1. LazykingCallable

public interface LazykingCallable<V> {  
    V call();  
}

2. LazykingFutureTask

public class LazykingFutureTask<V> implements Runnable{  
    private final LazykingCallable<V> callable;  
    private boolean flag = false; // 标识子线程是否执行结束 
    private V result;  
  
    public LazykingFutureTask(LazykingCallable<V> callable) {  
        this.callable = callable;  
    }  
  
    @Override  
    public void run() {  
        result = callable.call();  
        flag = true;  
        synchronized (this) {  
            this.notify();  
        }  
    }  
  
    public V get() {  
        if (!flag) {  
            synchronized (this) {  
                try {  
                    this.wait();  
                } catch (InterruptedException e) {  
                    throw new RuntimeException(e);  
                }  
            }  
        }  
        return result;  
    }  
}

3. CallableImpl

对编写的Callable和FutureTask进行测试

public class CallableImpl implements LazykingCallable<Integer>{  
  
    @Override  
    public Integer call() {  
        System.out.println(Thread.currentThread().getName() + ">>自定义Callable接口正在运行<<");  
        try {  
            Thread.sleep(3000);  
        } catch (InterruptedException e) {  
            throw new RuntimeException(e);  
        }  
        return 0;  
    }  
  
    public static void main(String[] args) {  
        CallableImpl callable = new CallableImpl();  
        LazykingFutureTask<Integer> lazykingFutureTask = new LazykingFutureTask<>(callable);  
        new Thread(lazykingFutureTask).start();  
        Integer result = lazykingFutureTask.get();  
        System.out.println(Thread.currentThread().getName() + ">>获取到结果：" + result + "<<");  
    }  
}