop-hdfs/cache</value> </property> <property> <name>dfs.data.dir</name> <value>/tmp/hellodatanode</value> </property> </configuration> NameNode directory permissions [vagrant@localhost hadoop-hdfs]$ ls -ltr /var/lib/hadoop-hdfs/cache total 8 -rwxrwxrwx. 1 hbase hdfs 15 Jun 8 23:43 in_use.lock drwxrwxrwx. 2 hbase hdfs 4096 Jun 8 23:43 current [vagrant@localhost hadoop-hdfs]$ HMaster is able to start if fs.defaultFS property has been commented in core-site.xml NameNode is listening [vagrant@localhost hadoop-hdfs]$ netstat -nato | grep 50070 tcp 0 0 0.0.0.0:50070 0.0.0.0:* LIST EN off (0.00/0/0) tcp 0 0 33.33.33.33:50070 33.33.33.1:57493 ESTA BLISHED off (0.00/0/0) and accessible by navigating to http://33.33.33.33:50070/dfshealth.jsp. Question How to solve makeDirOnFileSystem exception and let HBase connect to HDFS?

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  • Gilda Garretón, a Java Developer and Parallelism Computing Researcher

    - by Yolande
    In a new interview titled “Gilda Garretón, a Java Developer and Parallelism Computing Research,” Garretón shares her first-hand experience developing with Java and Java 7 for very large-scale integration (VLSI) of computer-aided design (CAD). Garretón gives an insightful overview of how Java is contributing to the parallelism development and to the Electric VLSI Design Systems, an open source VLSI CAD application used as a research platform for new CAD algorithms as well as the research flow for hardware test chips.  Garretón considers that parallelism programming is hard and complex, yet important developments are taking place.  "With the addition of the concurrent package in Java SE 6 and the Fork/Join feature in Java SE 7, developers have a chance to rely more on existing frameworks and dedicate more time to the essence of their parallel algorithms." Read the full article here  

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  • What are the ways to start making actual/real-world programs using Java/C++ to excel my Programming Skills?

    - by Umer Hassan
    The programming that we learn at university is not that vast, like those are really small exercises to build our logic, but everyone knows that this will not be the scenario when I'll get out in the market as a professional programmer, I really want to make real life programs which would actual make some impacts and will be useful. Tell me in the light of your experience that how should I start making those programs and polish my self as a professional programmer, if there are any sources available for it then kindly also recommend me those.

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  • OpenGL: Attempt to allocate a texture to big for the current hardware

    - by AnonymousMan
    I'm getting the following error: java.io.IOException: Attempt to allocate a texture to big for the current hardware at org.newdawn.slick.opengl.InternalTextureLoader.getTexture(InternalTextureLoader.java:320) at org.newdawn.slick.opengl.InternalTextureLoader.getTexture(InternalTextureLoader.java:254) at org.newdawn.slick.opengl.InternalTextureLoader.getTexture(InternalTextureLoader.java:200) at org.newdawn.slick.opengl.TextureLoader.getTexture(TextureLoader.java:64) at org.newdawn.slick.opengl.TextureLoader.getTexture(TextureLoader.java:24) The image I'm trying to use is 128x128. System.out.println(GL11.glGetInteger(GL11.GL_MAX_TEXTURE_SIZE)); I get: 32. 32??!! My graphics card is AMD Radeon HD 7970M with 2048 MB GDDR5 RAM, I can run all the latest games in 1080p and 60fps with no problem, and those textures sure as hell doesn't look like they are 32x32 pixels to me! How can I fix this? -- Edit: Here's the chaos code I use to init OpenGL: Display.setDisplayMode(new DisplayMode(500,500)); Display.create(); if (!GLContext.getCapabilities().OpenGL11) { throw new Exception("OpenGL 1.1 not supported."); } Display.setTitle("Game"); glMatrixMode(GL_PROJECTION); glLoadIdentity(); GLU.gluPerspective(45, 1, 0.1f, 5000); Mouse.setGrabbed(true); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glEnable(GL_TEXTURE_2D); glClearColor(0, 0, 0, 0); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LEQUAL); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glEnable(GL_BLEND); glEnable(GL_POINT_SMOOTH); glEnable(GL_LINE_SMOOTH); glEnable(GL_POLYGON_SMOOTH); glEnable(GL_POLYGON_OFFSET_FILL); glShadeModel(GL_SMOOTH); Display is a LWJGL thing, it makes the OpenGL context and the window. Anyway, I don't think there's anything in the init code that can help me but you never know...

