倒计时代码

xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:id="@+id/ll_xsqg"
    android:paddingTop="8dp"
    android:paddingBottom="8dp"
    android:paddingLeft="16dp"
    android:orientation="horizontal"
    tools:context="com.example.daojishi.MainActivity">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textStyle="bold"
            android:textSize="14sp" />

        <TextView
            android:id="@+id/tv_hour"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:paddingTop="3dp"
            android:paddingBottom="3dp"
            android:paddingLeft="5dp"
            android:paddingRight="5dp"
            android:background="#000000"
            android:textColor="@android:color/white"
            android:textSize="12sp"
            android:text="02"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:textStyle="bold"
            android:textColor="@android:color/black"
            android:text=":"/>
        <TextView
            android:background="#000000"
            android:id="@+id/tv_minute"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:paddingTop="3dp"
            android:paddingBottom="3dp"
            android:paddingLeft="5dp"
            android:paddingRight="5dp"
            android:textColor="@android:color/white"
            android:textSize="12sp"
            android:text="15"/>
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:textStyle="bold"
            android:textColor="@android:color/black"
            android:text=":"/>
        <TextView
            android:background="#000000"
            android:id="@+id/tv_second"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:paddingTop="3dp"
            android:paddingBottom="3dp"
            android:paddingLeft="5dp"
            android:paddingRight="5dp"
            android:textColor="@android:color/white"
            android:textSize="12sp"
            android:text="36"/>


LinearLayout>

package com.example.daojishi;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;

import butterknife.BindView;
import butterknife.ButterKnife;

public class MainActivity extends AppCompatActivity {
    @BindView(R.id.tv_hour)
    TextView tvHour;
    @BindView(R.id.tv_minute)
    TextView tvMinute;
    @BindView(R.id.tv_second)
    TextView tvSecond;

    private long mHour = 02;
    private long mMin = 15;
    private long mSecond = 36;
    private boolean isRun = true;

    private Handler timeHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if (msg.what==1) {
                computeTime();
                if (mHour<10){
                    tvHour.setText("0"+mHour+"");
                }else {
                    tvHour.setText("0"+mHour+"");
                }
                if (mMin<10){
                    tvMinute.setText("0"+mMin+"");
                }else {
                    tvMinute.setText(mMin+"");
                }
                if (mSecond<10){
                    tvSecond.setText("0"+mSecond+"");
                }else {
                    tvSecond.setText(mSecond+"");
                }
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
        startRun();
    }


    /**
     * 开启倒计时
     */
    private void startRun() {
        new Thread(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                while (isRun) {
                    try {
                        Thread.sleep(1000); // sleep 1000ms
                        Message message = Message.obtain();
                        message.what = 1;
                        timeHandler.sendMessage(message);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }


    /**
     * 倒计时计算
     */
    private void computeTime() {
        mSecond--;
        if (mSecond < 0) {
            mMin--;
            mSecond = 59;
            if (mMin < 0) {
                mMin = 59;
                mHour--;
            }
        }
    }

}