最最基础的Android倒计时应用

只精确到秒

activity_main.xml

<LinearLayout 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"
android:orientation="vertical"
tools:context="com.example.counttime.MainActivity" >

<EditText
android:id="@+id/inputtime"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="number"
android:maxLength="9"
>

<requestFocus />

</EditText>

<Button
android:id="@+id/gettime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="获取倒计时时间" />

<TextView
android:id="@+id/time"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="40sp"
android:textColor="#0000FF"
android:gravity="center"
/>

<Button
android:id="@+id/starttime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="开始计时" />

<Button
android:id="@+id/stoptime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="停止计时" />

</LinearLayout>
MainActivity.java
package com.example.counttime;

import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener{

private EditText inputet;

private Button getTime,startTime,stopTime;
private TextView time;
private int i = 0;

private Timer timer;
private TimerTask task = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}

private void initView(){
inputet = (EditText) findViewById(R.id.inputtime);
getTime = (Button) findViewById(R.id.gettime);
startTime = (Button) findViewById(R.id.starttime);
stopTime = (Button) findViewById(R.id.stoptime);
time = (TextView) findViewById(R.id.time);

getTime.setOnClickListener(this);
startTime.setOnClickListener(this);
stopTime.setOnClickListener(this);
}

@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.gettime:
if(inputet.getText().toString().length()>0){
stopTime();
time.setText(inputet.getText().toString());
i = Integer.parseInt(inputet.getText().toString());
}

break;

case R.id.starttime:
startTime();
break;

case R.id.stoptime:
stopTime();
break;
}
}

private Handler handler = new Handler(){
public void handleMessage(Message msg) {
if(time.length()>0){
time.setText(msg.arg1+"");
if(!time.getText().toString().equals("0")){
startTime();
}
}
};
};

public void startTime(){
timer = new Timer();
task = new TimerTask() {

@Override
public void run() {
i--;
Message message = handler.obtainMessage();
message.arg1 = i;
handler.sendMessage(message);
}
};
timer.schedule(task, 1000);
}

public void stopTime(){
if(timer == null){
timer = new Timer();
}
timer.cancel();
}
}