理解java的問題ActionListener - 執行（ActionEvent e）

Question

我必須爲Fibonacci程序編寫代碼，該程序構建一個帶有兩個文本框和一個按鈕的GUI。用戶在文本框1中輸入一個數字，然後單擊該按鈕，然後放置該數字的斐波納契數。我在理解java的actionPerformed部分時遇到問題，並希望得到任何幫助。這是我的代碼：有3個文件。

Fibonacci.java

public class Fibonacci{ 
    int Fib (int n){ 
     int in1=1,in2=1; 
     int sum=0;//initial value 
     int index=1; 
     while (index<n){ 
     sum=in1+in2;//sum=the sum of 2 values; 
     in1=in2;//in1 gets in2 
     in2=sum;//in2 gets sum 
     index++; //increment index 
     } 
    return sum; 
    } 
} 

FibonacciJPanel.java

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


public class FibonacciJPanel extends JPanel implements ActionListener 
{ private JTextField inField = new JTextField(15); //GUI components 
    private JTextField resultField = new JTextField(15); 
    private JLabel prompt1 = new JLabel("Input Fibonacci>>"); 
    private JLabel prompt2 = new JLabel("Conversion Result:"); 
    private JButton FibonacciButton = new JButton("Fibonacci of the input"); 
    private JPanel panelN = new JPanel();  //Panels 
    private JPanel panelC = new JPanel(); 
    private JPanel panelS = new JPanel(); 
    private Fibonacci F = new Fibonacci(); 



    public FibonacciJPanel()      //Set up user panel 
    { setLayout(new BorderLayout());    //User BorderLayout 
    panelN.setLayout(new BorderLayout()); 
    panelC.setLayout(new BorderLayout()); 
    panelS.setLayout(new BorderLayout()); 
    panelN.add("North", prompt1);    //Input elements 
    panelN.add("South", inField); 
    panelC.add("West", FibonacciButton);  //Control button 
    panelS.add("North", prompt2);    //Output elements 
    panelS.add("South", resultField); 
    add("North", panelN);      //Input at the top 
    add("Center", panelC);      //buttons in the center 
    add("South", panelS);      //Result at the bottom 
    FibonacciButton.addActionListener(this);   //Register with listeners 
    setSize(175,200); 
    } //FibonacciJPanel 



public void actionPerformed(ActionEvent e) 
    { 
String inputStr = inField.getText();  //user input 
     int userInput = Integer.parseInt(inputStr); //convert to integer 
     boolean result=false; 
    if (e.getSource() == FibonacciButton);   //Process and report 
    { 
      result = fc.sum(userInput); 
      resultField.setText("result"); 

    } //if 
    }//actionPerformed() 
} 

FibonacciJApplet.java

import javax.swing.*; 

public class FibonacciJApplet extends JApplet 
{ public void init() 
    { getContentPane().add(new FibonacciJPanel()); 
    } // init() 
} // Fibonacci class 

Answer 1

喲你不提什麼是你不明白的。

基本上，當你添加一個按鈕時，它知道如何觸發事件，當你點擊它到一個叫做Event Dispatcher Thread（EDT）的線程時。

每當你點擊一個按鈕，這個事件會通知到該按鈕中註冊的每一個「監聽器」（他們正在監聽的通知）

因此，一個簡單的例子是：

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

class Click { 
    public static void main(String ... args) { 
     JButton clickMe = new JButton("Click Me"); 
     ActionListener aListener = new OneActionListener(); 
     clickMe.addActionListener(aListener); 
     JFrame frame = new JFrame(); 
     frame.add(clickMe); 
     frame.pack(); 
     frame.setVisible(true); 
    } 
} 
class OneActionListener implements ActionListener { 
    public void actionPerformed(ActionEvent e) { 
     System.out.printf("Clicked. Thread: %s, action: %s%n", 
      Thread.currentThread().getName(), 
      e.getActionCommand()); 
    } 
} 

這裏你聲明一個實現了ActionListener接口的類OneActionListener讓我知道他可以處理事件的按鈕（用actionPerformed方法）

我希望這個清楚一點這工作。