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  • Java 7 Adoption at 79%

    - by Henrik Stahl
    According to a recent blog post from the cloud hosting company Jelastic, Java 7 adoption on their platform is now at 79%. While this is a single data point and should not be read too broadly, it does match other indicators we have that Java 7 is picking up, such as uptake among Oracle middleware customers, download statistics and online activity. The spike in adoption in April coincided with the release of JDK 7 Update 4. This is in line with our expectations since that release added Mac OS X support as well as java.com moving to Java 7 as the default download for end-users; two events that marked the maturity of Java 7 to the community. Since the original release of Java 7, Oracle has shipped 7 update releases, added ports to Mac OSX and Linux/ARM and expanded JavaFX to all common desktop platforms.

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  • Is Java viable for serious game development?

    - by tehtros
    Ever since I was a little kid, my dream has been to develop games. Well, now that I am older, more mature, and have some programming experience, I would like to start. However, I would like to turn this into a career. The problem, is that my language of choice is Java. Now, I am not intending this to be a Java vs. C++ question, but rather, is Java an acceptable language for serious game development, instead of lower level languages like C++. By serious, I mean high quality graphics, and being able to play a game with said high quality graphics, without much lag on decent computers. Also, eventually, possible making it to consoles. I have scoured the internet, but there are not very many resources for Java game development, not nearly as many as C++. In fact, most engines are written in C++. Once, I tried to play a made with jMonkeyEngine. The game was terribly slow, to the point where my computer froze. I had no other Java applications running and nothing too resource intensive. Keep in mind, that my computer can play most modern 3D games with ease. So, I am really serious about game development, is Java still a viable choice? I have tried multiple times to learn C++, but I don't really like the language. I don't really know why, but usually, whenever I try to learn, I can never grasp the topics. Also, my most of my friends know Java, and one is even anti-C++, saying that no one knows how to use it right. Then, he goes to say that "there is no right way to use C++, that it can not be used correctly. The nature of the language prevents good code." Also, if I continue to learn and improve Java now, and it turns out that later I am required to learn C++, will making the switch be difficult? So, in short, can Java be taken serious, for serious game development. This includes heavy graphics, fast game play without lag, and possibly, and easy switch to consoles?

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  • Java regex patterns - compile time constants or instance members?

    - by KepaniHaole
    Currently, I have a couple of singleton objects where I'm doing matching on regular expressions, and my Patterns are defined like so: class Foobar { private final Pattern firstPattern = Pattern.compile("some regex"); private final Pattern secondPattern = Pattern.compile("some other regex"); // more Patterns, etc. private Foobar() {} public static Foobar create() { /* singleton stuff */ } } But I was told by someone the other day that this is bad style, and Patterns should always be defined at the class level, and look something like this instead: class Foobar { private static final Pattern FIRST_PATTERN = Pattern.compile("some regex"); private static final Pattern SECOND_PATTERN = Pattern.compile("some other regex"); // more Patterns, etc. private Foobar() {} public static Foobar create() { /* singleton stuff */ } } The lifetime of this particular object isn't that long, and my main reason for using the first approach is because it doesn't make sense to me to hold on to the Patterns once the object gets GC'd. Any suggestions / thoughts?

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  • How I use RegExp in my Java program? [migrated]

    - by MIH1406
    I have the following string examples: 00001 1 12 123 00002 3 7 321 00003 99 23 332 00004 192 50 912 In a separate text file. Numbers are separated by tabs not spaces. I tried to read the file and print each line if it matches a given RegExp, but I could not find the suitable RegExp for these lines. private static void readFile() { String fileName = "processes.lst"; FileReader file = null; String result = ""; try { file = new FileReader(fileName); BufferedReader reader = new BufferedReader(file); String line = null; String regEx = "[0-9]\t[0-9]\t[0-9]\t[0-9]"; while((line = reader.readLine()) != null) { if(line.matches(regEx)) { result += "\n" + line; } } } catch(Exception e) { System.out.println(e.getMessage()); } finally { if(file != null) try { file.close(); } catch(Exception e) { System.out.println(e.getMessage()); } } System.out.println(result); } I ended up without any string being printed!!

