如何在Java中获得面板的大小？

Question

我尝试使用panel.getSize（），但它说java.awt.dimension [width = 0，高度= 0]

我尝试了panel.getheight （），但它说是0

Answer 1

您获得0x0尺寸的原因是：

您确实声明了比Jframe和Jpanel更早发现尺寸的

我这样做的：

JPanel panel = new JPanel();
System.out.println(panel.getSize()); // <-- This Line Triggers Earlier
panel.setVisible(true); // <-- Then This Line Renders the Panel, but late to recognize

要解决此问题，请确保在获取大小的信息之前先渲染所有对象

JPanel panel = new JPanel();
panel.setVisible(true); // <-- Then This Line Renders the Panel first before recognizing
System.out.println(panel.getSize()); // <-- This Line Triggers Output Size

：您的选择，我的实例是Mouselistener）：

 import java.awt.Event.*;

        panel.addMouseListener(new MouseAdapter() {
        
        @Override
        public void mousePressed(MouseEvent me) {
          System.out.println("Size: " + panel.getSize());
            panel.repaint(); //This refreshes when user tries to resize
        }
    });

用于示例：

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

class Main {
  public static void main(String[] args) {
    JFrame frame = new JFrame("Hello world");
    frame.setSize(300, 300);
    frame.setLocation(5, 5);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //JPanel Created
    JPanel panel = new JPanel();
    //You are getting 0x0 because you did first
    //System.out.println("Size: " + panel.getSize());
    panel.setVisible(true);
    frame.add(panel);
    frame.setVisible(true);
    
    //Solution: Get Value by event of your choice
    //My instance is to use mouseListener mousePressed
    panel.addMouseListener(new MouseAdapter() {
    
    @Override
    public void mousePressed(MouseEvent me) {
      System.out.println("Size: " + panel.getSize());
        panel.repaint();
    }
});
  }
}

如果有帮助的话，请竖起大拇指。 gladge