Java Thread Problem

I use a thread to call a function in a new thread.

Here is the code I use

 private Thread runner2;

public void start2(){
  runner2 = new Thread(this);
  runner2.setPriority(Thread.MAX_PRIORITY);
  runner2.start();
}

and in run of thread

 public void run(){

Thread thisThread = Thread.currentThread();

if (runner2==thisThread){

  runner2.setPriority(Thread.MAX_PRIORITY);

callfunction1();
..
..
..
..

start2();to start a new thread

// END THIS THREAD

 runner2=null;
  try{
  runner2.destroy();
   }catch (NullPointerException e){
    //System.out.println("Bad URL: "+page);
  }
  }

I use start2() to start a new runner2 thread.

But my Question is When I call the function to start a new thread Will
the Original thread runner2 stopped or a new thread runner2 will be
created?

I want that runner2 thread first stop and then start a new thread
runner2. How to destroy a thread and start it again.

Once I call runner2.destroy, will that thread stops? And in case I
start a new thread runner2 will the old thread destroy both old & new
threads as both use same variable runner2?