java必学必会之线程（2）

一、线程的优先级别

线程优先级别的使用范例：

package cn.galc.test;

public class TestThread6 {
 public static void main(String args[]) {
 MyThread4 t4 = new MyThread4();
 MyThread5 t5 = new MyThread5();
 Thread t1 = new Thread(t4);
 Thread t2 = new Thread(t5);
 t1.setPriority(Thread.NORM_PRIORITY + 3);// 使用setPriority()方法设置线程的优先级别，这里把t1线程的优先级别进行设置
 
 t1.start();
 t2.start();
 System.out.println("t1线程的优先级是：" + t1.getPriority());
 // 使用getPriority()方法取得线程的优先级别，打印出t1的优先级别为8
 }
}

class MyThread4 implements Runnable {
 public void run() {
 for (int i = 0; i <= 1000; i++) {
  System.out.println("T1：" + i);
 }
 }
}

class MyThread5 implements Runnable {
 public void run() {
 for (int i = 0; i <= 1000; i++) {
  System.out.println("===============T2：" + i);
 }
 }
}
　　run()方法一结束，线程也就结束了。

二、线程同步

synchronized关键字的使用范例：

package cn.galc.test;

public class TestSync implements Runnable {
 Timer timer = new Timer();

 public static void main(String args[]) {
 TestSync test = new TestSync();
 Thread t1 = new Thread(test);
 Thread t2 = new Thread(test);
 t1.setName("t1");// 设置t1线程的名字
 t2.setName("t2");// 设置t2线程的名字
 t1.start();
 t2.start();
 }

 public void run() {
 timer.add(Thread.currentThread().getName());
 }
}

class Timer {
 private static int num = 0;

 publicvoid add(String name) {// 在声明方法时加入synchronized时表示在执行这个方法的过程之中当前对象被锁定
 synchronized (this) {
  
  num++;
  try {
  Thread.sleep(1);
  } catch (InterruptedException e) {
  e.printStackTrace();
  }
  System.out.println(name + "：你是第" + num + "个使用timer的线程");
 }
 }
}

线程死锁的问题：

package cn.galc.test;


public class TestDeadLock implements Runnable {
 public int flag = 1;
 static Object o1 = new Object(), o2 = new Object();

 public void run() {
 System.out.println(Thread.currentThread().getName() + "的flag=" + flag);
 

 
 if (flag == 1) {
  synchronized (o1) {
  
  try {
   Thread.sleep(500);
  } catch (InterruptedException e) {
   e.printStackTrace();
  }
  synchronized (o2) {
   
   System.out.println("1");
  }
  }
 }
 

 
 if (flag == 0) {
  synchronized (o2) {
  
  try {
   Thread.sleep(500);
  } catch (InterruptedException e) {
   e.printStackTrace();
  }
  synchronized (o1) {
   
   System.out.println("0");
  }
  }
 }
 }

 public static void main(String args[]) {
 TestDeadLock td1 = new TestDeadLock();
 TestDeadLock td2 = new TestDeadLock();
 td1.flag = 1;
 td2.flag = 0;
 Thread t1 = new Thread(td1);
 Thread t2 = new Thread(td2);
 t1.setName("线程td1");
 t2.setName("线程td2");
 t1.start();
 t2.start();
 }
}

　　解决线程死锁的问题最好只锁定一个对象，不要同时锁定两个对象

生产者消费者问题：

package cn.galc.test;



public class ProducerConsumer {
 public static void main(String args[]){
  SyncStack stack = new SyncStack();
  Runnable p=new Producer(stack);
  Runnable c = new Consumer(stack);
  Thread p1 = new Thread(p);
  Thread c1 = new Thread(c);
  
  p1.start();
  c1.start();
 }
}


class SyncStack{ //支持多线程同步操作的堆栈的实现
 private int index = 0;
 private char []data = new char[6]; 
 public synchronized void push(char c){
 if(index == data.length){
 try{
  this.wait();
 }catch(InterruptedException e){}
 }
 this.notify();
 data[index] = c;
 index++;
 }
 public synchronized char pop(){
 if(index ==0){
  try{
  this.wait();
  }catch(InterruptedException e){}
 }
 this.notify();
 index--;
 return data[index];
 }
}


class Producer implements Runnable{
 SyncStack stack; 
 public Producer(SyncStack s){
 stack = s;
 }
 public void run(){
 for(int i=0; i<20; i++){
  char c =(char)(Math.random()*26+'A');
  stack.push(c);
  System.out.println("produced："+c);
  try{     
  Thread.sleep((int)(Math.random()*1000)); 
  }catch(InterruptedException e){
  }
 }
 }
}


class Consumer implements Runnable{
 SyncStack stack; 
 public Consumer(SyncStack s){
 stack = s;
 }
 public void run(){
 for(int i=0;i<20;i++){
  char c = stack.pop();
  System.out.println("消费："+c);
  try{     
  Thread.sleep((int)(Math.random()*1000));
  }catch(InterruptedException e){
  }
 }
 }
}

以上就是关于java线程的全部内容介绍，大家可以结合第一篇《java必学必会之线程（1）》进行学习，希望可以帮助到大家。