Question

我想在android中开发一个简单的秒表逻辑。

单击列表视图时，计时器应该启动，单击按钮时计时器应该停止。任何人都可以指导我。任何示例代码都会有很大的帮助

Answer 1

使用Stopwatch类（使用更高精度System.nanoTime()）

在Button Presses上添加Start（）事件和Stop（）事件。您需要更新UI，因此请使用线程/处理程序组合。

这应该让你开始。

编辑：添加了代码。（很棒的运动！:)）

使用Refresh_Rate配置用户界面更新的频率。

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.TextView;

public class Main extends Activity implements OnClickListener{

    final int MSG_START_TIMER = 0;
    final int MSG_STOP_TIMER = 1;
    final int MSG_UPDATE_TIMER = 2;

    Stopwatch timer = new Stopwatch();
    final int REFRESH_RATE = 100;

    Handler mHandler = new Handler()
    {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
            case MSG_START_TIMER:
                timer.start(); //start timer
                mHandler.sendEmptyMessage(MSG_UPDATE_TIMER);
                break;

            case MSG_UPDATE_TIMER:
                tvTextView.setText(""+ timer.getElapsedTime());
                mHandler.sendEmptyMessageDelayed(MSG_UPDATE_TIMER,REFRESH_RATE); //text view is updated every second, 
                break;                                  //though the timer is still running
            case MSG_STOP_TIMER:
                mHandler.removeMessages(MSG_UPDATE_TIMER); // no more updates.
                timer.stop();//stop timer
                tvTextView.setText(""+ timer.getElapsedTime());
                break;

            default:
                break;
            }
        }
    };

    TextView tvTextView;
    Button btnStart,btnStop;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        tvTextView = (TextView)findViewById(R.id.TextView01);

        btnStart = (Button)findViewById(R.id.Button01);
        btnStop= (Button)findViewById(R.id.Button02);
        btnStart.setOnClickListener(this);
        btnStop.setOnClickListener(this);

    }

    public void onClick(View v) {
        if(btnStart == v)
        {
            mHandler.sendEmptyMessage(MSG_START_TIMER);
        }else
        if(btnStop == v){
            mHandler.sendEmptyMessage(MSG_STOP_TIMER);
        }
    }
}

Answer 2

由于st0le使用Stopwatch类给出了一个很好的例子。我稍微修改了这个类，并添加了一些方法。

/*
Copyright (c) 2005, Corey Goldberg

StopWatch.java is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

Modified: Bilal Rabbani bilalrabbani1@live.com (Nov 2013)
*/

package bilalrabbani1.at.live.com;

public class Stopwatch {
private long startTime = 0;
private boolean running = false;
private long currentTime = 0;

public void start() {
    this.startTime = System.currentTimeMillis();
    this.running = true;
}

public void stop() {
    this.running = false;
}

public void pause() {
    this.running = false;
    currentTime = System.currentTimeMillis() - startTime;
}
public void resume() {
    this.running = true;
    this.startTime = System.currentTimeMillis() - currentTime;
}

//elaspsed time in milliseconds
public long getElapsedTimeMili() {
    long elapsed = 0;
    if (running) {
         elapsed =((System.currentTimeMillis() - startTime)/100) % 1000 ;
    }
    return elapsed;
}

//elaspsed time in seconds
public long getElapsedTimeSecs() {
    long elapsed = 0;
    if (running) {
        elapsed = ((System.currentTimeMillis() - startTime) / 1000) % 60;
    }
    return elapsed;
}

  //elaspsed time in minutes
public long getElapsedTimeMin() {
    long elapsed = 0;
    if (running) {
        elapsed = (((System.currentTimeMillis() - startTime) / 1000) / 60 ) % 60;
    }
    return elapsed;
}

