Android中的Chronometer

这个例子演示的是点击按钮之后，计数增长，到20后自动停止

其中main.xml代码为：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Chronometer
        android:id="@+id/chronometer1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Chronometer" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start" />

</LinearLayout>

java代码为：

package android.demo;

import android.app.Activity;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Chronometer;
import android.widget.Chronometer.OnChronometerTickListener;

public class AndroidDemo5Activity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button start = (Button) findViewById(R.id.button1);
        final Chronometer ch = (Chronometer) findViewById(R.id.chronometer1);

        start.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                ch.setBase(SystemClock.elapsedRealtime());
                ch.start();
            }
        });
        ch.setOnChronometerTickListener(new OnChronometerTickListener() {

            @Override
            public void onChronometerTick(Chronometer arg0) {
                if (SystemClock.elapsedRealtime() - ch.getBase() > 20 * 1000) {
                    ch.stop();
                }

            }
        });
    }
}