如何在Android中显示和隐藏进度条？

<ProgressBar
    android:id="@+id/progressBar"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:visibility="invisible" />

ProgressBar progressBar = findViewById(R.id.progressBar);

// 显示进度条
progressBar.setVisibility(View.VISIBLE);

// 隐藏进度条
progressBar.setVisibility(View.INVISIBLE);

private class MyTask extends AsyncTask<Void, Void, Void> {
    private ProgressBar progressBar;

    public MyTask(ProgressBar progressBar) {
        this.progressBar = progressBar;
    }

    @Override
    protected void onPreExecute() {
        // 在任务开始前显示进度条
        progressBar.setVisibility(View.VISIBLE);
    }

    @Override
    protected Void doInBackground(Void... params) {
        // 后台任务逻辑
        // ...
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        // 在任务结束后隐藏进度条
        progressBar.setVisibility(View.INVISIBLE);
    }
}