JavaFX - 等待任务完成

Question

我有一个 JavaFX 应用程序，它实例化了几个 Task 对象。

目前，我的实现（见下文）调用行为 runFactory() 在 Task 对象下执行计算。与此同时，nextFunction() 被调用。有没有办法让 nextFunction() “等待”直到前一个任务完成？

我了解 thread.join() 会一直等到正在运行的线程完成，但是对于 GUI，由于事件调度线程的原因，存在额外的复杂层。 事实上，将 thread.join() 添加到下面代码段的末尾只会停止 UI 交互。

如果有任何建议如何使 nextFunction 等到其先前的功能 runFactory 完成，我将非常感激。

谢谢，

// High-level class to run the Knuth-Morris-Pratt algorithm.
public class AlignmentFactory {
    public void perform() {
        KnuthMorrisPrattFactory factory = new KnuthMorrisPrattFactory();
        factory.runFactory();   // nextFunction invoked w/out runFactory finishing.
        // Code to run once runFactory() is complete.
        nextFunction()   // also invokes a Task.
        ...
    }
}

// Implementation of Knuth-Morris-Pratt given a list of words and a sub-string.
public class KnuthMorrisPratt {
   public void runFactory() throws InterruptedException {
       Thread thread = null;
       Task<Void> task = new Task<Void>() {

           @Override public Void call() throws InterruptedException {
           for (InputSequence seq: getSequences) {
                KnuthMorrisPratt kmp = new KnuthMorrisPratt(seq, substring);
                kmp.align();

            }
            return null; 
        }
    };
    thread = new Thread(task);
    thread.setDaemon(true);
    thread.start();
}

Answer 1

使用任务时，您需要使用setOnSucceeded 和可能的setOnFailed 在程序中创建逻辑流，我建议您也让runFactory() 返回任务而不是运行它：

// Implementation of Knuth-Morris-Pratt given a list of words and a sub-string.
public class KnuthMorrisPratt {
   public Task<Void> runFactory() throws InterruptedException {
       return new Task<Void>() {

       @Override public Void call() throws InterruptedException {
       for (InputSequence seq: getSequences) {
        KnuthMorrisPratt kmp = new KnuthMorrisPratt(seq, substring);
        kmp.align();

        }
        return null; 
    }
    };
}

// High-level class to run the Knuth-Morris-Pratt algorithm.
public class AlignmentFactory {
    public void perform() {
    KnuthMorrisPrattFactory factory = new KnuthMorrisPrattFactory();
    Task<Void> runFactoryTask = factory.runFactory();
    runFactoryTask.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
        @Override
        public void handle(WorkerStateEvent t)
        {
            // Code to run once runFactory() is completed **successfully**
            nextFunction()   // also invokes a Task.
        }
    });

    runFactoryTask.setOnFailed(new EventHandler<WorkerStateEvent>() {
        @Override
        public void handle(WorkerStateEvent t)
        {
            // Code to run once runFactory() **fails**
        }
    });
    new Thread(runFactoryTask).start();
    }
}