java创建线程的几种方式，了解一下

1.继承Thread，重写run()   

public class MyThread extends Thread{
    @Override
    public void run() { System.out.println("运行过程"); } }

2.实现Runnable，重run()

public class MyRunnable implements Runnable {
    @Override
    public void run() { System.out.println("运行过程"); } }

3.实现Callable，重写call()

注意：Callable接口是一个参数化的类型，只有一个call方法，call返回类型是参数类型。

public interface Callable<V> {
    /**
     * Computes a result, or throws an exception if unable to do so.
     *
     * @return computed result
     * @throws Exception if unable to compute a result
     */ V call() throws Exception; }

import java.util.concurrent.Callable;

public class MyCallale implements Callable<Integer> { @Override public Integer call() throws Exception { System.out.println("运行过程"); return null; } }

 

面试题：有线程A、B、C，A、B同时执行，A、B执行完毕之后，执行C

分析：考同步运行和异步运行，A、B异步，AB和C同步（AB阻塞，执行完成后才能执行C）

代码：（实现Callable，利用FutureTask创建A、B线程，调用get()方法阻塞A、B线程，最后启动线程C）

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException; import java.util.concurrent.FutureTask; public class CallableTest { public static void main(String[] args) throws InterruptedException, ExecutionException { //线程A、B同时运行，线程C在A、B之后运行  Callable<A> a = new Callable<A>(){ @Override public A call() throws Exception { for(int i = 0; i < 10; i++){ System.out.print(" A" + i); } return new A(); } }; Callable<B> b = new Callable<B>(){ @Override public B call() throws Exception { for(int i = 0; i < 10; i++){ System.out.print(" B" + i); } return new B(); } }; FutureTask<A> taskA = new FutureTask<A>(a); FutureTask<B> taskB = new FutureTask<B>(b); new Thread(taskA).start(); new Thread(taskB).start(); if(taskA.get() != null && taskB.get() != null){ new Thread(new C()).start(); } } static class A{} static class B{} static class C extends Thread{ @Override public void run() { for(int i = 0; i < 10; i++){ System.out.print(" C" + i); } } } }