//elaspsed time in hours
public long getElapsedTimeHour() {
    long elapsed = 0;
    if (running) {
        elapsed = ((((System.currentTimeMillis() - startTime) / 1000) / 60 ) / 60);
    }
    return elapsed;
}

public String toString() {
    return getElapsedTimeHour() + ":" + getElapsedTimeMin() + ":"
            + getElapsedTimeSecs() + "." + getElapsedTimeMili();
}
}

此致

Answer 3

您无需使用列表视图，而只需将文本视图用于计时器，将3个按钮用于停止启动和重置。使用这些，您可以相应地编写Java代码

Answer 4

很好的例子，以防万一有人想要这个布局文件（非常简单）。

<RelativeLayout 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: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=".MainActivity" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/hello_world" />

<EditText
    android:id="@+id/TextView01"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/textView1"
    android:layout_below="@+id/textView1"
    android:layout_marginLeft="18dp"
    android:layout_marginTop="49dp"
    android:ems="10" >

    <requestFocus />
</EditText>

<Button
    android:id="@+id/Button01"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/TextView01"
    android:layout_marginTop="42dp"
    android:layout_toRightOf="@+id/textView1"
    android:text="Start" />

<Button
    android:id="@+id/Button02"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/Button01"
    android:layout_marginTop="14dp"
    android:layout_toRightOf="@+id/textView1"
    android:text="Stop" />

Compiled on Nexus-5

Answer 5

基于IntentService，没有非SDK依赖项和单个文件：

true

仅限低精度。我们可以通过在import android.app.Activity; import android.app.IntentService; import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.os.Bundle; import android.os.Handler; import android.support.v4.content.LocalBroadcastManager; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.LinearLayout; import android.widget.TextView; public class Main extends Activity { static final String BROADCAST_ACTION = "com.cirosantilli.android_cheat.intent_service_text_view.BROADCAST"; static final String EXTENDED_DATA_STATUS = "com.cirosantilli.android_cheat.intent_service_text_view.BROADCAST"; static final String TAG = "com.cirosantilli"; private int i = 0; @Override protected void onCreate(Bundle savedInstanceState) { Log.d(TAG, "onCreate"); super.onCreate(savedInstanceState); final LinearLayout linearLayout = new LinearLayout(this); Button button; final Intent intent = new Intent(Main.this, MyService.class); button = new Button(this); button.setText("start service"); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Log.d(TAG, "start button"); Main.this.startService(intent.putExtra(Main.EXTENDED_DATA_STATUS, Main.this.i)); } }); linearLayout.addView(button); button = new Button(this); button.setText("stop service"); button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Log.d(TAG, "stop button"); Main.this.stopService(intent); } }); linearLayout.addView(button); final TextView textView = new TextView(this); textView.setText(Integer.toString(i)); linearLayout.addView(textView); this.setContentView(linearLayout); LocalBroadcastManager.getInstance(this).registerReceiver( new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { Main.this.i = intent.getIntExtra(Main.EXTENDED_DATA_STATUS, 0); textView.setText(Integer.toString(Main.this.i)); } }, new IntentFilter(Main.BROADCAST_ACTION) ); } public static class MyService extends IntentService { private Handler mHandler; private int i = 1; private boolean done; public MyService() { super("MyService"); } @Override protected void onHandleIntent(Intent intent) { Log.d(TAG, "onHandleIntent"); this.i = intent.getIntExtra(Main.EXTENDED_DATA_STATUS, 0); this.done = false; while(!done) { Log.d(TAG, "while true"); try { Thread.sleep(1000); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } LocalBroadcastManager.getInstance(this).sendBroadcast( new Intent(Main.BROADCAST_ACTION) .putExtra(Main.EXTENDED_DATA_STATUS, MyService.this.i)); this.i++; } } @Override public void onDestroy() { Log.d(TAG, "onDestroy"); this.done = true; super.onDestroy(); } } }内使用System.currentTimeMillis而不是使用整数值来增加精度，并减少睡眠时间以减少延迟。

在Android 22上测试。标准构建样板here。

停止观察逻辑

5 个答案: