Android实现简单计时器功能

本文实例为大家分享了Android实现简单计时器的具体代码，供大家参考，具体内容如下

布局

在res/layout 下进行布局

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<LinearLayout
 android:orientation="vertical"
 android:layout_width="match_parent"
 android:layout_height="match_parent" tools:layout_editor_absoluteY="0dp"
 tools:layout_editor_absoluteX="0dp">
<TextView
 android:text="00:00:00"
 android:textSize="60sp"
 android:gravity="center"
 android:layout_width="match_parent"
 android:layout_height="wrap_content" android:id="@+id/timeView"/>
<Button
 android:text="start"
 android:onClick="onClickStart"
 android:layout_width="match_parent"
 android:layout_height="wrap_content" android:id="@+id/start"/>
<Button
 android:text="stop"
 android:onClick="onClickStop"
 android:layout_width="match_parent"
 android:layout_height="wrap_content" android:id="@+id/stop"/>
<Button
 android:text="reset"
 android:onClick="onClickReset"
 android:layout_width="match_parent"
 android:layout_height="wrap_content" android:id="@+id/reset"/>
</LinearLayout>

</android.support.constraint.ConstraintLayout>

MainActivity

package com.test;

import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;

import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

private int seconds = 0;
private boolean running = false; //计时状态
private boolean wasRunning = false; //保存running的状态

//app进入后台，暂停计时
@Override
protected void onStop() {
super.onStop();
wasRunning = running;
running = false;
}

//重新进入app，开始计时
@Override
protected void onStart() {
super.onStart();
if(wasRunning) running = true;
}

//失去焦点(如分屏)，暂停计时
@Override
protected void onPause() {
super.onPause();
wasRunning = running;
running = false;
}

//获得焦点,重新开始计时
@Override
protected void onResume() {
super.onResume();
if(wasRunning) running = true;
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//获取保存的状态
if(savedInstanceState!=null){
 seconds = savedInstanceState.getInt("seconds");
 running = savedInstanceState.getBoolean("running");
 wasRunning = savedInstanceState.getBoolean("wasRunning");
}
runTime();
}

/**
*保存状态
*/
@Override
public void onSaveInstanceState(Bundle saveInstanceState) {

super.onSaveInstanceState(saveInstanceState);
saveInstanceState.putInt("seconds",seconds);
saveInstanceState.putBoolean("running",running);
saveInstanceState.putBoolean("wasRunning",wasRunning);
}
/**
* 响应button的onClick事件
* 方法名和onClick的值一致
*/
public void onClickStart(View button){
running = true;
}
public void onClickStop(View button){
running = false;
}
public void onClickReset(View button){
running = false;
seconds = 0;
}

/**
* 注意 ui线程不能被堵塞，因此不能在ui线程中调用sleep方法
* 只允许ui线程更新界面，不能在后台线程更新界面
*
* ** 使用ui线程的Handler定时更新 **
* 将任务封装到 Runnable的run方法中 ，通过Handler的
* post(立即提交任务)或postDelayed(实现定时调度)方法提交到ui线程
*/
private void runTime(){
final Handler handler = new Handler();
handler.post(new Runnable() {
 @Override
 public void run() {
 final TextView textView = findViewById(R.id.timeView);
 int hour = seconds /3600％24;
 int minute = seconds％3600/60;
 String time = String.format("％02d:％02d:％02d",hour,minute,seconds％60);
 textView.setText(time);
 if(running) seconds++;
 handler.postDelayed(this,1000);
 }
 }
);

}
}

测试

完成

来源：https://blog.csdn.net/m0_46267375/article/details/108777169