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  • Using Threads to Handle Sockets

    - by user340468
    I am working on a java program that is essentially a chat room. This is an assignment for class so no code please, I am just having some issues determining the most feasible way to handle what I need to do. I have a server program already setup for a single client using threads to get the data input stream and a thread to handle sending on the data output stream. What I need to do now is create a new thread for each incoming request. My thought is to create a linked list to contain either the client sockets, or possibly the thread. Where I am stumbling is figuring out how to handle sending the messages out to all the clients. If I have a thread for each incoming message how can I then turn around and send that out to each client socket. I'm thinking that if I had a linkedlist of the clientsockets I could then traverse the list and send it out to each one, but then I would have to create a dataoutputstream each time. Could I create a linkedlist of dataoutputstreams? Sorry if it sounds like I'm rambling but I don't want to just start coding this, it could get messy without a good plan. Thanks!

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  • "pseudo-atomic" operations in C++

    - by dan
    So I'm aware that nothing is atomic in C++. But I'm trying to figure out if there are any "pseudo-atomic" assumptions I can make. The reason is that I want to avoid using mutexes in some simple situations where I only need very weak guarantees. 1) Suppose I have globally defined volatile bool b, which initially I set true. Then I launch a thread which executes a loop while(b) doSomething(); Meanwhile, in another thread, I execute b=true. Can I assume that the first thread will continue to execute? In other words, if b starts out as true, and the first thread checks the value of b at the same time as the second thread assigns b=true, can I assume that the first thread will read the value of b as true? Or is it possible that at some intermediate point of the assignment b=true, the value of b might be read as false? 2) Now suppose that b is initially false. Then the first thread executes bool b1=b; bool b2=b; if(b1 && !b2) bad(); while the second thread executes b=true. Can I assume that bad() never gets called? 3) What about an int or other builtin types: suppose I have volatile int i, which is initially (say) 7, and then I assign i=7. Can I assume that, at any time during this operation, from any thread, the value of i will be equal to 7? 4) I have volatile int i=7, and then I execute i++ from some thread, and all other threads only read the value of i. Can I assume that i never has any value, in any thread, except for either 7 or 8? 5) I have volatile int i, from one thread I execute i=7, and from another I execute i=8. Afterwards, is i guaranteed to be either 7 or 8 (or whatever two values I have chosen to assign)?

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  • Adding and sorting a linked list in C

    - by user1202963
    In my assignment, I have to write a function that takes as arguments a pointer to a "LNode" structure and an integer argument. Then, I have to not only add that integer into the linked list, but also put place it so that the list is in proper ascending order. I've tried several various attempts at this, and this is my code as of posting. LNode* AddItem(LNode *headPtr, int newItem) { auto LNode *ptr = headPtr; ptr = malloc(sizeof(LNode)); if (headPtr == NULL) { ptr->value = newItem; ptr->next = headPtr; return ptr; } else { while (headPtr->value > newItem || ptr->next != NULL) { printf("While\n"); // This is simply to let me know how many times the loop runs headPtr = headPtr->next; } ptr->value = newItem; ptr->next = headPtr; return ptr; } } // end of "AddItem" When I run it, and try to insert say a 5 and then a 3, the 5 gets inserted, but then the while loop runs once and I get a segmentation fault. Also I cannot change the arguments as it's part of a skeletal code for this project. Thanks to anyone who can help. If it helps this is what the structure looks like typedef struct LNode { int value; struct LNode *next; } LNode;

