Exception in thread "main" java.lang.NullPointerException
at java.awt.Container.addImpl(Unknown Source)
at java.awt.Container.add(Unknown Source)
at sudoku.buildSudoku_pane(sudoku.java:25)
at sudoku.<init>(sudoku.java:31)
at sudoku.main(sudoku.java:46)
Code: Select all
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.lang.*;
import java.io.*;
import java.util.*;
import java.lang.Character;
public class sudoku extends JFrame implements ActionListener{
private JFrame sudoku_frame = new JFrame("Sudoku");
private JButton solve;
private JButton check_if_correct;
private JTextField[] sudoku_entry;
public final static boolean RIGHT_TO_LEFT = false;
public void actionPerformed(ActionEvent e) {}
private void buildSudoku_pane(int number, Container pane, JTextField[] sudoku_entry_array){
sudoku_entry_array = new JTextField[number*number];
if (RIGHT_TO_LEFT){
pane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
}
pane.setLayout(new GridLayout(number,number));
for(int i = 0; i <= (number*number)-1; i++){
pane.add(sudoku_entry_array[i]);
}
}
public sudoku() {
int int_default = 9;
buildSudoku_pane(int_default, sudoku_frame.getContentPane(), sudoku_entry);
sudoku_frame.pack();
sudoku_frame.setVisible(true);
}
public sudoku(int number){
buildSudoku_pane(number, sudoku_frame.getContentPane(), sudoku_entry);
sudoku_frame.pack();
sudoku_frame.setVisible(true);
}
public static void main(String[] args) {
sudoku tpo = new sudoku(); // create 'the program object'
tpo.addWindowListener(new WindowAdapter() { // this exits the program when X box clicked
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
} // end of main
}