標題:
事件處理與傾聽者
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作者:
tonyh
時間:
2018-12-15 14:32
標題:
事件處理與傾聽者
本帖最後由 tonyh 於 2021-8-6 11:36 編輯
視窗作業系統都是採取圖形使用者介面,其程式執行流程是採用事件驅動(Event Driver)方式運作。例如程式開始執行後,等待著事件的發生,如移動滑鼠到按鈕上點按一下,就可能會執行特定方法。
Java對於事件處理方式是採用「委派事件模式」,如下圖所示:
Java將產生事件的物件稱為「事件來源」,而接收事件的物件稱為「事件傾聽者」,處理事件的方法稱為「事件處理方法」。
以本範例為例,事件來源有 tf1、btn1、btn2 三個物件,這三個物件必須分別與事件傾聽者連結在一起(即為來源物件註冊傾聽者),當事件產生時,會將來源物件以傳遞參數的方式交給事件處理方法運作。
事件處理的傾聽者介面 ActionListener 由 java.awt.event 套件所提供,使用時要先匯入。
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Ch82 implements ActionListener
{
private JFrame fm;
private JLabel lb1, lb2;
private JTextField tf1, tf2;
private JButton btn1, btn2;
Ch82()
{
lb1=new JLabel("1坪=3.3058平方公尺",JLabel.CENTER);
lb1.setBounds(0, 10, 215, 30);
lb2=new JLabel("輸入坪數:");
lb2.setBounds(10, 40, 60, 40);
tf1=new JTextField();
tf1.setBounds(70, 45, 134, 30);
tf1.addActionListener(this);
tf2=new JTextField();
tf2.setBounds(10, 85, 195, 40);
tf2.setEditable(false);
btn1=new JButton("確定");
btn1.setBounds(10, 135, 92, 25);
btn1.addActionListener(this);
btn2=new JButton("清除");
btn2.setBounds(112, 135, 92, 25);
btn2.addActionListener(this);
fm=new JFrame("土地面積計算");
fm.setBounds(100, 100, 220, 200);
fm.setVisible(true);
fm.setResizable(false);
fm.setLayout(null);
fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fm.add(lb1);
fm.add(lb2);
fm.add(tf1);
fm.add(tf2);
fm.add(btn1);
fm.add(btn2);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==tf1 || e.getSource()==btn1)
{
double area=Double.parseDouble(tf1.getText())*3.3058;
String areaStr=String.valueOf(area);
//String areaStr=Double.toString(area);
tf2.setText("面積為: "+areaStr+" 平方公尺");
}
if(e.getSource()==btn2)
{
tf1.setText("");
tf2.setText("");
}
}
public static void main(String[] args) {
Ch82 app=new Ch82();
}
}
複製代碼
作者:
黃宥鈞
時間:
2018-12-15 15:03
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Ch82 implements ActionListener
{
private JFrame fm;
private JLabel lb1, lb2;
private JTextField tf1, tf2;
private JButton btn1, btn2;
Ch82()
{
lb1=new JLabel("1坪=3.3058平方公尺",JLabel.CENTER);
lb1.setBounds(0, 10, 215, 30);
lb2=new JLabel("輸入坪數:");
lb2.setBounds(10, 40, 60, 40);
tf1=new JTextField();
tf1.setBounds(70, 45, 134, 30);
tf1.addActionListener(this);
tf2=new JTextField();
tf2.setBounds(10, 85, 195, 40);
tf2.setEditable(false);
btn1=new JButton("確定");
btn1.setBounds(10, 135, 92, 25);
btn1.addActionListener(this);
btn2=new JButton("清除");
btn2.setBounds(112, 135, 92, 25);
btn2.addActionListener(this);
fm=new JFrame("土地面積計算");
fm.setBounds(100, 100, 220, 200);
fm.setVisible(true);
fm.setResizable(false);
fm.setLayout(null);
fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fm.add(lb1);
fm.add(lb2);
fm.add(tf1);
fm.add(tf2);
fm.add(btn1);
fm.add(btn2);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==tf1 || e.getSource()==btn1)
{
double area=Double.parseDouble(tf1.getText())*3.3058;
String areaStr=String.valueOf(area);
//String areaStr=Double.toString(area);
tf2.setText("面積為: "+areaStr+" 平方公尺");
}
if(e.getSource()==btn2)
{
tf1.setText("");
tf2.setText("");
}
}
public static void main(String[] args) {
Ch82 app=new Ch82();
}
}
複製代碼
作者:
高睿辰
時間:
2018-12-15 15:15
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Ch75 implements ActionListener
{
private JFrame fm;
private JLabel lb1, lb2;
private JTextField tf1, tf2;
private JButton btn1, btn2;
Ch75()
{
lb1=new JLabel("1坪=3.3058平方公尺",JLabel.CENTER);
lb1.setBounds(0, 10, 215, 30);
lb2=new JLabel("輸入坪數:");
lb2.setBounds(10, 40, 60, 40);
tf1=new JTextField();
tf1.setBounds(70, 45, 134, 30);
tf1.addActionListener(this);
tf2=new JTextField();
tf2.setBounds(10, 85, 195, 40);
tf2.setEditable(false);
btn1=new JButton("確定");
btn1.setBounds(10, 135, 92, 25);
btn1.addActionListener(this);
btn2=new JButton("清除");
btn2.setBounds(112, 135, 92, 25);
btn2.addActionListener(this);
fm=new JFrame("土地面積計算");
fm.setBounds(100, 100, 220, 200);
fm.setVisible(true);
fm.setResizable(false);
fm.setLayout(null);
fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fm.add(lb1);
fm.add(lb2);
fm.add(tf1);
fm.add(tf2);
fm.add(btn1);
fm.add(btn2);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==tf1 || e.getSource()==btn1)
{
double area=Double.parseDouble(tf1.getText())*3.3058;
String areaStr=String.valueOf(area);
tf2.setText("面積為: "+areaStr+" 平方公尺");
}
if(e.getSource()==btn2)
{
tf1.setText("");
tf2.setText("");
}
}
public static void main(String[] args) {
Ch75 app=new Ch75();
}
}
複製代碼
作者:
蕭澧邦
時間:
2018-12-15 15:18
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
public class Ch82 implements ActionListener{
JLabel lb1,lb2;
JTextField tf1,tf2;
JButton btn1,btn2;
JFrame fm;
Ch82() {
lb1 = new JLabel("1坪=3.3058平方公尺",JLabel.CENTER);
lb1.setBounds(0, 10, 215, 30);
lb2 = new JLabel("輸入坪數:");
lb2.setBounds(10, 40, 60, 40);
tf1 = new JTextField();
tf1.setBounds(70, 45, 134, 30);
tf1.addActionListener(this);
tf2 = new JTextField();
tf2.setBounds(10, 85, 195, 40);
tf2.setEditable(false);
btn1 = new JButton("確定");
btn1.setBounds(10, 135, 92, 25);
btn1.addActionListener(this);
btn2 = new JButton("清除");
btn2.setBounds(112, 135, 92, 25);
btn2.addActionListener(this);
fm = new JFrame("土地面積計算");
fm.setBounds(100, 100, 220, 200);
fm.setVisible(true);
fm.setResizable(false);
fm.setLayout(null);
fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fm.add(lb1);
fm.add(lb2);
fm.add(tf1);
fm.add(tf2);
fm.add(btn1);
fm.add(btn2);
}
public static void main(String[] args) {
Ch82 app = new Ch82();
}
@Override
public void actionPerformed(ActionEvent e) {
if(e.getSource()==tf1 || e.getSource()==btn1)
{
double area=Double.parseDouble(tf1.getText())*3.3058;
tf2.setText("面積為: "+area+" 平方公尺");
}
if(e.getSource()==btn2)
{
tf1.setText("");
tf2.setText("");
}
}
}
複製代碼
作者:
蔡幸融
時間:
2018-12-15 15:21
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
public class Ch76 implements ActionListener
{
JFrame fm;
JTextField tf2, tf1;
JLabel lb1, lb2;
JButton btn1, btn2;
Ch76()
{
tf1=new JTextField();
tf1.setBounds(70, 45, 134, 30);
tf1.addActionListener(this);
tf2=new JTextField();
tf2.setBounds(10, 85, 195, 40);
tf2.setEditable(false);
tf2.addActionListener(this);
lb1=new JLabel("1坪=3.3058平方公尺",JLabel.CENTER);
lb1.setBounds(0, 10, 215, 30);
lb2=new JLabel("輸入坪數:");
lb2.setBounds(10, 40, 60, 40);
btn1=new JButton("確定");
btn1.setBounds(10, 135, 92, 25);
btn1.addActionListener(this);
btn2=new JButton("清除");
btn2.setBounds(112, 135, 92, 25);
btn2.addActionListener(this);
fm=new JFrame("單位換算");
fm.setBounds(100, 100, 220, 200);
fm.setVisible(true);
fm.setResizable(false);