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  • Which Game Engine to Use for an Angry Bird style game? [JAVA] [on hold]

    - by Arch1tect
    Our team is building an Angry Bird Style game, and we have only about ten days. The game is a little more complex than Angry Bird because there are two players, they each have a castle with pigs to protect(not destroy:)). And the goal is to destroy the other player's pigs. I wonder what Game Engine would help us finish this game most efficiently. We at least need a physics engine but I guess game engine is more helpful since it usually includes physics engine. Correct me if I'm wrong. (So I'm wondering which game engine I should use, if it's just physics engine, I'll use box2d) Networking may or may not be added later depend on time we have. Thanks in advance for any advice! EDIT: image looks small, I'll add one:

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  • Restful Java based web services in json + html5 and javascript no templates (jsp/jsf/freemarker) aka fat/thick client

    - by Ismail Marmoush
    I have this idea of building a website which service JSON data through restful services framework. And will not use any template engines like jsp/jsf/freemarker. Just pure html5 and Javascript libs. What do you think of the pros and cons of such design ? Just for elaboration and brain storming a friend of mine argued with the following concerns: sounds like gwt this way you won't have any control over you service api for example say you wanna charge the user per request how will you handle it? how will you control your design and themes? what about the 1st request the browser make? not easy with this all of the user's requests will come with "Accept" header "application/json" how will you separate browser from abuser? this way all of your public apis will be used by third party apps abusively and you won't be able to lock it since you won't be able to block the normal user browser We won't use compiled html anyway but may be something like freemarker and in that case you won't expose any of your json resources to the unauthorized user but you will expose all the html since any browser can access them all the well known 1st class services do this can you send me links to what you've read? keep in mind the DOM based XSS it will be a nightmare ofc, if what you say is applicable.

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  • JavaOne - Java SE Embedded Booth - Servergy Micro Server

    - by David Clack
    Hi All,  So it's been awhile, I've been working with all the ARM and Power Architecture partners we have now on testing Java SE Embedded. We will have a Java SE Embedded for ARM and PPC at Java One next week, I'll be bringing in some of the great ARM and PPC systems to demonstrate.  The first system I'd like to tell you about is a really cool 8 core Power Architecture Micro Server from a company in Dallas called Servergy. Java One will be it's first public outing, Bill Mapp the CEO will be doing a talk at the Java Embedded @ JavaOne conference in the Hotel Nikko, right next door to the JavaOne show in the Hilton. To read more about Servergy https://www.linux.com/news/enterprise/cloud-computing/641488-linux-based-servergy-advances-data-center-efficiency http://www.servergy.com/ If you are registered at JavaOne you can come over to the Java Embedded @ JavaOne for $100 Come see us in booth 5605 See you there Dave

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  • How are Java ByteBuffer's limit and position variable's updated?

    - by Dummy Derp
    There are two scenarios: writing and reading Writing: Whenever I write something to the ByteBuffer by calling its put(byte[]) method the position variable is incremented as: current position + size of byte[] and limit stays at the max. If, however, I put the data in a view buffer then I will have to, manually, calculate and update the position Before I call the write(ByteBuffer) method of the channel to write something, I will have to flip() the Bytebuffer so that position points to zero and limit points to the last byte that was written to the ByteBuffer. Reading: Whenever I call the read(ByteBuffer) method of a channel to read something, the position variable stays at 0 and the limit variable of the ByteBuffer points to the last byte that was read. So, if the ByteBuffer is smaller than the file being read, the limit variable is pushed to max This means that the ByteBuffer is already flipped and I can proceed to extracting the values from the ByteBuffer. Please, correct me where I am wrong :)

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  • How to effectively design a piece of software

    - by ti83plus
    Im a compsci student and ive got some experience in various languages and paradigms c/java/python/ruby/html/css/scheme/sql/asp(classic). I realise that i want to have some software in my portfolio for future job hunting even tho i still have 2 years left of my education. Ive got a pretty good idea of what i want to make, its a webapp. Most shops around here are either .net or java and since i know java best and dont have access to ms developer tools im thinking i should go with java. Even tho i feel i know the principles of OOP pretty good ive got no clue how to go from my idea to a working solution. Where can i access information about designing the underlying architechture of my solution? Also i would like to know what other technologies i should train on, my current list includes javascript(and possibly a javascript library) some sort of java web framework tips are appreciated. I would like to add support for android/iphone apps in the future and this is something i have to take into account when designing the app. I have done a course on software engineering but i found this to be more centered around project management ideas then the actual design and implementation. So i would like tips on technologies i should focus on to get the most out of my time without the massive overhead of huge config processes but at the same time keep my project viable in a business sense, so that i use technologies that are relevant for business (java developer jobs). And i would also like tips on where i can learn more about the design process around a software project, i will be working mostly alone. But i find the approach ive used up until now (start coding and figure it out as you go) wont suffice.