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  • implementing interface

    - by 1ace1
    hello guys so i have this assignment that i need to implement interface to go over an ArrayList and sort it (ascending or descnding).I dont want "the" answer i just need some suggestions on my approach and why i get this error Exception in thread "main" java.lang.ClassCastException: Week7.Check cannot be cast to java.lang.Comparable at java.util.Arrays.mergeSort(Unknown Source) at java.util.Arrays.sort(Unknown Source) at java.util.Collections.sort(Unknown Source) at Week7.TestCheck.main(TestCheck.java:18) This is how i did it: comparable had one method called public int compairTo(Object o) public class Check implements comparable { private Integer checkNumber; public Check(Integer newCheckNumber) { setCheckNumber(newCheckNumber); } public String toString() { return getCheckNumber().toString(); } public void setCheckNumber(Integer checkNumber) { this.checkNumber = checkNumber; } public Integer getCheckNumber() { return checkNumber; } @Override public int compairTo(Object o) { Check compair = (Check)o; int result = 0; if (this.getCheckNumber() > compair.getCheckNumber()) result = 1; else if(this.getCheckNumber() < compair.getCheckNumber()) result = -1; return result; } } in my main i had this import java.util.ArrayList; import java.util.Collections; public class TestCheck { public static void main(String[] args) { ArrayList checkList = new ArrayList(); checkList.add(new Check(445)); checkList.add(new Check(101)); checkList.add(new Check(110)); checkList.add(new Check(553)); checkList.add(new Check(123)); Collections.sort(checkList); for (int i =0; i < checkList.size(); i++){ System.out.println(checkList.get(i)); } } }

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  • Planning a programming project by example (C# or C++)

    - by Lunan
    I am in the last year of undergraduate degree and i am stumped by the lack of example in c++ and c# large project in my university. All the mini project and assignment are based on text based database, which is so inefficient, and console display and command, which is frustrating. I want to develop a complete prototype of corporate software which deals in Inventory, Sales, Marketing, etc. Everything you would usually find in SAP. I am grateful if any of you could direct me to a books or article or sample program. Some of the question are : How to plan for this kind of programming? should i use the concept of 1 object(such as inventory) have its own process and program and have an integrator sit for all the program, or should i integrate it in 1 big program? How to build and address a database? i have little bit knowledge in database and i know SQL but i never address database in a program before. Database are table, and how do you suppose to represent a table in a OOP way? For development type, which is better PHP and C++ or C# and ASP.NET? I am planning to use Web Interface to set form and information, but using a background program to handle the compute. .NET is very much integrated and coding should be much faster, but i really wonder about performance if compared to PHP and C++ package thank you for the info

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  • How to import properties of an external API into Script#

    - by AndrewDotHay
    I'm using Script# inside Visual Studio 2010 to import the API for the HTML5 Canvas element. Its working great for things like FillRect(), MoveTo(), LineTo() and so on. I've declared the following interface and then I can code against it in C#. Then, Script# converts it to JavaScript nicely. public interface CanvasContext { void FillRect(int x, int y, int width, int height); void BeginPath(); void MoveTo(int x, int y); void LineTo(int x, int y); void Stroke(); void FillText(string text, int x, int y); } I want to include the StrokeStyle property that takes a simple string. The following interface definition produces a prefix in the JavaScript, which causes it to fail. string StrokeStyle { get; set; } string Font { get; set; } The previous property will create this JavaScript: ctx.set_strokeStyle('#FF0'); How can I get Script# to generate the simple assignment properties of the canvas context without the get_/set_ prefix?

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  • Which of the following Java coding fragments is better?

    - by Simon
    This isn't meant to be subjective, I am looking for reasons based on resource utilisation, compiler performance, GC performance etc. rather than elegance. Oh, and the position of brackets doesn't count, so no stylistic comments please. Take the following loop; Integer total = new Integer(0); Integer i; for (String str : string_list) { i = Integer.parse(str); total += i; } versus... Integer total = 0; for (String str : string_list) { Integer i = Integer.parse(str); total += i; } In the first one i is function scoped whereas in the second it is scoped in the loop. I have always thought (believed) that the first one would be more efficient because it just references an existing variable already allocated on the stack, whereas the second one would be pushing and popping i each iteration of the loop. There are quite a lot of other cases where I tend to scope variables more broadly than perhaps necessary so I thought I would ask here to clear up a gap in my knowledge. Also notice that assignment of the variable on initialisation either involving the new operator or not. Do any of these sorts of semi-stylistic semi-optimisations make any difference at all?

