java - 我的程序需要帮助

Question

我在 Java 中有这个程序 import java.util.*;

public class Euclid {

    private static final String EXCEPTION_MSG = 
        "Invalid value (%d); only positive integers are allowed. ";

    public static int getGcd( int a, int b)
        {
            if (a < 0)
               {
                   throw new IllegalArgumentException(String.format(EXCEPTION_MSG, a));
               }
                else 
                    if (b < 0) 
                    { 
                        throw new IllegalArgumentException(String.format(EXCEPTION_MSG, b));
                    }

            while (b != 0)
            {


                if (a > b) 
                    {
                    a = a - b;
                           }      
                 else 
                   {
                      b   = b - a;
                    }    
            }
              return a;
        }
    }

<小时/>

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;

public class EuclidGui
{ 
  private static final String PROMPT_A = "#1";
  private static final String PROMPT_B = "#2";
  private static final String BUTTON_TEXT = "Get GCD >>";
  private static final String EXCEPTION_TITLE = "Input Exception";
  private static final String INSTRUCTIONS =    "Type to integer and press 'Get GCD'";
  private static final String DIALOG_TITLE = "Euclid's Algorithm";
  private static final int FIELD_WIDTH = 6;

public static void main (String[] args)
{
final JTextField valueA = new JTextField (FIELD_WIDTH);
final JTextField valueB = new JTextField (FIELD_WIDTH);
final JTextField valueGcd = new JTextField (FIELD_WIDTH);
JLabel labelA = new JLabel(PROMPT_A);
JLabel labelB = new JLabel(PROMPT_B);
JButton computeButton = new JButton(BUTTON_TEXT);
Object[] options = new Object[] {labelA, valueA, labelB, valueB, computeButton, valueGcd};
valueGcd.setEditable (false);
computeButton.addActionListener(new ActionListener() 
{
    public void actionPerformed(ActionEvent evt)
    { try
        { 
           int a = Integer.parseInt(valueA.getText());
           int b = Integer.parseInt(valueB.getText());
           int gcd = Euclid.getGcd(a , b);

           valueGcd.setText(Integer.toString(gcd));
         } 
         catch (Exception e)
         {
             JOptionPane.showMessageDialog(null, e.getMessage(), EXCEPTION_TITLE, JOptionPane.ERROR_MESSAGE);

         }
        }
    });
    JOptionPane.showOptionDialog(null, INSTRUCTIONS, DIALOG_TITLE, JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE,
    null, options, null);
}      
}    

我想在上面添加计算时间代码，但我不知道如何添加，以及我使用的正确代码是什么。如果有人有想法，请帮助我。

Answer 1

System.currentTimeMillis()就可以了:

long start = System.currentTimeMillis();
// do stuff
long timeTaken = System.currentTimeMillis() - start;