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  • Where can I find a package for "project looking Glass"? ("The Java desktop")

    - by Alvar
    Hi, I really really want to find this package. Because after I saw the youtube clip I realized it's just one of those things I must have done before I die. This tutorial would be great if the repository were online. My question is: Where can I find the file, and how can I install it without changing my current desktop? The project was called "project looking glass" and was released in 2007. It is now an "inactive open source project", according to its Wikipedia article. @Takkat found this VERY good live cd, hope it works.

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  • Can you shade a specific section of a sprite? If so, how? [Java]

    - by l5p4ngl312
    I have been working on an isometric minecraft-esque game engine for a strategy game I plan on making. As you can see, it really needs some sort of shading. It is difficult to distinguish between separate elevations when the camera is facing away from the slope because everything is the same shade. So my question is: can I shade just a specific section of a sprite? All of those blocks are just sprites, so if I shaded the entire image, it would shade the whole block. I am using LWJGL. Heres a link to a screenshot from the engine: http://i44.tinypic.com/qxqlix.jpg

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  • When to use functional programming approach and when not? (in Java)

    - by john smith optional
    let's assume I have a task to create a Set of class names. To remove duplication of .getName() method calls for each class, I used org.apache.commons.collections.CollectionUtils and org.apache.commons.collections.Transformer as follows: Snippet 1: Set<String> myNames = new HashSet<String>(); CollectionUtils.collect( Arrays.<Class<?>>asList(My1.class, My2.class, My3.class, My4.class, My5.class), new Transformer() { public Object transform(Object o) { return ((Class<?>) o).getName(); } }, myNames); An alternative would be this code: Snippet 2: Collections.addAll(myNames, My1.class.getName(), My2.class.getName(), My3.class.getName(), My4.class.getName(), My5.class.getName()); So, when using functional programming approach is overhead and when it's not and why? Isn't my usage of functional programming approach in snippet 1 is an overhead and why?

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  • Why would Java app make RPC call to itself?

    - by amphibient
    I am working with a multithreaded homegrown multi-module app in my new job. We use the the Thrift protocol to communicate RPC calls between different stand-alone applications in a distributed system. One of them listens on multiple ports and I just noticed that it actually makes an RPC call to itself from one thread invoked from one socket it listens to (web service call) to another port within the same app. I verified that it could accomplish the same thing if it just went and directly called the method that the remote procedure ultimately invokes as it is all within the same application, same JVM. To make it even more mysterious, the call is completely synchronous, i.e. no callbacks involved. The first thread totally sits and waits until it makes a call across the wire to itself and comes back. Now, I am perplexed why anybody would do it this way. It seems like calling somebody on the phone that sits in the same room as you do. Can anybody provide an explanation why the developer before me would come up with the above mentioned model? Maybe there is a reason and I am missing something.

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  • Can I use one set of images to represent multiple sprites in Java?

    - by mal
    I've got a game that has 3 basic sprites, at the moment I'm loading 8 images into each sprite for animating. Each character class has a sprite object. if I've got 10 characters on screen at once then that's 80 images loaded in to memory. Can I make a central sprite class that only holds 8 images for each of the 3 sprites, then get the character objects to request the relevant images from the central sprite class, thereby massively reducing the memory required for the images?

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  • Traverse tree with results. Maybe type in Java?

    - by Angelo.Hannes
    I need to check a tree's node state. It can either be OK or NOT_OK. But that state is dependent on its children. So for a node to be OK, every of its children needs to be OK. If one or more of its children is NOT_OK the whole node is NOT_OK. To determine the state of a node I need to aggregate some properties of the node. So I thought of two possible implementations. And they are more or less covered in this question: Why is Option/Maybe considered a good idea and checked exceptions are not? Exception I could pass the properties up the recursion path, and throw an exception if something went wrong. Maybe I implement an Maybe type and let it either hold an error or the aggregated properties. Maybe it is more an Either. I tend towards the last option. And I'm thinking of an enum with two objects. Where I can additionally set those aggregated properties. Am I on the right track? I'm not familiar with the new JDK8 functional stuff. But I'm stuck on JDK7 anyway, so please focus on JDK7.

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  • 1Z0-899/OCPJWCD 6 Preparation [closed]

    - by Msaleh
    I am preparing for the exam 1Z0-899/OCPJWCD 6 and I have some questions about the preparation: Book: the only good book I can find for now is the Head First Servlet JSP, Second Edition, but it's mostly for the Java EE 5, so are there any books for Java EE 6? Advises from the people passed the exam: can anyone from the people who passed the exams give me some feedback about the exam, and how he prepared for the exam?