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  • Problem in homemade function to merge objects

    - by Eric
    I'm trying to make a function that merges arrays. The reason is, I have a function that supposed to get the settings of an entity, and merge them with the global defaults. //So for example, let's say globalOptions is something like this var globalOptions={opt1:'foo',opt2:'something'}; //and this is entityOptions var entityOptions={opt1:'foofoo',opt2:null}; The only difference is it has objects in objects and objects in objects in objects, so what I made was a function that loops through all objects, thinking I would later, easily be able to loop through it all. Please ignore the array thing. That is defected, but unneeded. function loopObj(obj, call, where, objcall, array) { if ($.isArray(obj) || $.isPlainObject(obj)) { for (i in obj) { if ($.isArray(obj)) { if (array) { loopObj(obj[i], call, where[where.length] = i, true); if (objcall) { call(obj[i],where,true); } } else { loopObj(obj[i], call, where+'['+i+']', false); if (objcall) { call(obj[i],where,true); } } } else { if (array) { loopObj(obj[i], call, where[where.length] = parseInt(i), true); if (objcall) { call(obj[i],where,true); } } else { loopObj(obj[i], call, where+'[\''+i+'\']', false); if (objcall) { call(obj[i],where,true); } } } } } else { return call(obj,where); } } Then I made this program to convert it: function mergeObj(a,b) { temp.retd = new Object(); loopObj(a,function (c,d) { if (c) { eval(d.replace('%par%','temp.retd'))=c; } else { eval(d.replace('%par%','temp.retd'))=eval(d.replace('%par%','b')); } },'%par%', true); return temp.retd(); } I get the error: Uncaught ReferenceError: Invalid left-hand side in assignment (anonymous function)base.js:51 loopObjbase.js:40 loopObjbase.js:31 mergeObjbase.js:46 (anonymous function)base.js:72 I know what it means, the eval returns an anonomys variable (copy of the variable), so I can't set it, only get it.

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  • Singleton pattern in C++

    - by skydoor
    I have a question about the singleton pattern. I saw two cases concerning the static member in the singleton class. First it is an object, like this class CMySingleton { public: static CMySingleton& Instance() { static CMySingleton singleton; return singleton; } // Other non-static member functions private: CMySingleton() {} // Private constructor ~CMySingleton() {} CMySingleton(const CMySingleton&); // Prevent copy-construction CMySingleton& operator=(const CMySingleton&); // Prevent assignment }; One is an pointer, like this class GlobalClass { int m_value; static GlobalClass *s_instance; GlobalClass(int v = 0) { m_value = v; } public: int get_value() { return m_value; } void set_value(int v) { m_value = v; } static GlobalClass *instance() { if (!s_instance) s_instance = new GlobalClass; return s_instance; } }; What's the difference between the two cases? Which one is correct?

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  • Storing multiple discarded datas in a single variable using a string accumulator

    - by dan
    For an assignment for my intro to python course, we are to write a program that generates 100 sets of x,y coordinates. X must be a float between -100.0 and 100.0 inclusive, but not 0. Y is Y = ((1/x) * 3070) but if the absolute value of Y is greater than 100, both numbers must be discarded (BUT STORED) and another set generated. The results must be displayed in a table, and then after the table, the discarded results must be shown. The teacher said we should use a "string accumulator" to store the discarded data. This is what I have so far, and I'm stuck at storing the discarded data. # import random.py import random # import math.py import math # define main def main(): x = random.uniform(-100.0, 100.0) while x == 0: x = random.uniform(-100.0, 100.0) y = ((1/x) * 3070) while math.fabs(y) > 100: xDiscarded = yDiscarded = y = ((1/x) * 3070) As you can see, I run into the problem of when abs(y) 100, I'm not too sure how to store the discarded data and let it accumulate every time abs(y) 100. I'm cool with the data being stored as "351.2, 231.1, 152.2" I just don't know how to turn the variable into a string and store it. We haven't learned arrays yet so I can't do that. Any help would be much appreciated. Thanks!

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  • User input being limited to the alphabet in python

    - by Danger Cat
    I am SUPER new to programming and have my first assignment coming up in python. I am writing a hangman type game, where users are required to guess the word inputted from the other user. I have written most of the code, but the only problem I am having is when users have to input the word, making sure it is only limited to the alphabet. The code I have so far is : word = str.lower(raw_input("Type in your secret word! Shhhh... ")) answer = True while answer == True: for i in range(len(word)): if word[i] not in ("abcdefghijklmnopqrstuvwxyz"): word = raw_input("Sorry, words only contain letters. Please enter a word ") break else: answer = False This works while I input a few tries, but eventually will either exit the loop or displays an error. Is there any easier way to use this? We've really only covered topics up to loops in class, and break and continue are also very new to me. Thank you! (Pardon if the code is sloppy, but as I said I am very new to this....)

