Android 线程+自制简易定时器

忘是亡心i 2022-07-17 01:08 151阅读 0赞

**实现效果：利用通信机制hander的用法，设计一个定时器，点击开始计时按钮时，**

**中间数字从100开始倒计时，到0结束。**

**布局：**

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.example.administrator.youraisemeup.TimeActivity">
       <TextView
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:id="@+id/tv"
        android:textSize="50sp"
        android:gravity="center"
        />
        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="点击计时"
            android:id="@+id/button"
            android:layout_centerVertical="true"
            android:layout_centerHorizontal="true" />
    </RelativeLayout>

**代码：**

package com.example.administrator.jreduch09;
    
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.support.v7.app.AppCompatActivity;
    import android.view.View;
    import android.widget.Button;
    import android.widget.TextView;
    
    public class TimeNActivity extends AppCompatActivity {
        private TextView show;
        private Button button;
        private Handler handler=new Handler(){
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                if(msg.what==1){
                    show.setText(msg.what + "");
                }else{
                    show.setText("倒计时结束");
                }
            }
        };
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_time);
            show= (TextView) findViewById(R.id.show);
            button= (Button) findViewById(R.id.button);
            show.setText("100");
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    new Thread(new MyJob()).start();
                }
            });
        }
        public class MyJob implements Runnable{
    
            @Override
            public void run() {
                int i=100;
                while (i>=0){
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    i--;
                    Message message=new Message();
                    message.what=i;
                    handler.sendMessage(message);
                }
            }
        }
    }

**完成效果：**

**![Center][]**

**![Center 1][]**

![Center 2][]

[Center]: /images/20220717/87db69d2336b484b8079523fe222892c.png
[Center 1]: /images/20220717/9bacf7b7255047ee985b4315c7aa98fc.png
[Center 2]: /images/20220717/d4ea8f6108684ecbaf6d79bd6eb8569e.png