Generates Java Strings with the same hashCode.

StringHashCollisionGenerator.java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class StringHashCollisionGenerator {

    public static void main(String[] args) {
        if (args.length != 1) {
            printUsage();
            System.exit(1);
        }
        int desiredRecords = Integer.valueOf(args[0]);
        if (desiredRecords < 2) {
            printUsage();
            System.exit(1);
        }

        List<String> strings = new ArrayList<String>(Arrays.asList("Aa", "BB"));
        List<String> temp = new ArrayList<String>();

        complete:
        for (int i = 0; i < 5; i++) {
            int size = strings.size();
            temp = new ArrayList<String>(size*size);
            int count = 0;
            for (String s : strings) {
                for (String t : strings) {
                    if (count == desiredRecords) break complete;
                    temp.add(s+t);
                    count++;
                }
            }
            strings = temp;
        }
        strings = temp;

        for (String s : strings)
            System.out.println(s);
    }

    private static void printUsage() {
        System.err.println("Usage: [number of Strings (2^1-2^32]");
    }
}