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  • CSS working in IE, but not FF

    - by cdotlister
    Hi guys, I have a very simple css file for my Asp.Net MVC application. body { font-family: Arial, Helvetica, sans-serif; font-size: x-small; color: #663300; } input { font-family: Arial, Helvetica, sans-serif; font-size: x-small; background-color: #FFFF99; color: #CC6600; border: 1px solid #808000; } .headerRow { background-color: #FFFFCC; border-style: none none dotted none; border-bottom-width: 1px; border-bottom-color: #800000; font-family: Arial, Helvetica, sans-serif; font-size: x-small; font-weight: bold; text-align: left; vertical-align: middle; text-transform: uppercase; } The Body is working well in both... as is the input. However, the headerRow isn't working in FF, yet works well in IE. Here it is, being used: <table width="700" border="0" cellspacing="1" cellpadding="2"> <tr class="headerRow"> <td> Transaction Date </td> <td> Type </td> <td> Category </td> <td> Budget Assignment </td> <td> Cost Center </td> <td align="right"> Amount </td> </tr> The header row just displays as normal body text though...

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  • In C# should I reuse a function / property parameter to compute cleaner temporary value or create a

    - by Hamish Grubijan
    The example below may not be problematic as is, but it should be enough to illustrate a point. Imagine that there is a lot more work than trimming going on. public string Thingy { set { // I guess we can throw a null reference exception here on null. value = value.Trim(); // Well, imagine that there is so much processing to do this.thingy = value; // That this.thingy = value.Trim() would not fit on one line ... So, if the assignment has to take two lines, then I either have to abusereuse the parameter, or create a temporary variable. I am not a big fan of temporary variables. On the other hand, I am not a fan of convoluted code. I did not include an example where a function is involved, but I am sure you can imagine it. One concern I have is if a function accepted a string and the parameter was "abused", and then someone changed the signature to ref in both places - this ought to mess things up, but ... who would knowingly make such a change if it already worked without a ref? Seems like it is their responsibility in this case. If I mess with the value of value, am I doing something non-trivial under the hood? If you think that both approaches are acceptable, then which do you prefer and why? Thanks.

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  • What is a more "ruby way" to write this code?

    - by steadfastbuck
    This was a homework assignment for my students (I am a teaching assistant) in c and I am trying to learn Ruby, so I thought I would code it up. The goal is to read integers from a redirected file and print some simple information. The first line in the file is the number of elements, and then each integer resides on its own line. This code works (although perhaps inefficiently), but how can I make the code more Ruby-like? #!/usr/bin/ruby -w # first line is number of inputs (Don't need it) num_inputs = STDIN.gets.to_i # read inputs as ints h = Hash.new STDIN.each do |n| n = n.to_i h[n] = 1 unless h[n] and h[n] += 1 end # find smallest mode h.sort.each do |k,v| break puts "Mode is: #{k}", "\n" if v == h.values.max end # mode unique? v = h.values.sort print "Mode is unique: " puts v.pop == v.pop, "\n" # print number of singleton odds, # odd elems repeated odd number times in desc order # even singletons in desc order odd_once = 0 odd = Array.new even = Array.new h.each_pair do |k, v| odd_once += 1 if v == 1 and k.odd? odd << k if v.odd? even << k if v == 1 and k.even? end puts "Number of elements with an odd value that appear only once: #{odd_once}", "\n" puts "Elements repeated an odd number of times:" puts odd.sort.reverse, "\n" puts "Elements with an even value that appear exactly once:" puts even.sort.reverse, "\n" # print fib numbers in the hash class Fixnum def is_fib? l, h = 0, 1 while h <= self return true if h == self l, h = h, l+h end end end puts "Fibonacci numbers:" h.keys.sort.each do |n| puts n if n.is_fib? end

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  • How to randomly assign a partner?

    - by David
    I asked a question some time ago about creating a random circular partner assignment using php and mysql. This is a related issue. I am working from the following code to try to give two users new, randomly selected partners: $q = "SELECT user_id FROM users WHERE partner='$quit_partner' AND status='1'"; $r = mysqli_query ($dbc, $q) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($dbc)); while ($row = mysqli_fetch_array($r)) { $users[] = $row[0]; } $current = end($users); $partners = array(); foreach ($users as $user) { $partners[$user] = $current; $current = $user; $q = "UPDATE users SET partner='{$partners[$user]}' WHERE user_id='{$user}'"; mysqli_query ($dbc, $q) or trigger_error("Query: $q\n<br />MySQL Error: " . mysqli_error($dbc)); } Basically, a particular user (lets say user #4) quits the activity, leaving multiple other users without a partner (hypothetically, users # 5,6,7). I need to find out who those users are, hence the first query. Once I find them, I throw them into an array. Then comes the difficult part. I want those newly partnerless users (5,6,7) to be randomly assigned new partners from everyone in the table. The current code is flawed in that it only assigns the newly partnerless users eachother. Thanks for your help.

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  • Dynamic Array of Objects Sans Vector Class

    - by Connor Black
    I am doing a homework assignment for my summer OO class and we need to write two classes. One is called Sale and the other is called Register. I've written my Sale class; here's the .h file: enum ItemType {BOOK, DVD, SOFTWARE, CREDIT}; class Sale { public: Sale(); // default constructor, // sets numerical member data to 0 void MakeSale(ItemType x, double amt); ItemType Item(); // Returns the type of item in the sale double Price(); // Returns the price of the sale double Tax(); // Returns the amount of tax on the sale double Total(); // Returns the total price of the sale void Display(); // outputs sale info private: double price; // price of item or amount of credit double tax; // amount of sales tax double total; // final price once tax is added in. ItemType item; // transaction type }; For the Register class we need to include a dynamic array of Sale objects in our member data. We cannot use the vector class. How is this done? Here's my 'Register' '.h' class Register{ public: Register(int ident, int amount); ~Register(); int GetID(){return identification;} int GetAmount(){return amountMoney;} void RingUpSale(ItemType item, int basePrice); void ShowLast(); void ShowAll(); void Cancel(); int SalesTax(int n); private: int identification; int amountMoney; };

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  • reading keyboard input without "consuming" it in x86 assembly

    - by Bob
    Ok so here the deal: I have an assignment regarding DOS and interrupts: I need to write a sort of key-logger function that can be called from C code. what it means is a c program would call an assembly function called startlog that would indicate to start logging the keys pressed until a function called endlog is called. the logging should work like this: write the ascii value of any key pressed without disturbing the C code between startlog and endlog, meaning that if the C code also needs to read the input (let's say by scanf, it would work ok). I managed to write the logger by changing the interrupt vector 9th entry (interrupt for keyboard press) to a function I wrote that writes the values to a file, and it works fine. however the C code does not get the input. Basically what i did is read the key pressed using int 21h, however after reading the ascii value it is "consumed" so I need a way to either simulate the key press again or read the value without "consuming" it so next time a key is read it reads the same key. (I described the code in english because it is long and clumsy assembly code)

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  • Database Tutorial: The method open() is undefined for the type MainActivity.DBAdapter

    - by user2203633
    I am trying to do this database tutorial on SQLite Eclipse: https://www.youtube.com/watch?v=j-IV87qQ00M But I get a few errors at the end.. at db.ppen(); i get error: The method open() is undefined for the type MainActivity.DBAdapter and similar for insert record and close. MainActivity: package com.example.studentdatabase; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import android.app.Activity; import android.app.ListActivity; import android.content.Intent; import android.database.Cursor; import android.os.Bundle; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.Toast; public class MainActivity extends Activity { /** Called when the activity is first created. */ //DBAdapter db = new DBAdapter(this); @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button addBtn = (Button)findViewById(R.id.add); addBtn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent i = new Intent(MainActivity.this, addassignment.class); startActivity(i); } }); try { String destPath = "/data/data/" + getPackageName() + "/databases/AssignmentDB"; File f = new File(destPath); if (!f.exists()) { CopyDB( getBaseContext().getAssets().open("mydb"), new FileOutputStream(destPath)); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } DBAdapter db = new DBAdapter(); //---add an assignment--- db.open(); long id = db.insertRecord("Hello World", "2/18/2012", "DPR 224", "First Android Project"); id = db.insertRecord("Workbook Exercises", "3/1/2012", "MAT 100", "Do odd numbers"); db.close(); //---get all Records--- /* db.open(); Cursor c = db.getAllRecords(); if (c.moveToFirst()) { do { DisplayRecord(c); } while (c.moveToNext()); } db.close(); */ /* //---get a Record--- db.open(); Cursor c = db.getRecord(2); if (c.moveToFirst()) DisplayRecord(c); else Toast.makeText(this, "No Assignments found", Toast.LENGTH_LONG).show(); db.close(); */ //---update Record--- /* db.open(); if (db.updateRecord(1, "Hello Android", "2/19/2012", "DPR 224", "First Android Project")) Toast.makeText(this, "Update successful.", Toast.LENGTH_LONG).show(); else Toast.makeText(this, "Update failed.", Toast.LENGTH_LONG).show(); db.close(); */ /* //---delete a Record--- db.open(); if (db.deleteRecord(1)) Toast.makeText(this, "Delete successful.", Toast.LENGTH_LONG).show(); else Toast.makeText(this, "Delete failed.", Toast.LENGTH_LONG).show(); db.close(); */ } private class DBAdapter extends BaseAdapter { private LayoutInflater mInflater; //private ArrayList<> @Override public int getCount() { return 0; } @Override public Object getItem(int arg0) { return null; } @Override public long getItemId(int arg0) { return 0; } @Override public View getView(int arg0, View arg1, ViewGroup arg2) { return null; } } public void CopyDB(InputStream inputStream, OutputStream outputStream) throws IOException { //---copy 1K bytes at a time--- byte[] buffer = new byte[1024]; int length; while ((length = inputStream.read(buffer)) > 0) { outputStream.write(buffer, 0, length); } inputStream.close(); outputStream.close(); } public void DisplayRecord(Cursor c) { Toast.makeText(this, "id: " + c.getString(0) + "\n" + "Title: " + c.getString(1) + "\n" + "Due Date: " + c.getString(2), Toast.LENGTH_SHORT).show(); } public void addAssignment(View view) { Intent i = new Intent("com.pinchtapzoom.addassignment"); startActivity(i); Log.d("TAG", "Clicked"); } } DBAdapter code: package com.example.studentdatabase; public class DBAdapter { public static final String KEY_ROWID = "id"; public static final String KEY_TITLE = "title"; public static final String KEY_DUEDATE = "duedate"; public static final String KEY_COURSE = "course"; public static final String KEY_NOTES = "notes"; private static final String TAG = "DBAdapter"; private static final String DATABASE_NAME = "AssignmentsDB"; private static final String DATABASE_TABLE = "assignments"; private static final int DATABASE_VERSION = 2; private static final String DATABASE_CREATE = "create table if not exists assignments (id integer primary key autoincrement, " + "title VARCHAR not null, duedate date, course VARCHAR, notes VARCHAR );"; private final Context context; private DatabaseHelper DBHelper; private SQLiteDatabase db; public DBAdapter(Context ctx) { this.context = ctx; DBHelper = new DatabaseHelper(context); } private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { try { db.execSQL(DATABASE_CREATE); } catch (SQLException e) { e.printStackTrace(); } } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data"); db.execSQL("DROP TABLE IF EXISTS contacts"); onCreate(db); } } //---opens the database--- public DBAdapter open() throws SQLException { db = DBHelper.getWritableDatabase(); return this; } //---closes the database--- public void close() { DBHelper.close(); } //---insert a record into the database--- public long insertRecord(String title, String duedate, String course, String notes) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_TITLE, title); initialValues.put(KEY_DUEDATE, duedate); initialValues.put(KEY_COURSE, course); initialValues.put(KEY_NOTES, notes); return db.insert(DATABASE_TABLE, null, initialValues); } //---deletes a particular record--- public boolean deleteContact(long rowId) { return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0; } //---retrieves all the records--- public Cursor getAllRecords() { return db.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, KEY_DUEDATE, KEY_COURSE, KEY_NOTES}, null, null, null, null, null); } //---retrieves a particular record--- public Cursor getRecord(long rowId) throws SQLException { Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, KEY_DUEDATE, KEY_COURSE, KEY_NOTES}, KEY_ROWID + "=" + rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } //---updates a record--- public boolean updateRecord(long rowId, String title, String duedate, String course, String notes) { ContentValues args = new ContentValues(); args.put(KEY_TITLE, title); args.put(KEY_DUEDATE, duedate); args.put(KEY_COURSE, course); args.put(KEY_NOTES, notes); return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0; } } addassignment code: package com.example.studentdatabase; public class addassignment extends Activity { DBAdapter db = new DBAdapter(this); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.add); } public void addAssignment(View v) { Log.d("test", "adding"); //get data from form EditText nameTxt = (EditText)findViewById(R.id.editTitle); EditText dateTxt = (EditText)findViewById(R.id.editDuedate); EditText courseTxt = (EditText)findViewById(R.id.editCourse); EditText notesTxt = (EditText)findViewById(R.id.editNotes); db.open(); long id = db.insertRecord(nameTxt.getText().toString(), dateTxt.getText().toString(), courseTxt.getText().toString(), notesTxt.getText().toString()); db.close(); nameTxt.setText(""); dateTxt.setText(""); courseTxt.setText(""); notesTxt.setText(""); Toast.makeText(addassignment.this,"Assignment Added", Toast.LENGTH_LONG).show(); } public void viewAssignments(View v) { Intent i = new Intent(this, MainActivity.class); startActivity(i); } } What is wrong here? Thanks in advance.

