TextView顯示系統時間(時鐘功能帶秒針變化

2020-04-11 11:59:44

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來源：轉載

供稿：網友

我們開啟一個線程，線程每隔一秒發送一次消息，我們在消息中更新TextView上顯示的時間就ok了。

首先我們在布局文件中放一個TextView用來顯示時間，如下所示：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="@android:color/white">
  <TextView
      android:id="@+id/mytime"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:gravity="center"
      android:textColor="@android:color/black"
      android:textSize="36sp"/>
</LinearLayout>

之后我們寫一個線程，線程里面無限循環，每隔一秒發送一個消息,其中由Handler來處理顯示的結果：

復制代碼代碼如下:

public class TimeThread extends Thread {
        @Override
        public void run () {
            do {
                try {
                    Thread.sleep(1000);
                    Message msg = new Message();
                    msg.what = msgKey1;
                    mHandler.sendMessage(msg);
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } while(true);
        }
    }

private Handler mHandler = new Handler() {
        @Override
        public void handleMessage (Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case msgKey1:
                    long sysTime = System.currentTimeMillis();
                    CharSequence sysTimeStr = DateFormat.format("hh:mm:ss", sysTime);
                    mTime.setText(sysTimeStr);
                    break;

                default:
                    break;
            }
        }
    };

之后我們可以在Activity的onCreate方法中開啟這個線程，這時我們可以看到一個數字時鐘了：

復制代碼代碼如下:

public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.time);
         mTime = (TextView) findViewById(R.id.mytime);
         new TimeThread().start();
     }

整個Activity的代碼：

復制代碼代碼如下:

package com.fermax.test;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.format.DateFormat;
import android.widget.TextView;

public class TestActivity extends Activity {

    private static final int msgKey1 = 1;
    private TextView mTime;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.time);
        mTime = (TextView) findViewById(R.id.mytime);
        new TimeThread().start();
    }

    public class TimeThread extends Thread {
        @Override
        public void run () {
            do {
                try {
                    Thread.sleep(1000);
                    Message msg = new Message();
                    msg.what = msgKey1;
                    mHandler.sendMessage(msg);
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } while(true);
        }
    }

    private Handler mHandler = new Handler() {
        @Override
        public void handleMessage (Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case msgKey1:
                    long sysTime = System.currentTimeMillis();
                    CharSequence sysTimeStr = DateFormat.format("hh:mm:ss", sysTime);
                    mTime.setText(sysTimeStr);
                    break;

                default:
                    break;
            }
        }
    };
}