《Java 核心技術 卷1》 筆記 第11章 異常、日志、斷言和調試（11） 調試器的使用（IDEA環境）

 11.7 使用調試器

❤🧡💛💚💙💜🤎🖤❤🧡💛💚💙💜🤎🖤❤🧡💛💚💙💜🤎🖤

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
public class BuggyButtonTest {
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                BuggyButtonFrame frame = new BuggyButtonFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}
 
class BuggyButtonFrame extends JFrame {
    private static final int W = 300;
    private static final int H = 200;
    public BuggyButtonFrame(){
        setTitle("BuggyButtonTest");
        setSize(W,H);
 
        BuggyButtonPanel panel = new BuggyButtonPanel();
        add(panel);
    }
}
 
class BuggyButtonPanel extends JPanel{
    public BuggyButtonPanel(){
        ActionListener listener = new ButtonListener();
 
        String [] colors = new String[]{"Yellow","Blue","Red"};
        for(int i = 0; i < colors.length; i++){
            JButton b = new JButton(colors[i]);
            add(b);
            b.addActionListener(listener);
        }
    }
 
    private class ButtonListener implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent e) {
            String arg = e.getActionCommand();
 
            String [] colors = new String[]{"yellow","blue","red"};
            Color[] colorObjs = new Color[]{Color.YELLOW,Color.BLUE,Color.RED};
 
            for(int i = 0;i < colors.length; i++){
                if(arg.equals(colors[i])){
                    setBackground(colorObjs[i]);
                }
            }
        }
    }
}      

❤🧡💛💚💙💜🤎🖤❤🧡💛💚💙💜🤎🖤❤🧡💛💚💙💜🤎🖤

🍓 斷點：希望在某一句執行前檢視的位置，點選行号左側，出現紅色小圓圈即可（需要在執行前或執行到這一句前加斷點）

🍓 IDEA 調試方式1：右鍵+DEBUG 按鈕

🍓 IDEA 調試方式2：點選 main 左側小圖示 + DEBUG 按鈕

比如點選這個位置

🍓 檢視參數方式 1：下方控制台 Debug->Debugger->右下角檢視

🍓 檢視參數方式 2：滑鼠光标移動到變量上檢視

此處發現起的名稱不同，把公共名稱改為在外側定義數組，防止重複書寫字元串出錯

❤🧡💛💚💙💜🤎🖤❤🧡💛💚💙💜🤎🖤❤🧡💛💚💙💜🤎🖤

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
public class BuggyButtonTest {
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                BuggyButtonFrame frame = new BuggyButtonFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}
 
class BuggyButtonFrame extends JFrame {
    private static final int W = 300;
    private static final int H = 200;
    public BuggyButtonFrame(){
        setTitle("BuggyButtonTest");
        setSize(W,H);
 
        BuggyButtonPanel panel = new BuggyButtonPanel();
        add(panel);
    }
}
 
class BuggyButtonPanel extends JPanel{
    public BuggyButtonPanel(){
        ActionListener listener = new ButtonListener();
 
        for(int i = 0; i < colors.length; i++){
            JButton b = new JButton(colors[i]);
            add(b);
            b.addActionListener(listener);
        }
    }
 
    final String [] colors = new String[]{"Yellow","Blue","Red"};
    private class ButtonListener implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent e) {
            String arg = e.getActionCommand();
 
            final Color[] colorObjs = new Color[]{Color.YELLOW,Color.BLUE,Color.RED};
 
            for(int i = 0;i < colors.length; i++){
                if(arg.equals(colors[i])){
                    setBackground(colorObjs[i]);
                }
            }
        }
    }
}      

❤🧡💛💚💙💜🤎🖤❤🧡💛💚💙💜🤎🖤❤🧡💛💚💙💜🤎🖤

🍉 小貼士：相似的代碼盡量用循環處理，公共的變量使用全局變量（成員變量）定義