直接繼承Thread類,重寫run方法

package snippet;
public class test {
    public static void main(String[] args) {
        for (int i = 0; i < 5; i++) {
            new MyThread().start();
        }
    }
}
class MyThread extends Thread {
    @Override
    public void run() {
        for (int i = 1; i < 100; i++) {
            System.out.println(getName() + "--->" + i);
        }
    }
}

使用Runable接口+Thread

作為Thread 參數傳入(與上面沒有什么不同,只是為了減少設計的藕性)

package snippet;
public class test {
    public static void main(String[] args) {
        for (int i = 0; i < 5; i++) {
            new Thread(new MyRunnable()).start();
        }
    }
}
class MyRunnable implements Runnable {
    @Override
    public void run() {
        for (int i = 1; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + "--->" + i);
        }
    }
}

注意,當實現Runable接口并且覆寫Thread的run方法時,只會調用Thread的run方法.

使用Runable接口

使用Runable接口比較復雜,需要使用到線程池,但是它可以帶返回值。

package snippet;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
class MyCallable implements Callable<Integer> {
    
    private int    num1;
    private int    num2;
                
    public MyCallable(int num1, int num2) {
        try {
            this.num1 = num1;
            this.num2 = num2;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    @Override
    public Integer call() throws Exception {
        return num1 + num2;
    }
    
}
public class test {
    public static void main(String[] args) throws Exception {
        ExecutorService pool = Executors.newCachedThreadPool();
        /**
         * 創建一個線程池
         */
        List<Future<Integer>> results = new ArrayList<>();
        /**
         * Future<T>是泛型接口,其中泛型為返回數據類型
         */
        
        for (int i = 0; i < 5; i++) {
            Future<Integer> result = pool.submit(new MyCallable(i, i + 1));
            results.add(result);
        }
        
        for (int i = 0; i < results.size(); i++) {
            System.out.println(results.get(i).get());
        }
        /**
         * 使用get去獲取call方法返回的值,可設置超時. 因為有時候若等待時間太長,則造成體驗不好
         */
    }
}