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  • How do I use requestFocus in a Java JFrame GUI?

    - by JohnWong
    I am given an assignment but I am totally new to Java (I have been programming in C++ and Python for two years). So we are doing GUI and basically we extended JFrame and added a couple fields. Say we have a field named "Text 1" and "Text 2". When user presses enter with the cursor in Text 1, move the focus to Text 2. I tried to add private JTextField textfield1() { textfield1 = new JTextField(); textfield1.setPreferredSize(new Dimension(200, 20)); textfield1.addActionListener( new ActionListener() { public void actionPerformed(ActionEvent e) { textfield1text = textfield1.getText().trim(); textfield1.setText(textfield1text); System.out.println(textfield1text); textfield1.requestFocus(); } }); return textfield1; } But that doesn't work at all. I noticed that requestFocus is not recommended, and instead one should use requestFocusWindows. But I tried that too. Upon some readings it seems like I have to do keyboard action and listener? But my teacher said it only requires 1 line...

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  • Query table value aliasing in Oracle SQL

    - by Strata
    I have a homework assignment in SQL for Oracle 10g where I have to apply union to two different select statements, to return two columns. I need the values of each cell under vendor_state to indicate CA and every other value in another state to return "Outside CA", to indicate they're elsewhere. I applied the union and produced the two columns and the listings for CA, but many other state IDs were listed and I couldn't find an explanation for how to change the actual values in the query itself. Eventually, I stumbled on an answer, but I can't explain why this works. The code is as follows: SELECT vendor_name, vendor_state FROM vendors WHERE vendor_state IN 'CA' UNION SELECT vendor_name, 'Outside CA' AS vendor_state FROM vendors WHERE vendor_state NOT IN 'CA' ORDER BY vendor_name This gives me the exact answer I need, but I don't know why the aliasing in the second select statement can behave this way....no explanation is given in my textbook and nothing I've read indicates that column aliasing can be done like this. But, by switching the column name and the alias value, I have replaced the value being returned rather than the column name itself...I'm not complaining about the result, but it would help if I knew how I did it.

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  • Basic SQL Query, I am newbie

    - by user3530547
    I just started my database and query class on Monday. We met on Monday and just went over the syllabus, and on Wednesday the network at school was down so we couldn't even do the power point lecture. Right now I am working on my first homework assignment and I am almost finished but I am having trouble on one question. Here is is... Write a SELECT statement that returns one column from the Customers table named FullName that joins the LastName and FirstName columns. Format the columns with the last name, a comma, a space, and the first name like this: Doe, John Sort the result set by last name in ascending sequence. Return only the contacts whose last name begins with letters from M to Z. Here is what I have so far... USE md0577283 SELECT FirstName,LastName FROM Customers ORDER BY LastName,FirstName My question is how do I format is Lastname, FirstName like the professor wants and how do I only select names M-Z? If someone could point me in the right direction I would greatly appreciate it. Thank you. PS With all do respect, I didn't ask for the answer I asked for a nudge in the right direction so why the down vote guys?

