Thread

[Sangita Mishra]

Can anybody explain the flow of this program?

class A1 extends Thread {
String[] sa;
public A1(String[] sa) {this.sa = sa;}
public void run() {
synchronized (sa) {
while (!sa[0].equals("Done")) {
try {sa.wait();} catch (InterruptedException ie) {}
}}
System.out.print(sa[1] + sa[2] + sa[3]);
}}
class B11 {
private static String[] sa = new String[]{"Not Done","X","Y","Z"};
public static void main (String[] args) {
Thread t1 = new A1(sa); t1.start();
synchronized (sa) {
sa[0] = "Done";
sa[1] = "A"; sa[2] = "B"; sa[3] = "C";
sa.notify();
}}}

Output: ABC

[marc weber]

Hint: Consider the line t1.start(); in the main method of B11. What does this do? Will the instance of A1 run? If so, what will it do? If not, what will happen?

Reformatted with code tags...

class A1 extends Thread {
  String[] sa;
  public A1(String[] sa) {
    this.sa = sa;
  }
  public void run() {
    synchronized (sa) {
      while (!sa[0].equals("Done")) {
        try {
          sa.wait();
        } catch (InterruptedException ie) {}
      }
    }
    System.out.print(sa[1] + sa[2] + sa[3]);
  }
}
 
class B11 {
  private static String[] sa = new String[]{"Not Done","X","Y","Z"};
  public static void main (String[] args) {
    Thread t1 = new A1(sa);
    t1.start();
    synchronized (sa) {
      sa[0] = "Done";
      sa[1] = "A";
      sa[2] = "B";
      sa[3] = "C";
      sa.notify();
    }
  }
}

[ June 20, 2005: Message edited by: marc weber ]