Java重新添加已从JComboBox中删除的项目

Z时代
2024-01-10
分类：问答

我想要做的是只要按下“删除”按钮，它就会删除我在JComboBox中选择的项目。所以一旦我删除所有的项目，我有另一个名为“重置”的按钮，其中所有已删除的项目将再次在JComboBox中，并且有可能有一个恢复方法，而不必重新添加每个模型，导致我的实际的程序有很多模型Java重新添加已从JComboBox中删除的项目

这是我所尝试过的，但它不工作任何建议如何做到这一点？

public class Testing{ 
    JFrame frame; 
    JPanel panel; 
    JButton remove,reset; 
    JComboBox box; 
    final DefaultComboBoxModel items = new DefaultComboBoxModel(new String[] 
    { 
     "-","Database System","Computer Fundamentals", 
     "Computer Maths","Internet Web Tech","Tertiary English 1"        
    }); 
    public void display() 
    { 
     frame = new JFrame(); 
     panel = new JPanel(); 
     box = new JComboBox(); 
     box.setModel(items); 
     remove = new JButton("Remove"); 
     reset = new JButton("Reset"); 
     remove.addActionListener((ActionEvent e)->{ 
     box.removeItem(box.getSelectedItem()); 
     }); 
     reset.addActionListener((ActionEvent e)->{  
     System.out.println("Reset"); 
     box.setModel(items); 
     box.revalidate(); 
     box.repaint(); 
     }); 
     panel.revalidate(); 
     panel.repaint(); 
     panel.add(box); 
     panel.add(remove); 
     panel.add(reset); 
     frame.add(panel); 
     frame.setVisible(true); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setSize(300,300); 
    } 
    public static void main(String[] args) 
    { 
     TestingProgram te = new TestingProgram(); 
     te.display(); 
    } 
}

回答：

我修好了。下面是新的代码：

public class Test{ 
    JFrame frame; 
    JPanel panel; 
    JButton remove,reset; 
    JComboBox box; 
    final DefaultComboBoxModel items = new DefaultComboBoxModel(new String[] 
    { 
     "-","Database System","Computer Fundamentals", 
     "Computer Maths","Internet Web Tech","Tertiary English 1"        
    }); 
    public DefaultComboBoxModel getClone(DefaultComboBoxModel items) { 
     DefaultComboBoxModel clone = new DefaultComboBoxModel(); 
     for(int i = 0;i<items.getSize();i++) { 
      clone.addElement(items.getElementAt(i)); 
     } 
     return clone; 
    } 
    public void display() 
    { 
     frame = new JFrame(); 
     panel = new JPanel(); 
     box = new JComboBox(); 
     box.setModel(getClone(items)); 
     remove = new JButton("Remove"); 
     reset = new JButton("Reset"); 
     remove.addActionListener((ActionEvent e)->{ 
     box.removeItem(box.getSelectedItem()); 
     }); 
     reset.addActionListener((ActionEvent e)->{  
     box.setModel(getClone(items)); 
     }); 
     panel.revalidate(); 
     panel.repaint(); 
     panel.add(box); 
     panel.add(remove); 
     panel.add(reset); 
     frame.add(panel); 
     frame.setVisible(true); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setSize(300,300); 
    } 
    public static void main(String[] args) 
    { 
     Test te = new Test(); 
     te.display(); 
    } 
}