java - 在不使用 Runnable 和 Timer 类的情况下定期调用方法

Question

我想知道是否可以在不使用 Runnable 和 Timer 类的情况下定期调用方法。简而言之，如何在根本不创建新线程的情况下调用方法？谢谢。

Answer 1

I was wondering if it is possible to have a periodically call of a method, without using Runnable and Timer class

虽然您可以避免使用 Timer，但您将需要某些会定期触发的东西。

例如，您可以有一个确实有效的 Runnable，然后在任何 View(或 Handler) 安排自己在未来再次运行:

/***
  Copyright (c) 2012 CommonsWare, LLC
  Licensed under the Apache License, Version 2.0 (the "License"); you may not
  use this file except in compliance with the License. You may obtain a copy
  of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
  by applicable law or agreed to in writing, software distributed under the
  License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
  OF ANY KIND, either express or implied. See the License for the specific
  language governing permissions and limitations under the License.

  From _The Busy Coder's Guide to Android Development_
    http://commonsware.com/Android
 */

package com.commonsware.android.post;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

public class PostDelayedDemo extends Activity implements Runnable {
  private static final int PERIOD=5000;
  private View root=null;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    root=findViewById(android.R.id.content);
  }

  @Override
  public void onResume() {
    super.onResume();

    run();
  }

  @Override
  public void onPause() {
    root.removeCallbacks(this);

    super.onPause();
  }

  @Override
  public void run() {
    Toast.makeText(PostDelayedDemo.this, "Who-hoo!", Toast.LENGTH_SHORT)
         .show();
    root.postDelayed(this, PERIOD);
  }
}

(来自 this sample project)