classaverage.java

适合与JAVA初级程序员 适合JAVA初学者编程

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ClassAverage extends JFrame
{

     private JLabel gradeListJLabel;
     private JTextArea gradeListJTextArea;
     private JButton getGradesJButton;
     private JButton averageJButton;
     private JLabel classAverageJLabel;
     private JTextField classAverageJTextField;
     private int total = 0;

     public ClassAverage()
     {

         createUserInterface();
     }

     private void createUserInterface()
     {

         Container contentPane = getContentPane();
         contentPane.setLayout(null);

         gradeListJLabel = new JLabel();
         gradeListJLabel.setBounds(16,8,70,23);
         gradeListJLabel.setText("Grade list:");
         contentPane.add(gradeListJLabel);

         gradeListJTextArea = new JTextArea();
         gradeListJTextArea.setBounds(16,32,88,180);
         contentPane.add(gradeListJTextArea);

         getGradesJButton = new JButton();
         getGradesJButton.setBounds(128,50,100,26);
         getGradesJButton.setText("Get Grades");
         contentPane.add(getGradesJButton);
         getGradesJButton.addActionListener(
     
            new ActionListener()
            {

                public void actionPerformed(ActionEvent event)
                {
                   getGradesJButtonActionPerformed(event);
                }
             }
         
         );

         averageJButton = new JButton();
         averageJButton.setBounds(128,90,100,26);
         averageJButton.setText("Average");
         averageJButton.setEnabled(false);
         contentPane.add(averageJButton);
         averageJButton.addActionListener(

             new ActionListener()
             {

                 public void actionPerformed(ActionEvent event)
                 {

                    averageJButtonActionPerformed(event);
                 }
              }

         );

         classAverageJLabel = new JLabel();
         classAverageJLabel.setBounds(128,132,90,23);
         classAverageJLabel.setText("Class average:");
         contentPane.add(classAverageJLabel);

         classAverageJTextField = new JTextField();
         classAverageJTextField.setBounds(128,156,100,21);
         classAverageJTextField.setEditable(false);
         classAverageJTextField.setHorizontalAlignment(JTextField.CENTER);
         contentPane.add(classAverageJTextField);

         setTitle("Class Average");
         setSize(250,250);
         setVisible(true);

      }

      private void getGradesJButtonActionPerformed(ActionEvent event)
      {

         total = 0;
         int counter = 1;
         String input ;
         int grade;

         gradeListJTextArea.setText("");
         classAverageJTextField.setText("");

         do
         {

            input = JOptionPane.showInputDialog(null,"Enter Grade");
            grade = Integer.parseInt(input);
            gradeListJTextArea.append(grade + "\n");
            total += grade;
            counter++;
          }
          while(counter <= 10);
          averageJButton.setEnabled(true);
          averageJButton.requestFocusInWindow();
       }

       private void averageJButtonActionPerformed(ActionEvent event)
       {

          double average = (double)total / 10;
          classAverageJTextField.setText(String.valueOf(average));

        }

       public static void main(String[]args)
       {

           ClassAverage application = new ClassAverage();
           application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        }

}