Java Basic(54)-Event Handler Program

import java.awt.FlowLayout;

import java.awt.event.ActionListener;

import java.awt.event.ActionEvent;

import javax.swing.JFrame; →導入你必須需要什麼

import javax.swing.JTextField;

import javax.swing.JPasswordField;

import javax.swing.JOptionPane;

public class tuna extends JFrame{

private JTextField item1;

private JTextField item2; →三個TextField和passwordField

private JTextField item3;

private JPasswordField passwordField;

public tuna(){

super("The title");

setLayout(new FlowLayout());

item1 = new JTextField(10); →設置項目（constructor）

add(item1);

item2 = new JTextField("enter text here");

add(item2);

item3 = new JTextField("uneditable");

item3.setEditable(false);

add(item3);

passwordField = new JPasswordField("mypass");

add(passwordField);

thehandler handler = new thehandler(); →創建新對象

item1.addActionListener(handler); →設置處理程序(handler)

item2.addActionListener(handler);

item3.addActionListener(handler);

passwordField.addActionListener(handler);

}

private class thehandler implements ActionListener{ →必須這樣寫

public void actionPerformed(ActionEvent event){

String string = "";

if(event.getSource()==item1)

string=String.format("field 1: %s", event.getActionCommand());

else if(event.getSource()==item2)

string=String.format("field 2: %s", event.getActionCommand());

else if(event.getSource()==item3)

string=String.format("field 3: %s", event.getActionCommand());

else if(event.getSource()==passwordField)

string=String.format("password field is: %s" , event.getActionCommand());

JOptionPane.showMessageDialog(null, string); →顯示文字在TextField

}

}

}

import javax.swing.JFrame;

class apples{

public static void main(String[] args){

tuna bucky = new tuna();

bucky.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

bucky.setSize(350, 100);

bucky.setVisible(true);

}

這是運行時的結果： 

}