Thread之四：java線程返回結果的方法

兩種方式：一種繼承Thread類實現；一種通過實現Callable接口。

第一種方法：

因為實現Thread類的run方法自身是沒有返回值的，所以不能直接獲得線程的執行結果，但是可以通過在run方法里把最后的結果傳遞給實例變量，然后通過getXX方法獲取該實例變量的值。繼承實現的代碼：

package com.dxz.thread;

import java.util.Random;
import java.util.concurrent.TimeUnit;

class RunThread extends Thread {
    private String runLog = "";
    private String name;

    public RunThread(String name) {
        this.name = name;
    }

    public void run() {
        try {
            int time = new Random().nextInt(10);
            System.out.println("sleep "+ time +" second.");
            TimeUnit.SECONDS.sleep(time);
            this.runLog = this.name + time;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public String getRunLog() {
        return this.runLog;
    }
}
package com.dxz.thread;
public class RunThreadTest {

    public static void main(String[] args) throws InterruptedException {
        RunThread runT = new RunThread("world");
        runT.start();
        runT.join();
        System.out.println("result:="+runT.getRunLog());

    }

}

結果：

sleep 3 second.
result:=world3

結果2：

sleep 2 second.
result:=world2

第二種方法：

繼承Callable接口后需要實現call方法，而call方法默認是可以有返回值的，所以可以直接返回想返回的內容。接口的實現代碼：

package com.dxz.thread;

import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;

class CallThread implements Callable<String> {
    private String runLog = "";
    private String name;

    public CallThread(String name) {
        this.name = name;
    }
    @Override
    public String call() throws Exception {
        try {
            int time = new Random().nextInt(10);
            System.out.println("sleep " + time + " second.");
            TimeUnit.SECONDS.sleep(time);
            this.runLog = this.name + time;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return runLog;
    }
}

調用類：

package com.dxz.thread;

import java.util.ArrayList;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class CallThreadTest {

    public static void main(String[] args) throws ExecutionException {
        String result = "";
        ExecutorService exs = Executors.newCachedThreadPool();
        ArrayList<Future<String>> al = new ArrayList<Future<String>>();
        al.add(exs.submit(new CallThread("hello")));
        al.add(exs.submit(new CallThread("world")));
        for (Future<String> fs : al) {
            try {
                result += fs.get() + ",";
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("result:="+result);
    }

}

結果：

sleep 5 second.
sleep 3 second.
result:=hello3,world5,

 

 更多介紹見《 Runnable、Callable、Future和FutureTask用法》