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  • const pod and std::vector

    - by Baz
    To get this code to compile: std::vector<Foo> factory() { std::vector<Foo> data; return data; } I have to define my POD like this: struct Foo { const int i; const int j; Foo(const int _i, const int _j): i(_i), j(_j) {} Foo(Foo& foo): i(foo.i), j(foo.j){} Foo operator=(Foo& foo) { Foo f(foo.i, foo.j); return f; } }; Is this the correct approach for defining a pod where I'm not interested in changing the pod members after creation? Why am I forced to define a copy constructor and overload the assignment operator? Is this compatible for different platform implementations of std::vector? Is it wrong in your opinion to have const PODS like this? Should I just leave them as non-const?

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  • SAS V9.1.3 - Error when combining %INC and CALL EXECUTE

    - by Mark
    Hi, I am getting a resolution error with some SAS v9.1.3 code. Here is some code I want to store in a .txt file (called problem2.txt) and bring into SAS with a %INC %macro email020; %if &email = 1 %then %do; %put THIS RESOLVED AT 1; %end; %else %if &email = 2 %then %do; %put THIS RESOVLED AT 2; %end; %put _user_; %mend email020; %email020; Then this is the main code: filename problem2 'C:\Documents and Settings\Mark\My Documents\problem2.txt'; %macro report1; %let email = 1; %inc problem2; %mend report1; %macro report2 (inc); %let email = 2; %inc problem2; %mend report2; data test; run = 'YES'; run; data _null_; set test; call execute("%report1"); call execute("%report2"); run; The log shows: NOTE: CALL EXECUTE generated line. 1 + %inc problem2; MLOGIC(EMAIL020): Beginning execution. WARNING: Apparent symbolic reference EMAIL not resolved. ERROR: A character operand was found in the %EVAL function or %IF condition where a numeric operand is required. The condition was: &email = 1 ERROR: The macro EMAIL020 will stop executing. MLOGIC(EMAIL020): Ending execution. So the question is why does CALL EXECUTE generate %inc problem2 rather than %report1, causing SAS to miss the assignment and what can I do about it?

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  • Calculating percent "x/y * 100" always results in 0?

    - by Patrick Beninga
    In my assignment i have to make a simple version of Craps, for some reason the percentage assignments always produce 0 even when both variables are non 0, here is the code. import java.util.Random; Header, note the variables public class Craps { private int die1, die2,myRoll ,myBet,point,myWins,myLosses; private double winPercent,lossPercent; private Random r = new Random(); Just rolls two dies and produces their some. public int roll(){ die1 = r.nextInt(6)+1; die2 = r.nextInt(6)+1; return(die1 + die2); } The Play method, this just loops through the game. public void play(){ myRoll = roll(); point = 0; if(myRoll == 2 ||myRoll == 3 || myRoll == 12){ System.out.println("You lose!"); myLosses++; }else if(myRoll == 7 || myRoll == 11){ System.out.println("You win!"); myWins++; }else{ point = myRoll; do { myRoll = roll(); }while(myRoll != 7 && myRoll != point); if(myRoll == point){ System.out.println("You win!"); myWins++; }else{ System.out.println("You lose!"); myLosses++; } } } This is where the bug is, this is the tester method. public void tester(int howMany){ int i = 0; while(i < howMany){ play(); i++; } bug is right here in these assignments statements winPercent = myWins/i * 100; lossPercent = myLosses/i* 100; System.out.println("program ran "+i+" times "+winPercent+"% wins "+ lossPercent+"% losses with "+myWins+" wins and "+myLosses+" losses"); } }

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  • Car Class (first time with classes)

    - by user2967605
    For an assignment I needed to use a class named car and have it display the make and model, and also have the speed increase by 5 when you use accelerate and decrease by 5 when you brake. My teacher helped me along the way but when I got to the end I couldn't get it to run. Could someone correct me and tell my why it's wrong? Imp--------- #include <iostream> #include <string> using namespace std; void accelerate() { int speed; speed = speed + 5; } void brake() { int speed; speed = speed - 5; } Header #include <iostream> #include <string> using namespace std; class car { public: car(int getYear, string getMake); void accelerate(); void brake(); private: int year; string make; int speed; }; CarClass.cpp #include <string> #include "CarClass.h" using namespace std; int main() { car.(2013,"Kia") car.accelerate() car.brake() }

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