正文
Thread之四：java线程返回结果的方法
提示：扫一扫查出行【扫一扫了解最新限行尾号】
复制提示
两种方式：一种继承Thread类实现；一种通过实现Callable接口。
第一种方法：
因为实现Thread类的run方法自身是没有返回值的，所以不能直接获得线程的执行结果，但是可以通过在run方法里把最后的结果传递给实例变量，然后通过getXX方法获取该实例变量的值。继承实现的代码：
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()); } }
结果：
sleep 3 second.
result:=world3
结果2：
sleep 2 second.
result:=world2
第二种方法：
继承Callable接口后需要实现call方法，而call方法默认是可以有返回值的，所以可以直接返回想返回的内容。接口的实现代码：
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;
}
}
调用类：
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);
} }
结果：
sleep 5 second.
sleep 3 second.
result:=hello3,world5,
更多介绍见《Runnable、Callable、Future和FutureTask用法》
