java - Jlabel图像/ImageIcon

Question

这个问题已经有答案了:

What is a NullPointerException, and how do I fix it? (12 个回答)

已关闭 6 年前。

我试图向这些标签添加一些图像，但 Eclipse 抛出 java.lang.NullPointerException，我不知道为什么？!请帮忙:}

public class LabelPanel extends JPanel {                

      public JLabel[] bills;                        

      public LabelPanel() {                  
           setLayout(new FlowLayout());                                                                   
           init();               
           labelOrder();            
      }                         


      private void init() {                 
          bills = new JLabel[4];                    
           for (int i = 0; i < bills.length; i++){                                                       
               bills[0].setIcon(newImageIcon("C:\\users\\Acer\\Documents\\images\\1.jpg"));                                 
               bills[1].setIcon(new ImageIcon("C:\\Users\\Acer\\Documents\\images\\2.jpg"));                        
               bills[2].setIcon(new ImageIcon("C:\\Users\\Acer\\Documents\\images\\5.jpg"));                        
               bills[3].setIcon(new ImageIcon("C:\\Users\\Acer\\Documents\\images\\10.jpg"));                       
               bills[4].setIcon(new ImageIcon("C:\\Users\\Acer\\Documents\\images\\20.jpg"));                   
           }                            
       }    

      private void labelOrder() {                               
           add(bills[0]);               
           add(bills[1]);               
           add(bills[2]);               
           add(bills[3]);               
           add(bills[4]);               
       }  
  }

Answer 1

尝试以下代码

示例代码

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.FlowLayout;

    public class SwingExampleDemo {  
      public static void main(String[] args) {  
          JFrame f=new JFrame();//creating instance of JFrame 
          ImageIcon imageIcon = new ImageIcon("C:\\users\\Acer\\Documents\\images\\1.jpg"); //here image path 
          JLabel jLabel = new JLabel(imageIcon);    
          f.add(jLabel);         
          f.setLayout(new FlowLayout());//using layout managers  
          f.setVisible(true);//making the frame visible  
          f.pack();
       }  
    }

希望对你有帮助...