Android Studio之显示本地时间

 

•效果展示图

　　

•代码

package com.example.table;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.Button;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

import java.text.SimpleDateFormat;
import java.util.Date;

public class ShowTimeActivity extends AppCompatActivity {

    private  Thread thread;
    private Handler handler;  //异步消息处理器
    private TextView tvTime;
    private SimpleDateFormat sdf;
    private boolean runing;
    private TextView Tv1;
    private Button Btn1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_show_time);

        tvTime = findViewById(R.id.tv_1);
        sdf = new SimpleDateFormat("hh:mm:ss");
        tvTime.setText(sdf.format(new Date()));

        //创建消息处理器 接受子线程发送的消息  根据它做出处理，跟新主界面的值
        handler = new Handler(){
            @Override
            public void handleMessage(Message msg) {
                super.handleMessage(msg);
                if(msg.what == 1){
                    tvTime.setText(sdf.format(new Date()));
                }
            }
        };

        thread = new Thread(new Runnable() {
            @Override
            public void run() {
                while (true){
                    //让线程  发送消息
                    handler.sendEmptyMessage(1);
                    //让线程  睡眠500毫秒
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
        //启动线程
        thread.start();
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ShowTimeActivity"
    android:background="#0288D1">

    <TextView
        android:id="@+id/tv_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:textSize="30sp"/>

</RelativeLayout>