4

任务 - 在一天中的指定时间打开和关闭灯泡。我需要知道如何根据下面给出的信息修复我的代码。我还需要知道我是否正确使用了计时器类，也就是说，我的代码设计是否正确？该代码可能有效，但它可能是糟糕的设计，稍后会导致问题。我不希望这种情况发生。

输出是（这不是我真正想要的输出：（）-

This is the main program
Current time is - xxx
Future time is - xxx+5sec
Future time is - xxx+10sec
Main program ends
Bulb B1 is OFF

所需的输出 -

This is the main program
Current time is - xxx
Future time is - xxx+5sec
Future time is - xxx+10sec
Bulb B1 is ON  //first on
Bulb B1 is OFF //then off
Main program ends//This should always be in the end.

如何修复下面的代码以获得我想要的？

Bulb班级

class Bulb {

private boolean state = false;//On or off
private String name;

Bulb(String name){

    this.name = name;

}

public void setState(boolean state){

    this.state = state;
    if(this.state == true){

        System.out.println("Bulb " + name + " is ON");

    }else{

        System.out.println("Bulb " + name + " is OFF");

    }

}


public boolean getState(){
    return this.state;

}


}

BulbJob类是一个TimerTask

import java.util.*;

class BulbJob extends TimerTask{

private Bulb bulbToHandle;
private boolean setBulbStateEqualTo;

BulbJob(Bulb toHandle){

    this.bulbToHandle = toHandle;

}


//NOTE: Must be called before run(), otherwise default value is used
public void setBulbStateEqualTo(boolean setBulbStateEqualTo){

    this.setBulbStateEqualTo = setBulbStateEqualTo;

}


//NOTE: call run() only before calling above method
public void run(){

    this.bulbToHandle.setState(setBulbStateEqualTo);//Set on or off

}

}

BulbSchedulerclass - 这安排了灯泡何时打开或关闭。

import java.util.*;

@SuppressWarnings( "deprecation" )
class BulbScheduler {

public static void main(String args[]) throws InterruptedException{

    System.out.println("This is the main program");

    Timer time = new Timer();
    Bulb b1 = new Bulb("B1");
    BulbJob bj = new BulbJob(b1);

    bj.setBulbStateEqualTo(true);//Task - Turn bulb on at time = afterCurrent

    Date current = new Date();//Get current time and execute job ten seconds after this time
    Date afterCurrent = (Date) current.clone();

    System.out.println("Current time is - " + current);

    int currentSecs = current.getSeconds();
    int offset = 5;//number of seconds

    afterCurrent.setSeconds(currentSecs + offset);
    System.out.println("Future time is - " + afterCurrent);

    time.schedule(bj, afterCurrent);//Schedule job "bj" at time = afterCurrent

    //Now turn the bulb off at new time = newest afterTime
    afterCurrent.setSeconds(currentSecs + 2 * offset);
    System.out.println("Future time is - " + afterCurrent);

    bj.setBulbStateEqualTo(false);//Task - Now turn the bulb off at time = afterCurrent

    System.out.println("Main program ends");

}

}
4

4 回答 4

2

本节：

time.schedule(bj, afterCurrent);//Schedule job "bj" at time = afterCurrent

//Now turn the bulb off at new time = newest afterTime
afterCurrent.setSeconds(currentSecs + 2 * offset);

只安排一项任务。如果您需要安排两次，请明确执行：

time.schedule(bj, afterCurrent);//Schedule job "bj" at time = afterCurrent

//Now turn the bulb off at new time = newest afterTime
afterCurrent.setSeconds(currentSecs + 2 * offset);
time.schedule(bj, afterCurrent);//Schedule job "bj" at time = afterCurrent

还。这一行：

bj.setBulbStateEqualTo(false);

在主线程中执行，因此它将在两个任务之前执行。您应该安排该语句在两个任务之间运行。

于 2013-03-11T08:20:12.193 回答
0

代码是固定的，但这个版本最终无法退出 main -

import java.util.*;

@SuppressWarnings( "deprecation" )
class BulbScheduler {

public static void main(String args[]) throws InterruptedException{

    System.out.println("This is the main program");

    Timer timeOn = new Timer();
    Timer timeOff = new Timer();
    Bulb b1 = new Bulb("B1");
    BulbJob bjOn = new BulbJob(b1);
    BulbJob bjOff = new BulbJob(b1);

    bjOn.setBulbStateEqualTo(true);//Task - Turn bulb on 
    bjOff.setBulbStateEqualTo(false);//Task - Then turn the bulb off later

    Date current = new Date();//Get current time and execute job ten seconds after this time
    Date afterCurrent = (Date) current.clone();

    System.out.println("Current time is - " + current);

    int currentSecs = current.getSeconds();
    int offset = 3;//number of seconds

    afterCurrent.setSeconds(currentSecs + offset);
    System.out.println("Future time is - " + afterCurrent);

    timeOn.schedule(bjOn, afterCurrent);//Schedule job "bj" at time = afterCurrent

    //Now turn the bulb off at new time = latest afterCurrent
    afterCurrent.setSeconds(currentSecs + 2 * offset);
    System.out.println("Future time is - " + afterCurrent);

    timeOff.schedule(bjOff, afterCurrent);

    System.out.println("Main program ends");

}

}
于 2013-03-11T09:02:01.027 回答
0

也可以使用定时器对象的 schedule(TimerTask task, long delay) 调度指定任务在指定延迟（毫秒）后执行。修改后的代码 - 

import java.util.*;

class BulbScheduler {

    private static java.text.SimpleDateFormat sdf1 = new java.text.SimpleDateFormat ("yy MM dd HH mm ss");

//helper    
static String formatDate(Date d){
        return sdf1.format(d);
    }

    public static void main(String args[]) throws InterruptedException{
        System.out.println("This is the main method");
        java.util.GregorianCalendar cal = new java.util.GregorianCalendar();

        Bulb b1 = new Bulb("bulb 1", false);
        Bulb b2 = new Bulb("bulb 2", false);

        System.out.println("Time now " + formatDate(cal.getTime()));

        Timer timer = new Timer("bulbs");
        BulbJob b1On = new BulbJob(b1, true);
        BulbJob b1Off = new BulbJob(b1, false);
        BulbJob b2On = new BulbJob(b2, true);
        BulbJob b2Off = new BulbJob(b2, false);
        timer.schedule(b1On, 3 * 1000);//after 3 seconds
        timer.schedule(b2On, 7 * 1000);//after 4 seconds
        timer.schedule(b1Off, 6 * 1000);//after 6 seconds; before b2 on

        b1On = new BulbJob(b1, true);
        timer.schedule(b1On, 9 * 1000);


        //if you want main to wait need to add code here to make it wait,
        // but even if does the JVM wont exit. Its just a method. The JVM exits when all non daemon threads are done
        // or System.exit is called

        System.out.println("This is the main method ending; but other threads might be running ...");
        //main thread JVM waits for all other non dameons to end

    }

}

改变灯泡工作

导入 java.util.*；

类 BulbJob 扩展 TimerTask{

private Bulb bulbToHandle;
private boolean bulbNewState;//dont start propert names with set

//why a seperate property when we need to set the new state everytime and cannot reuse jobs?
BulbJob(Bulb toHandle, boolean newState){
    this.bulbToHandle = toHandle;
    bulbNewState= newState;
}

public void run(){
    this.bulbToHandle.setState(bulbNewState);//Set on or off
}

}

类灯泡 ... public void setState(boolean state){ this.state = state; System.out.println("Bulb" + name +" is " + (state ? "on" : "off") + " at " + BulbScheduler.formatDate(new java.util.Date()));//if也可以

}

于 2013-03-11T10:25:26.293 回答
0

您没有正确设置时间。需要使用 GreogarianCalendar。

java.util.Date 被使用，但不能使用它的 setSeconds 阅读 Javadoc，它非常好，会有很大帮助。公共无效 setSeconds(int 秒)

已弃用。从 JDK 1.1 版开始，由 Calendar.set(Calendar.SECOND, int seconds) 取代。将此日期的秒数设置为指定值。修改此 Date 对象，使其表示指定秒内的时间点，其中年、月、日、小时和分钟与以前相同，按本地时区解释。

你需要使用 java.util.GregorianCalendar # add(Calendar.SECOND, howManySeconds)

然后使用 getDate() 获取 Date 对象并将其发送到 Timer。

在日期调用 setSecond 不会更改其他字段。请参阅 Calendar.add 和 roll 的 java 文档。http://docs.oracle.com/javase/1.5.0/docs/api/java/util/Calendar.html并查看类 inro 中的规则。

于 2013-03-11T09:15:32.363 回答