Runnable 和 Callable 有什么区别

Runnable 和 Callable 有什么区别？

主要区别

• Runnable 接口 run 方法无返回值；Callable 接口 call 方法有返回值，支持泛型
• Runnable 接口 run 方法只能抛出运行时异常，且无法捕获处理；Callable 接口 call 方法允许抛出异常，可以获取异常信息

 

测试代码如下

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

public class TestRunnableAndCallable {

	public static void main(String[] args) {
		testImplementsRunable();
		testImplementsCallable();
		testImplementsCallableWithException();
	}
	
	//测试实现Runnable接口的方式创建、启动线程
	public static void testImplementsRunable() {
		Thread t1 = new Thread(new CustomRunnable());
		t1.setName("CustomRunnable");
		t1.start();
	}
	
	//测试实现Callable接口的方式创建、启动线程
	public static void testImplementsCallable() {
		Callable callable = new CustomCallable();
		FutureTask futureTask = new FutureTask(callable);
		Thread t2 = new Thread(futureTask);
		t2.setName("CustomCallable");
		t2.start();
		try {
			System.out.println(futureTask.get());
		} catch (InterruptedException e) {
			e.printStackTrace();
		} catch (ExecutionException e) {
			e.printStackTrace();
		}
	}
	
	//测试实现Callable接口的方式创建、启动线程，抛出异常
	public static void testImplementsCallableWithException() {
		Callable callable = new CustomCallable2();
		FutureTask futureTask = new FutureTask(callable);
		Thread t3 = new Thread(futureTask);
		t3.setName("CustomCallableWithException");
		t3.start();
		try {
			System.out.println(futureTask.get());
		} catch (InterruptedException e) {
			e.printStackTrace();
		} catch (ExecutionException e) {
			e.printStackTrace();
		}
	}
	
}

//实现Runnable接口，重写run方法
class CustomRunnable implements Runnable {

	public void run() {
		System.out.println(Thread.currentThread().getName());
//		throw new RuntimeException("aaa");
	}
	
}

//实现Callable接口，重写call方法
class CustomCallable implements Callable {

	public String call() throws Exception {
		System.out.println(Thread.currentThread().getName());
		return "Callable Result";
	}
	
}

//实现Callable接口，重写call方法无法计算抛出异常
class CustomCallable2 implements Callable {

	public String call() throws Exception {
		System.out.println(Thread.currentThread().getName());
		throw new Exception("I can compute a result");
	}
	
}

 打印结果

CustomRunnable
CustomCallable
Callable Result
CustomCallableWithException
java.util.concurrent.ExecutionException: java.lang.Exception: I can compute a result
	at java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.util.concurrent.FutureTask.get(FutureTask.java:192)
	at constxiong.interview.TestRunnableAndCallable.testImplementsCallableWithException(TestRunnableAndCallable.java:46)
	at constxiong.interview.TestRunnableAndCallable.main(TestRunnableAndCallable.java:12)
Caused by: java.lang.Exception: I can compute a result
	at constxiong.interview.CustomCallable2.call(TestRunnableAndCallable.java:81)
	at constxiong.interview.CustomCallable2.call(TestRunnableAndCallable.java:1)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.lang.Thread.run(Thread.java:748)

 

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