Null Pointer Exception in an Array of JCheckBoxes

[eLancaster]

So I have an array of 7 checkboxes with the names of consecutive days next to them. The program checks off the days how many consecutive days the program was run.

I get a null pointer exception when i initialize the array of JCheckBoxes (in REd below). I'm noe sure how to fix it. Could use a little help and explanation of what I did wrong, thanks!!

import java.util.Calendar;
import java.util.Formatter;
import java.util.Scanner;

import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JOptionPane;


public class ConsecutiveLaunch extends JFrame{
	[B]private JCheckBox[] launchCheckBox = new JCheckBox[6];
	private int today;
	private int consecutiveLaunchesNumber;
	private int yesterday;[/B]
	
	[B]private void getToday()[/B]
	{
            //use calendar function to get numerical value of today and stores it in this.today
	}
	[B]public int getDayAfterToday(int daysAfterToday)[/B]
	{
	//returns the numerical value of the day = today+daysAfterToday.
 
	}
	
	[B]public String toString(int day)[/B]
	{
          //converts the numerical values of day into a string e.g. 2 = "Monday"
	}
	
	[B]private void readLaunchRecords()[/B]
	{
//reads the last day of launch and consecutiveLaunchesNumber
//sets this.yesterday = last day of launch
//sets this.consecutiveLaunchesNumber = consecutiveLaunchesNumber from file.
	}
	
	[B]private void writeLaunchRecords()[/B]
	{
//writes this.today and update consecutiveLaunchesNumber onto file.
	}
	
	[B]private boolean isLaunchConsecutive()[/B]
	{
//checks to see if launches are consecutive
	}
	
	[B]private void displayConsecutiveLaunches()[/B]
	{
		for(int index=0;index<=this.consecutiveLaunchesNumber;index++)
		{
			launchCheckBox[index].setSelected(true);
		}
	}
	
	[B]private void createLaunchRecords()[/B]
	{
//writes launch Records if they don't already exist
	}
	
	[B]public ConsecutiveLaunch()[/B]
	{
		super("Consecutive Launch Bonus");
		this.getToday();
		
		readLaunchRecords();
		
		
		if(isLaunchConsecutive()==true)
		{
			this.consecutiveLaunchesNumber++;
		}else
		{
			this.consecutiveLaunchesNumber=1;
		}
		
		writeLaunchRecords();

		for(int index=0;index<launchCheckBox.length;index++)
		{
			[COLOR="Red"][B]launchCheckBox[index] = new JCheckBox(toString(getDayAfterToday(index++)));//NULL POINTER EXCEPTION!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!![/B][/COLOR]
			launchCheckBox[index].setEnabled(false);
			add(launchCheckBox[index]);
		}
		
		displayConsecutiveLaunches();
	}
}

[Fubarable]

You should avoid trying to mess with a for loops index from within the for loop itself.

		for(int index=0;index<launchCheckBox.length;index++)
		{
			launchCheckBox[index] = new JCheckBox(toString(getDayAfterToday(index++)));

In the block of code above you have index++, but the index is already being incremented by the for loop itself, so you will mess up the loop by doing this.

[eLancaster]

Yeah, I realized that and then fixed it and that problem got solved.

But I have another issue - when I run the program, it only shows one day "Thursday" and marks it unchecked. I don't understand why it only shows one day. I've worked through the code and it should show all 7 checkboxes with their respective days.

Could you help me out with that

P.S. sorry for marking the thread as solved when it isn't ...yet.

[Fubarable]

Can't help you yet, as your code is incomplete -- you have method bodies that you have left blank.

[eLancaster]

I just noticed it - it was because i hadn't imported FlowLayout().
Thanks alot for your help :) !