java - 如何修复错误 "Only the original thread that created a view hierarchy can touch its views."

Question

我想每秒刷新屏幕上的计时器。我收到此错误并且无法修复它。

我尝试使用处理程序和 runOnUiThreat 但没有成功。

 runOnUiThread(new Runnable() {
        @Override
        public void run() {
            final Timer txtRefresher = new Timer();

            txtRefresher.schedule(new TimerTask() {
                @Override
                public void run() {
                    timerConfirmation.setText(String.format("%d", timer));

                    if (timer == 0) {
                        txtRefresher.cancel();
                    }
                }
            }, 199, 60000);
        }
    });

我希望更改 View 和 UI 而不会出现任何错误，并且我希望每秒都更改它。

Answer 1

在 UI 中的某些 View 上使用 postDelayed()。此示例 Activity 每 5000 毫秒显示一次 Toast:

/***
  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.

  Covered in detail in the book _The Busy Coder's Guide to Android Development_
    https://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 onStart() {
    super.onStart();

    run();
  }

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

    super.onStop();
  }

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