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  • Java Embedded @ JavaOne Toolkit

    - by Tori Wieldt
    Java Embedded @ JavaOne provides business decision makers, technical leaders, and ecosystem partners information about Java Embedded technologies and new business opportunities.  From the enterprise business world to the consumer arena, smart meters, automated buildings, and context-aware medical devices can provide information that drive value for businesses and consumers. Java Embedded @ JavaOne will held Wednesday, Oct. 3th and Thursday, Oct. 4th in San Francisco at the Hotel Nikko (during JavaOne). If you have already registered, you can use the Java Embedded @ JavaOne Toolkit to let people know you are attending, to enhanced your blog, and to generate awareness, enthusiasm, and participation. There are banners and buttons, a list of High-Level Benefits of Attending Java Embbeded @ JavaOne, Sample E-Mail Copy, and more. There is also a Toolkit for Partners, Sponsors and Exhibitors. Check out the Java Embbed @ JavaOne Toolkits!

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  • Where will the image be saved? [closed]

    - by Dummy Derp
    import java.awt.Dimension; import java.awt.Rectangle; import java.awt.Robot; import java.awt.Toolkit; import java.awt.image.BufferedImage; import javax.imageio.ImageIO; import java.io.File; ... public void captureScreen(String fileName) throws Exception { Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); Rectangle screenRectangle = new Rectangle(screenSize); Robot robot = new Robot(); BufferedImage image = robot.createScreenCapture(screenRectangle); ImageIO.write(image, "png", new File(fileName)); } ... Going over this code I found on the internet. I got everything except the part where file is created. In what format file name should be? Should it be C:/myFolder/myImage.png" or just myImage.png and where will it be saved? Here is what docs say: File public File(String pathname) Creates a new File instance by converting the given pathname string into an abstract pathname. If the given string is the empty string, then the result is the empty abstract pathname. Parameters: pathname - A pathname string Throws: NullPointerException - If the pathname argument is null

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  • What's your advice in getting Oracle Certified Professional Java Programmer certificate?

    - by den-javamaniac
    Hi. I'm intending to get the certification but not completely sure how to time effectively prepare myself. So I'm wondering if I can be advised on the matter, in particular I would like next questions to be answered: - What the basic learning/practicing plan should look like? - What book (set of books) should be considered? - What practical exercises should be performed? NOTE: I've got several years of corporate experience (mostly web apps, though), but I want to be 100% sure I'll pass the test (that's the reason the issue is raised).

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  • Are there any good Java/JVM libraries for my Expression Tree architecture?

    - by Snuggy
    My team and I are developing an enterprise-level application and I have devised an architecture for it that's best described as an "Expression Tree". The basic idea is that the leaf nodes of the tree are very simple expressions (perhaps simple values or strings). Nodes closer to the trunk will get more and more complex, taking the simpler nodes as their inputs and returning more complex results for their parents. Looking at it the other way, the application performs some task, and for this it creates a root expression. The root expression divides its input into smaller units and creates child expressions, which when evaluated it can use to build it's own result. The subdividing process continues until the simplest leaf nodes. There are two very important aspects of this architecture: It must be possible to manipulate nodes of the tree after it is built. The nodes may be given new input values to work with and any change in result for that node needs to be propagated back up the tree to the root node. The application must make best use of available processors and ultimately be scalable to other computers in a grid or in the cloud. Nodes in the tree will often be updating concurrently and notifying other interested nodes in the tree when they get a new value. Unfortunately, I'm not at liberty to discuss my actual application, but to aid understanding a little bit, you might imagine a kind of spreadsheet application being implemented with a similar architecture, where changes to cells in the table are propagated all over the place to other cells that need the result. The spreadsheet could get so massive that applying multi-core multi-computer distributed system to solve it would be of benefit. I've got my prototype "Expression Engine" working nicely on a single multi-core PC but I've started to run into a few concurrency issues (as expected because I haven't been taking too much care so far) so it's now time to start thinking about migrating the Engine to a more robust library, and that leads to a number of related questions: Is there any precedent for my "Expression Tree" architecture that I could research? What programming concepts should I consider. I realise this approach has many similarities to a functional programming style, and I'm already aware of the concepts of using futures and actors. Are there any others? Are there any languages or libraries that I should study? This question is inspired by my accidental discovery of Scala and the Akka library (which has good support for Actors, Futures, Distributed workloads etc.) and I'm wondering if there is anything else I should be looking at as well?

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