JButton 在鼠标悬停之前不可见

Question

I'm creating a gui for my project. When the gui is first loaded only background is visible, so buttons are not visible, but when mouse over them, they are visible. What is the solve this problem?

public class Home extends JFrame{
//New JPanel 
private JPanel home;

//Creating image url. You must be change url
ImageIcon icon = new ImageIcon("img//home1.jpeg");

//Home Class
public Home(){

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 960, 640);
    setTitle("LoneyTunes Crush");
    home = new JPanel();
    home.setBorder(new EmptyBorder(5, 5, 5, 5));
    home.setLayout(new BorderLayout(0, 0));
    setContentPane(home);

    getContentPane().setLayout(null);
    JLabel background = new JLabel(new ImageIcon("img//giphy."));
    getContentPane().add(background);
    background.setLayout(new FlowLayout());

        //Creating Buttons
    JButton play = new JButton("Play");
    play.setBounds(20, 20, 200, 30);
    JButton setting = new JButton("Settings");
    setting.setBounds(20, 60, 200, 30);
    JButton exit = new JButton("Exit");
    exit.setBounds(20, 100, 200, 30);
       //Adding Buttons
    home.add(play);
    home.add(setting);
    home.add(exit);

            //ActionListeners
    play.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
               home.setVisible(false);
               difficulty.setVisible(true);

            }

          });

    exit.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e){
            System.exit(1);   

            }

          });


    validate();


}

//Background paint method
public void paint(Graphics g){

    g.drawImage(icon.getImage(), 0, 0, getWidth(), getHeight(), null);


}   

}

Main Class

public class MainClass {
public static Home pencere;

public static void main(String args[]){
    pencere=new Home();
    pencere.setVisible(true);
}

}

Answer 1

1. Don't paint on top-level containers like JFrame as they already carry the burden of painting all of it's components.

2. Instead paint on JPanel or JComponent and Override it's paintComponent method.

3. On top of overriding paintComponent (or in your case paint ), you need to also call super.paintComponent (in your case super.paint ) inside the the method (first call under the method signature), as to not break the paint chain. Failing to do so may and probably will leave you with undesired paint artifacts.

4. Avoid using null layouts for a number of reason. Different platform will treat them differently. They are difficult to maintain, among many other reasons. Instead use layout managers, and let them do the laying out and sizing of the components, as they were designed to do with Swing apps. Learn more at Laying out components Within a Container

5. Setting Home pancere as a static class member of MainClass is completely pointless. Just declare and instantiate both in the main method.

6. Swing apps should be run on the Event Dispatch Thread (EDT). You can do so by wrapping your the code inside your main method with a SwingUtilities.invokeLater... . See more at Initial Threads

7. Instead of trying to make panels visible and not visible or adding an removing panel, consider using a CardLayout which will "layer" panels, and you can navigate through them with CardLayout 's methods like show() , next() , previous() . See more at How to Use CardLayout

8. By time of deployments, the images you are using will need to become embedded resources, and should be loaded from the class path, and not from the file system. When you pass a String to ImageIcon , you are telling the program to look in the file system, which may work in your development environment, but that's it. See the wiki tag on embedded-resource an pay close attention to the very last link that will provide you will some resources on how to use and load embedded resources if the info doesn't provide enough detail.

Answer 2

Problem is with

 getContentPane().setLayout(null);

remove it as you have already set the layout to a Border Layout and you will see all these buttons.

Answer 3

只要确保除了你想要显示的面板之外的所有其他面板的可设置性设置为假。我也有类似的问题，但我忘了将10个面板中的一个面板的可见性设置为false。问题解决了一旦我设置它是假的。

Answer 4

I don't know how this worked for me I just typed jf.setVisible(true); at the end after adding all the GUI codes... `

public Calculator(){

        jf = new JFrame("Basic Calculator");
        jf.setLayout(GridBagLayout);
        jf.setSize(306, 550);
        jf.setLocation(530, 109);

    > all the GUI things like JButton, JLabel, etc...

jf.setVisible(true); jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

I dont know how to type a perfect reply 'cause I am replying for the first time in stackoverflow.. SORRY!!

Answer 5

Try putting validate(); method on your main frame. I think it would help you.