在封闭范围内定义的局部变量num必须是最终的或有效的最终

Question

单击删除button时，我希望它显示检查哪个checkbox。但是，它们是在之下的一条红线，号码为，这是删除button的代码。

for(int i=0;i<num;i++) 

deleteAdmin.java

public deleteAdmin() 
    { 
     int num=0; 

     JButton back= new JButton("Back"); 
     JButton delete= new JButton("Delete"); 

     JPanel topPanel = new JPanel(new GridLayout(1, 0, 3, 3)); 
     topPanel.add(back); 
     topPanel.add(delete); 


     adminAPI admin = new adminAPI(); 
     List<String>allName = null; 

     try { 
      allName= admin.displayName(); // retrieve all names from MySQL and store to list 
      num= admin.displayCheckBoxAndLabel(); // get total row numbers 
     } catch (Exception e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
     } 
     Object [] o1=allName.toArray(); // convert arrayList to array 
     JCheckBox[] checkBoxList = new JCheckBox[num]; 

     JPanel checkBoxPanel= new JPanel(new GridLayout(0,5,5,5)); 
     for(int i = 0; i < num; i++) { 
      checkBoxList[i]= new JCheckBox(""+o1[i]); // replace each checkbox with name 
      checkBoxPanel.add(checkBoxList[i]); 

     } 

      delete.addActionListener(new ActionListener(){ // if delete button clicked 
       public void actionPerformed(ActionEvent e) 
       { 
        for(int i=0;i<num;i++) 
        { 
         if(checkBoxList[i].isSelected()) 
          System.out.println(i); 
        } 
       } 


      }); 

     setLayout(new BorderLayout(5, 5)); 
      add(topPanel, BorderLayout.PAGE_START); 
      add(checkBoxPanel, BorderLayout.CENTER); 
      setBorder(BorderFactory.createEmptyBorder(2, 2, 2, 2)); 

    } 

错误

Exception in thread "AWT-EventQueue-0" java.lang.Error: Unresolved compilation problem: Local variable num defined in an enclosing scope must be final or effectively final at gui.deleteAdmin$1.actionPerformed(deleteAdmin.java:86)

我是否正确地实现它？

Answer 1

声明此

int num; 

为类变量和初始化它在

public deleteAdmin() 
    { 
     num=0;