JavaMemory.java

/** Studies Java Memory */
import java.util.*;
import java.io.*;
public class JavaMemory {
  static volatile boolean stop = false;
  public static void main(String[] args) throws Exception { 
    System.out.println("Hope you ran it with -Xmx32m");
    Thread alloc = new Thread(new Allocator());
    alloc.start();
  }
}
class Allocator implements Runnable {
  private final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
  volatile long[] longs = new long[0];
  public void run() {
    while (!JavaMemory.stop) {
      String s = null;
      try {
        s = reader.readLine();
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
      if ("n".equals(s)) {
        //System.gc();
        longs = new long[longs.length+1_000_000];
        System.out.println("allocated new long array, size: " + longs.length);
      } else if ("q".equals(s)) {
        JavaMemory.stop = true;
      } else {
        //ignore ?
        System.out.println("press 'n' or 'q'");
      }
    }
  }
}