Question

我是Android开发的新手。我正在尝试显示 ProgressDialog 。我看到很多教程说显示对话框必须使用线程。正如您所看到的，代码片段正在使用线程。

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        try {
            refreshFromFeed();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        setContentView(R.layout.activity_main);
    }

private void refreshFromFeed() throws InterruptedException {
        ProgressDialog dialog = ProgressDialog.show(this,"Loading","Wake up after some sleep");
        Thread th = new Thread(){
            public void run(){
                Log.d("TimeFrom", String.valueOf(System.currentTimeMillis()/1000));
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                Log.d("TimeTo", String.valueOf(System.currentTimeMillis()/1000));
            }
        };
        th.start();
        dialog.dismiss();
    }
protected void onRefresh(View view) throws InterruptedException {
        refreshFromFeed();
    }

日志显示花了5秒钟，然而，我在屏幕上看不到任何对话框，我可以在屏幕上做任何事情。甚至我在物理设备上使用。我使用过调试模式。没有例外。

onRefresh 是onClick在其上声明的xml事件。

Answer 1

我已经对您的代码进行了一些更改，请仔细阅读。

private void refreshFromFeed() throws InterruptedException {
    ProgressDialog dialog = ProgressDialog.show(this,"Loading","Wake up after some sleep");
    Thread th = new Thread(){
        public void run(){
            Log.d("TimeFrom", String.valueOf(System.currentTimeMillis()/1000));
            try {
                Thread.sleep(5000);
                dialog.dismiss();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            Log.d("TimeTo",String.valueOf(System.currentTimeMillis()/1000));
        }
    };
    th.start();

}

Answer 2

您在显示对话框后立即解雇对话框。也许你想移动你的“dialog.dismiss（）;”在线程内部。请记住，您需要关闭UI线程上的对话框，否则会导致您的应用崩溃：

private void refreshFromFeed() throws InterruptedException {
        final ProgressDialog dialog = ProgressDialog.show(this,"Loading","Wake up after some sleep");
        Thread th = new Thread(){
            public void run(){
                Log.d("TimeFrom", String.valueOf(System.currentTimeMillis()/1000));
                try {
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                Log.d("TimeTo", String.valueOf(System.currentTimeMillis()/1000));

                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        dialog.dismiss();
                    }
                });
            }
        };
        th.start();
    }

我看到许多用于显示对话框的教程必须使用线程。

你没有明确需要一个线程来显示ProgressDialog，这只是一个在5000毫秒后解除它的例子

Answer 3

 private void refreshFromFeed() throws InterruptedException {
        final ProgressDialog dialog = ProgressDialog.show(getActivity(),"Loading","Wake up after some sleep");
        Thread th = new Thread() {
            public void run() {
                Log.d("TimeFrom", String.valueOf(System.currentTimeMillis() / 1000));
                try {
                    Thread.sleep(5000);
                    dialog.dismiss(); // dismiss your dialog here
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                Log.d("TimeTo", String.valueOf(System.currentTimeMillis() / 1000));
            }
        };
        th.start();
    }

Answer 4

您仍然在UI线程中运行ProgressDialog。

ProgressDialog dialog = ProgressDialog.show(this,"Loading","Wake up after some sleep");

在此行之后创建的新主题，而不是在此行之前！

即使使用线程，ProgressDialog也不起作用

4 个答案: