Question

我创建了一个GUI界面，用户将nimber输入文本字段，然后将该数字作为参数添加到CurrentAccount的对象中。然后将该数字加到或减去随机值。我希望每5秒发生一次，在方程完成后取值，然后加上或减去一个值，直到用户告诉它停止。到目前为止，我已创建此代码以确定是否应添加减去的随机数，生成随机数，将其添加或减去帐户余额，然后将帐户余额打印到文本字段。

 //method generates a random number to determine if a value should be added or subtracted from the myBalance variable within theAccount classes and completes the equation
int month = 0;
private void simulate()
{
    try
    {
        if(month<12)
        { //Creates instance of Random to decide if the random number should be added or subtracted to the balance
            Random decider = new Random();
            for (int i = 0; i < 1; i++)
            {

                int ans = decider.nextInt(2)+1;

                //if the decider value == 1, subtract or "withdraw" random number from the balance
                if (ans == 1)

                {      
                    //creates instance of Random to create random number 
                Random bal = new Random();                
                    int withdrawAmount = bal.nextInt((500 - 100) + 1) + 100;

                    //sets account balance to the balance subtract the random number                    
                    theAccount.myBalance = theAccount.myBalance - withdrawAmount;   

                    //increments the month timer
                    month++;

                    //prints the new balance to the transaction text field
                   jTextArea2.setText("The new balance is " + theAccount.myBalance );
                } else
                { 
                    //if decider value == 2, add or "deposit" random number to the balance

                    //creates instance of Random to create random number 
                    Random bal = new Random();
                    int depositAmount = bal.nextInt((500 - 100) +1) + 100;

                    //sets account balance to the balance plus the random number
                    theAccount.myBalance= theAccount.myBalance + depositAmount;

                    //increments the month timer
                    month++;

                    //prints the new balance to the transaction text field
                    jTextArea2.setText("The new balance is " + theAccount.myBalance );
                }

                //if the account has a balance of -£200, generate an error and reset the balance to the user inputted value
                if (theAccount.myBalance < -200)
                {
                    jTextArea1.setText("Overdraft of £200 only");
                    theAccount.myBalance = value;
                }

                //if the account has a balance of 0, generate an error as the account must always have at least £1 before entering the overdraft
                if(theAccount.myBalance == 0)
                {
                    jTextArea1.setText("An account must always have £1");

                }

            }
        } 
    } catch (NullPointerException i)
    {
        jTextArea2.setText("Create an Account");
    }
}

我尝试过使用thread.sleep（5000）方法，但必须将它放在错误的位置，因为它会在创建按钮上停留5秒并自行打印出余额。对此事的任何帮助都会很棒。此外，我有一个方法来检测用户输入，显然是按钮上的动作监听器来调用它和这个方法。

[修改评论] 我也尝试使用计时器来循环代码，但我似乎无法指出正确的代码重复，因为它除了填充内存之外什么都不做。

 ActionListener timerListener = new ActionListener() 
        {
            public void actionPerformed(ActionEvent evt) 
            {
                ControlPanel.this.simulate();
            }
        };
       Timer theTimer = new Timer(5000,timerListener);

Answer 1

运行定期任务的另一种方法可能是使用ScheduledExecutorService

然后你的代码看起来像这样：

private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);

Runnable yourRunnable = new Runnable() {
    @Override
    public void run() {

        // Implement your Code here!

     }
};

然后运行你的任务：

int initialDelay = 0;
int delay = 5;
scheduler.scheduleWithFixedDelay(yourRunnable, initialDelay, delay, TimeUnit.SECONDS);

您的任务可能会被调用方法shutdown()

取消

scheduler.shutdown();

Answer 2

以下是java.util.Timer：

的示例

我们需要一个由Timer调用的任务：MyTimerTask

import java.util.Timer;
import java.util.TimerTask;

public class TimerTaskExample extends TimerTask {

    @Override
    public void run() {

        // Implement your Code here!
    }
}

然后我们必须安排一个Timer来执行这个任务：

Timer timer = new Timer();
timer.scheduleAtFixedRate(new MyTimerTask(), 0, 10 * 1000);

第一个参数是要执行的任务。

第二个参数表示第一次执行前的延迟。

第三个参数是以毫秒为单位的句点。（这里：每10秒执行一次！）

请注意，如果您想使用此机制在GUI中执行操作，则需要使用SwingUtilities.invokeLater()

编辑后的补充：

要使用javax.swing.Timer，您必须致电start()以使计时器运行。

每x秒执行一次代码

2 个答案: