datapanel.java

< ProJavaProgrammingSecondEdition> 书中例程源码

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

public class DataPanel extends JPanel {

  protected JTextField nameField;
  protected JTextField ageField;

  public DataPanel() {
    buildDisplay();
  }

  public void validateInput() throws InputValidationException {
    String name = nameField.getText();
    if (name.length() == 0) {
      throw new InputValidationException("No name was specified",
                                          nameField);
    }
    String age = ageField.getText();
    try {
      int value = Integer.parseInt(age);
      if (value <= 0) {
        throw new InputValidationException("Age value must be " +
                                           "a positive integer",
                                           ageField);
      }
    }
    catch (NumberFormatException e) {
      throw new InputValidationException("Age value is missing " +
                                         "or invalid", ageField);
    }
  }

  protected void buildDisplay() {
    setLayout(new GridLayout(2, 2, 10, 5));
    JLabel label = new JLabel("Name:");
    add(label);
    nameField = new JTextField(10);
    add(nameField);
    label = new JLabel("Age:");
    add(label);
    ageField = new JTextField(10);
    add(ageField);
  }

}