Java Thread Example

class ThreadExample{
    static int sum,sum1,sum2,sum3;
    public static  void findsum() {

    Runnable readRun1 = new Runnable() {
      public void run() {
           try{
          Thread.sleep(1000);
          for(int i=1;i<=10;i++){
              sum1+=i;
          }
         //System.out.println(sum1);
       } catch(Exception ex) {
       }  
      }
    };
    Thread thread1 = new Thread(readRun1);
    thread1.start();

Runnable readRun2 = new Runnable() {
      public void run() {
          try{
          Thread.sleep(1000);
         for(int i=11;i<=20;i++){
              sum2+=i;
          }
          //System.out.println(sum2);
       } catch(Exception ex) {
       }  
      }
    };
    Thread thread2 = new Thread(readRun2);
    thread2.start();

Runnable readRun3 = new Runnable() {
      public void run() {
          try{
          Thread.sleep(1000);
         for(int i=21;i<=30;i++){
              sum3+=i;
          }
          //System.out.println(sum3);
       } catch(Exception ex) {
       }  
      }
    };
    Thread thread3 = new Thread(readRun3);
    thread3.start();

    Runnable main = new Runnable() {
      public void run() {
          try{
          Thread.sleep(1000);
         sum=sum1+sum2+sum3;
          System.out.println("Result is: "+sum);
       } catch(Exception ex) {
       }  
      }
    };
    Thread mainth = new Thread(main);
    mainth.start();
     }

    public static void main(String[] args) 
    { 
        ThreadExample.findsum();

    }
}