Java 实现多线程的几种方式汇总

我们先来看段示例代码

import java.util.concurrent.callable;
import java.util.concurrent.futuretask;

public class main {

  public static void main(string[] args) {
    //方法一：继承thread
    int i = 0;
//    for(; i < 100; i++){
//      system.out.println(thread.currentthread().getname() + " " + i);
//      if (i == 5) {
//        threadextendsthread threadextendsthread = new threadextendsthread();
//        threadextendsthread.start();
//      }
//    }
    
    //方法二：实现runnable
//    for(i = 0; i < 100; i++){
//      system.out.println(thread.currentthread().getname() + " " + i);
//      if (i == 5) {
//        runnable runnable = new threadimplementsrunnable();
//        new thread(runnable).start();
//        new thread(runnable).start();
//      }
//    }

    //方法三：实现callable接口
    callable<integer> callable = new threadimplementscallable();
    futuretask<integer> futuretask = new futuretask<>(callable);
    for(i = 0; i < 100; i++){
      system.out.println(thread.currentthread().getname() + " " + i);
      if (i == 5) {
        new thread(futuretask).start();
        new thread(futuretask).start();
      }
    }
    try {
      system.out.println("futuretask ruturn: " + futuretask.get());
    } catch (exception e) {
      e.printstacktrace();
    }
  }

}

接下来我们来详细探讨下java 实现多线程的几种方式

方法一，继承自thread

public class threadextendsthread extends thread {
  private int i;
  @override
  public void run() {
    for(; i < 100; i++) {
      system.out.println(getname() + " " + i); 
    }
  }
}

run方法为线程执行体，threadextendsthread对象即为线程对象。

方法二，实现runnable接口

public class threadimplementsrunnable implements runnable {
  private int i;
  @override
  public void run() {
    for(; i < 100; i++){
      system.out.println(thread.currentthread().getname() + " " + i);
    }
  }
}

run方法为线程执行体，使用时new一个thread对象，runnable对象作为target传递给thread对象。且同一个runnable对象可作为多个thread的target，这些线程均共享runnable对象的实例变量。

方法三，实现callable接口

import java.util.concurrent.callable;

public class threadimplementscallable implements callable<integer> {
  private int i;
  
  @override
  public integer call() throws exception {
    for(; i < 100; i++){
      system.out.println(thread.currentthread().getname() + " " + i);
    }
    return i;
  }
}

callable接口类似于runnable接口，但比对方强大，线程执行体为call方法，该方法具有返回值和可抛出异常。使用时将callable对象包装为futuretask对象，通过泛型指定返回值类型。可稍候调用futuretask的get方法取回执行结果。