Question

我正在尝试创建一个连接到站点的小型服务来进行操作，并在此过程中更新当前的textview。在进入for循环之前，没有任何问题，因为该活动停止了，直到它没有结束时它才变成白色。

我想逐步更新文本。

我创建了一个异步任务，但它给我错误' failed to load window。

下面是我的代码，我声明我放了所有权限。

public class GameTask extends AsyncTask<String, Integer, Long> {

private ProgressBar progressBar;
private TextView text;

public GameTask(ProgressBar progressBar, TextView text) {
    this.progressBar = progressBar;
    this.text = text;
}

@Override
protected Long doInBackground(String... strings) {
    startGameThread(progressBar, text);
    return null;
}


private void startGameThread (final ProgressBar progressBar, final TextView text) {
    final Handler mHandler = new Handler();
    final Runnable mRunnable = new Runnable() {
                @Override
                public void run() {
                    try {
                        progressBar.setProgress(0);
                        text.setText("Thread Iniziato...");
                        for (int i = 0; i <= 1000; i++) {
                            if (i == 0 || i % 10 == 0) {
                                text.setText("NUMBER " + i);
                            }
                        }
                        progressBar.setProgress(100);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                }
            };
    new Thread(mRunnable).start();
}
}

Answer 1

尝试将此方法导入AsyncTask

    @Override
    protected void onProgressUpdate(Integer... values) {
        super.onProgressUpdate(values);

        try {
            progressBar.setProgress(0);
            text.setText("Thread Iniziato...");
            for (int i = 0; i <= 1000; i++) {
                if (i == 0 || i % 10 == 0) {
                    text.setText("NUMBER " + i);
                }
            }
            progressBar.setProgress(100);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Answer 2

由于此进程正在AsyncTask中运行，因此您需要使用runOnUiThread方法来更新TextView。用户界面只能在MainThread上更新。

     private void startGameThread () {
//        final Handler mHandler = new Handler();

                final Runnable mRunnable = new Runnable() {
                    @Override
                    public void run() {
                        for (int i = 0; i <= 1000; i++) {
                            if (i == 0 || i % 10 == 0) {
                                final int finalI = i;
                                activity.runOnUiThread(new Runnable() {
                                    @Override
                                    public void run() {

                                        textView.setText(String.valueOf(finalI));
                                    }
                                });

                                try {
                                    Thread.sleep(2000);
                                } catch (InterruptedException e) {
                                    e.printStackTrace();
                                }
                            }
                        }

                    }
                };
                new Thread(mRunnable).start();



    }

Answer 3

您可以充分利用AsyncTask来在没有Handler的情况下在后台和UI线程中执行任务：

public class GameTask extends AsyncTask<String, Integer, Long> {

    private ProgressBar progressBar;
    private TextView text;

    public GameTask(ProgressBar progressBar, TextView text) {
        this.progressBar = progressBar;
        this.text = text;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // UI thread
        text.setText("Thread Iniziato...");
    }

    @Override
    protected Long doInBackground(String... strings) {
        // Non-UI thread
        for (int i = 0; i <= 1000; i++) {
            if (i == 0 || i % 10 == 0) {
                publishProgress(i/100, i);
            } else {
                publishProgress(i/100);
            }
            try {
                Thread.sleep(100); // Backpressure if needed for your sample
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        super.onProgressUpdate(values);
        // UI thread
        progressBar.setProgress(values[0]);
        if (values.length > 1) {
            text.setText("NUMBER " + values[1]);
        }
    }
}

如何动态更新TextView

3 个答案: