Error: unable to initialize the main class SimpleGUI
Reason: the Java. Lang. NoClassDefFoundError: myDrawPanel (wrong name: myDrawPanel)

Code purpose: to display a panel with a random color circle and a button, click on the button, change color,
How do I modify the code?

 import javax.mail. Swing. *; 
import java.awt.*; 
Import the Java. The awt. Event. An ActionEvent; 
Import the Java. The awt. Event. ActionListener; 

The class MyDrawPanel extends JPanel {
Public void paintComponent (Graphics g) {
Graphics2D Graphics2D=g (Graphics2D); 
Int red=(int) (Math. The random () * 255); 
Int green=(int) (Math. The random () * 255); 
Int blue=(int) (Math. The random () * 255); 
Color startColor=new Color (red, green, blue); 

Red=(int) (Math. The random () * 255); 
Green=(int) (Math. The random () * 255); 
Blue=(int) (Math. The random () * 255); 
Color endColor=new Color (red, green, blue); 

GradientPaint GradientPaint=new GradientPaint (70, startColor, 150150, endColor); 
Graphics2D. SetPaint (gradientPaint);//the virtual brush painting gradually layer 
Graphics2D. FillOval,70,100,100 (70);//use the brush to fill the oval area 
} 
} 

Public class SimpleGUI implements ActionListener {

JFrame frame; 

Public static void main (String [] args) {
SimpleGUI GUI=new SimpleGUI (); 
GUI. The go (); 
} 

Public void actionPerformed (an ActionEvent event) {
Frame. The repaint (); 
} 

Public void the go () {
Frame=new JFrame (); 
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//set off or stop 

JButton button=new JButton (" do not click "); 
Button. AddActionListener (this); 
MyDrawPanel drawPanel=new MyDrawPanel ();//create our myPanel object 

Frame. The add (BorderLayout. CENTER, drawPanel);//add into the frame of the frame 
Frame. The add (BorderLayout. SOUTH, the button). 

Frame. The setSize (300300); 
frame.setVisible(true);//set the framework for visible 
} 

} 

CodePudding user response:

1. Use your code has achieved what you want without abnormal function
2. May be your eclipse or other compilation tools version is too low