Alguém pode me ajudar com threads?

package pointerJumping;

import java.util.Scanner;

public class Arvore {

	// Vetor que representa uma árvore.
	int vizinhos[];
	int num_vertices;

	// Construtor
	Arvore(int tamanho) {
		vizinhos = new int[tamanho];
		num_vertices = tamanho;
	}

	// Seleciona os vizinhos.
	public void setParent(){
		for (int i=0; i < vizinhos.length ;i++){
			System.out.println("Diga o vizinho do nó "+i+":");
			Scanner teclado = new Scanner(System.in);
			vizinhos[i]= teclado.nextInt();
		}
	}

	// Imprime a raiz de um dado nó.
	public void imprime(int no){
		System.out.println("Nó "+no+ " possui raiz "+vizinhos[no]);
	}

}

package pointerJumping;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;


class Pointer_Jumping implements Runnable {

	private String threadName;
	private Arvore arv;
	private int indice;
	private Lock pointerLock = new ReentrantLock();//ReentrantLock emplementa a inteface Lock.

	public Pointer_Jumping(String name, Arvore arvore, int ind){
		threadName = name;
		arv = arvore;
		indice = ind;
	}

	public void run() {

		System.out.println(threadName + "Trabalhando!!!");
		pointerLock.lock();
		try
		{
			while (arv.vizinhos[indice] != arv.vizinhos[arv.vizinhos[indice]])
			{
				//System.out.println(threadName + " Passou pelo while!!!");
				arv.vizinhos[indice]= arv.vizinhos[arv.vizinhos[indice]];
				//System.out.println(threadName + " Passou pela atribuicao!!!");

			}
			arv.imprime(indice);
		}
		finally
		{
			System.out.println(threadName + "Acabou!!!");
			pointerLock.unlock();
		}
	}
}

package pointerJumping;


public class Tester {


	public static void main(String[] args) throws InterruptedException {

		//Criação da árvore para teste.
		Arvore arv = new Arvore(5);
		arv.setParent();


		// Criação de objetos da classe Pointer_Jumping.
		Pointer_Jumping pj1 = new Pointer_Jumping("thread 1",arv,0);
		Pointer_Jumping pj2 = new Pointer_Jumping("thread 2",arv,1);
		Pointer_Jumping pj3 = new Pointer_Jumping("thread 3",arv,2);
		Pointer_Jumping pj4 = new Pointer_Jumping("thread 4",arv,3);
		Pointer_Jumping pj5 = new Pointer_Jumping("thread 5",arv,4);

		// Criação das Threads a partir de um objeto da classe Pointer_Jumping
		Thread threadComRunnable1 = new Thread(pj1);
		Thread threadComRunnable2 = new Thread(pj2);
		Thread threadComRunnable3 = new Thread(pj3);
		Thread threadComRunnable4 = new Thread(pj4);
		Thread threadComRunnable5 = new Thread(pj5);


		// Startando as Threads.
		threadComRunnable1.start();
		threadComRunnable2.start();
		threadComRunnable3.start();
		threadComRunnable4.start();
		threadComRunnable5.start();

	}
}