Chronometer 计时器的使用

import android.widget.Chronometer;

sdk中的源码：

实现了开始计数，重置，暂停，格式化字符串

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.example.android.apis.view;
// Need the following import to get access to the app resources, since this
// class is in a sub-package.
import com.example.android.apis.R;
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;
public class ChronometerDemo extends Activity {
    Chronometer mChronometer;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.chronometer);
        Button button;
        mChronometer = (Chronometer) findViewById(R.id.chronometer);
        // Watch for button clicks.
        button = (Button) findViewById(R.id.start);
        button.setOnClickListener(mStartListener);
        button = (Button) findViewById(R.id.stop);
        button.setOnClickListener(mStopListener);
        button = (Button) findViewById(R.id.reset);
        button.setOnClickListener(mResetListener);
        button = (Button) findViewById(R.id.set_format);
        button.setOnClickListener(mSetFormatListener);
        button = (Button) findViewById(R.id.clear_format);
        button.setOnClickListener(mClearFormatListener);
    }
    View.OnClickListener mStartListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.start();
        }
    };
    View.OnClickListener mStopListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.stop();
        }
    };
    View.OnClickListener mResetListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.setBase(SystemClock.elapsedRealtime());
        }
    };
    View.OnClickListener mSetFormatListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.setFormat("Formatted time (%s)");
        }
    };
    View.OnClickListener mClearFormatListener = new OnClickListener() {
        public void onClick(View v) {
            mChronometer.setFormat(null);
        }
    };
}