java創建線程的幾種方式，了解一下

1.繼承Thread，重寫run()   

public class MyThread extends Thread{
    @Override
    public void run() { System.out.println("運行過程"); } }

2.實現Runnable，重run()

public class MyRunnable implements Runnable {
    @Override
    public void run() { System.out.println("運行過程"); } }

3.實現Callable，重寫call()

注意：Callable接口是一個參數化的類型，只有一個call方法，call返回類型是參數類型。

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("運行過程"); return null; } }

 

面試題：有線程A、B、C，A、B同時執行，A、B執行完畢之后，執行C

分析：考同步運行和異步運行，A、B異步，AB和C同步（AB阻塞，執行完成后才能執行C）

代碼：（實現Callable，利用FutureTask創建A、B線程，調用get()方法阻塞A、B線程，最后啟動線程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 { //線程A、B同時運行，線程C在A、B之后運行  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); } } } }