感谢极客学院的视频
布局文件:
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.timer.MainActivity" >
<EditText
android:id="@+id/inputtime"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
/>
<Button
android:id="@+id/settime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="set"
/>
<TextView
android:id="@+id/showtime"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<LinearLayout
android:orientation="horizontal"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
>
<Button
android:id="@+id/starttime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="start"
/>
<Button
android:id="@+id/endtime"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:text="end"
/>
</LinearLayout>
</LinearLayout>
下面是Java文件:
package com.example.timer;
import java.util.Timer;
import java.util.TimerTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.ActionBarActivity;
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 ActionBarActivity implements OnClickListener{
EditText inputtime;
Button settime,starttime,endtime;
TextView showtime;
private int i = 0 ;
Timer timer = null;
TimerTask task = null;
private void init(){
inputtime = (EditText)findViewById(R.id.inputtime);
settime = (Button)findViewById(R.id.settime);
starttime = (Button)findViewById(R.id.starttime);
endtime = (Button)findViewById(R.id.endtime);
showtime = (TextView)findViewById(R.id.showtime);
settime.setOnClickListener(this);
starttime.setOnClickListener(this);
endtime.setOnClickListener(this);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch(v.getId()){
case R.id.settime:
showtime.setText(inputtime.getText().toString());
i = Integer.parseInt(inputtime.getText().toString());
break;
case R.id.starttime:
startTime();
break;
case R.id.endtime:
endTime();
break;
}
}
private Handler mHandler = new Handler(){
public void handleMessage(Message msg){
showtime.setText(msg.arg1+"");
startTime();
}
};
public void startTime(){
timer = new Timer();
task = new TimerTask(){
@Override
public void run() {
// TODO Auto-generated method stub
i--;
Message message = mHandler.obtainMessage();
message.arg1 = i;
mHandler.sendMessage(message);
}
};
timer.schedule(task,1000);//第二个参数表示以1000毫秒计时
}
public void endTime(){
timer.cancel();
}
}
设置监听可以implements OnClickListener接口然后重写onClick(View v)方法,然后给组件widget.setOnClickListener(this);然后在onClick()方法里抓取v.getId()
TextView.setText(xxxx)里xxxx必须是字符串类型否则崩溃,可以用xxx.toString()也可以xxx+""自动转化
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