Hello ,

I am trying to create an adjacency list to store a graph.The implementation works fine while storing 100,000 records. However,when I tried to store around 1million records I ran into OutofMemory Error :

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOfRange(Arrays.java:3209) at java.lang.String.(String.java:215) at java.io.BufferedReader.readLine(BufferedReader.java:331) at java.io.BufferedReader.readLine(BufferedReader.java:362) at liarliar.main(liarliar.java:39)

Following is my implementation

HashMap<String,ArrayList<String>> adj = new HashMap<String,ArrayList<String>>(num);


        while ((str = in.readLine()) != null)
        {

            StringTokenizer Tok = new StringTokenizer(str);
            name = (String) Tok.nextElement();
            cnt = Integer.valueOf(Tok.nextToken());
            ArrayList<String> templist = new ArrayList<String>(cnt);

            while(cnt>0)
             {
                    templist.add(in.readLine());
                    cnt--;
             }
            adj.put(name,templist);

        } //done creating a adjacency list

I am wondering, if there is any better way to implement the adjacency list. Also, I know number of nodes right in the begining and , in the future I flatten the list as I visit nodes. Any suggestions ?

Thanks