fm.setLayout(null);
fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fm.add(lb1);
fm.add(lb2);
fm.add(tf1);
fm.add(tf2);
fm.add(btn1);
fm.add(btn2);
}
public static void main(String[] args)
{
Ch76 app=new Ch76();
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==btn2)
{
tf1.setText("");
tf2.setText("");
}
if(e.getSource()==btn1 || e.getSource()==tf1)
{
Double area=Double.parseDouble(tf1.getText())*3.3058;
tf2.setText("面積為: "+area+" 平方公尺");
}
}
}
複製代碼
作者:
譚暐霖
時間:
2018-12-15 15:32
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JTextField;
import javax.swing.JLabel;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Ch81 implements ActionListener
{
private JFrame fm;
private JButton btn1, btn2;
private JTextField tf1, tf2;
private JLabel lb1, lb2;
Ch81()
{
fm=new JFrame("...");
lb1=new JLabel("1 坪 = 3.3058 m2",JLabel.CENTER);
lb2=new JLabel("Enter 坪數: ");
btn1=new JButton("Enter");
btn2=new JButton("Clear");
tf1=new JTextField();
tf2=new JTextField();
tf1.setBounds(70, 45, 134, 30);
tf1.addActionListener(this);
tf2.setBounds(10, 85, 195, 40);
tf2.setEditable(false);
lb1.setBounds(0, 10, 215, 30);
lb2.setBounds(10, 40, 60, 40);
btn1.setBounds(10, 135, 92, 25);
btn1.addActionListener(this);
btn2.setBounds(112, 135, 92, 25);
btn2.addActionListener(this);
fm.setBounds(100, 100, 220, 200);
fm.setVisible(true);
fm.setResizable(false);
fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fm.setLayout(null);
fm.add(btn1);
fm.add(btn2);
fm.add(tf1);
fm.add(tf2);
fm.add(lb1);
fm.add(lb2);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==btn2)
{
tf1.setText("");
tf2.setText("");
}
if(e.getSource()==btn1 || e.getSource()==tf1)
{
double area=Double.parseDouble(tf1.getText())*3.3058;
String areaStr=String.valueOf(area);
tf2.setText("面積為: "+areaStr+" 平方公尺");
}
}
public static void main(String[] args) {
Ch81 app=new Ch81();
}
}
複製代碼
作者:
莊旻叡
時間:
2019-1-7 19:30
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class Ch82 implements ActionListener
{
private JFrame fm;
private JLabel lb1, lb2;
private JTextField tf1, tf2;
private JButton btn1, btn2;
Ch82()
{
lb1=new JLabel("1坪=3.3058平方公尺",JLabel.CENTER);
lb1.setBounds(0, 10, 215, 30);
lb2=new JLabel("輸入坪數:");
lb2.setBounds(10, 40, 60, 40);
tf1=new JTextField();
tf1.setBounds(70, 45, 134, 30);
tf1.addActionListener(this);
tf2=new JTextField();
tf2.setBounds(10, 85, 195, 40);
tf2.setEditable(false);
btn1=new JButton("確定");
btn1.setBounds(10, 135, 92, 25);
btn1.addActionListener(this);
btn2=new JButton("清除");
btn2.setBounds(112, 135, 92, 25);
btn2.addActionListener(this);
fm=new JFrame("土地面積計算");
fm.setBounds(100, 100, 220, 200);
fm.setVisible(true);
fm.setResizable(false);
fm.setLayout(null);
fm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fm.add(lb1);
fm.add(lb2);
fm.add(tf1);
fm.add(tf2);
fm.add(btn1);
fm.add(btn2);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==tf1 || e.getSource()==btn1)
{
double area=Double.parseDouble(tf1.getText())*3.3058;
String areaStr=String.valueOf(area);
//String areaStr=Double.toString(area);
tf2.setText("面積為: "+areaStr+" 平方公尺");
}
if(e.getSource()==btn2)
{
tf1.setText("");
tf2.setText("");
}
}
public static void main(String[] args) {
Ch82 app=new Ch82();
}
}
複製代碼
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