Null Pointer Exception?

import javax.swing.*;import java.awt.*;import java.awt.event.*;import java.lang.Math.*;import java.math.*; import java.text.*;import java.io.*;import java.util.*;public class InvGUI extends JFrame								{	//Instantiate new arrays	static private int[] itemNumber = new int[7];	static private String[] itemName = new String[7];	static private int[] inStock = new int[7];	static private double[] manufPrice = new double[7];	static private double[] sellingPrice = new double[7];	static private Inventory[] inv = new Inventory[7];	//create ButtonHandlers	//private PrintButtonHandler pbHandler;   private ExitButtonHandler ebHandler;		//private SellButtonHandler sbHandler;	private SortButtonHandler sortbHandler;	//set GUI width and Height   private static final int WIDTH = 600;   private static final int HEIGHT = 400;					//Create JLabels	private JLabel itemsInStoreL;		//Create JTextFields	private JTextArea mainTextTA, reportTextTA;		//Create Jbuttons	private JButton sortB /*sellB*/, printB, exitB;	//private ButtonHandler bHandler;    public InvGUI()				    {	 		setTitle("Inventory"); 					//set the window title			setSize(WIDTH, HEIGHT);					//set the window size			Container pane = getContentPane();	//get the container			pane.setLayout(null);	//set container layout to null            // Create labels				itemsInStoreL= new JLabel( "The Items in the store",SwingConstants.LEFT);             //Create   textfields				mainTextTA = new JTextArea(8, 20);				reportTextTA = new JTextArea(8, 20);								//Create Print Button		 	   //printB = new JButton("Print Report");    	      //pbHandler = new PrintButtonHandler();		   	//printB.addActionListener(pbHandler);												//create Sell Button				 //  sellB = new JButton("Sell Item");        	 //	sellbHandler = new SellButtonHandler();		    //	sellB.addActionListener(sbHandler);	            //create Sort Button       	 	sortB = new JButton("Sort By Name");        	 	sortbHandler = new SortButtonHandler();		    	sortB.addActionListener(sortbHandler);            //Create Exit Button 		  		exitB = new JButton("Exit");        		ebHandler = new ExitButtonHandler();		  		exitB.addActionListener(ebHandler);								//set the size of the labels, text fields, and buttons				itemsInStoreL.setSize(200, 30);				mainTextTA.setSize(370, 120);				reportTextTA.setSize(370,120);				sortB.setSize(100, 30);				//sellB.setSize(100, 30);				printB.setSize(100, 30);				exitB.setSize(100, 30);				                   //set the locations				itemsInStoreL.setLocation(220, 10);				mainTextTA.setLocation(20, 40);				sortB.setLocation(500, 40);				//sellB.setLocation(500, 80);				printB.setLocation(500, 120);				exitB.setLocation(500, 160);								//add the labels, text fields, and buttons				pane.add(itemsInStoreL);				pane.add(mainTextTA);				pane.add(reportTextTA);				pane.add(sortB);				//pane.add(sellB);				pane.add(printB);				pane.add(exitB);            		setVisible(true);   //see the window      setDefaultCloseOperation(EXIT_ON_CLOSE); //exit on close    } 		//create main method    public static void main(String[] args)										throws FileNotFoundException    {        InvGUI inventory = new InvGUI();		  		  Scanner inFile = new Scanner ( new FileReader("final.txt"));		  		  for (int i = 0; i < itemNumber.length; i++)		  {		  	itemNumber = inFile.nextInt();			inFile.nextLine();  //dummy read			itemName = inFile.nextLine();			inStock = inFile.nextInt();			manufPrice = inFile.nextInt();			sellingPrice = inFile.nextInt();			  }				  for (int i = 0; i < inv.length; i++)		  	{				inv.setI(itemName, itemNumber, inStock, inStock, 0,																					 manufPrice, sellingPrice);			}	  			    }	 		 	 	//print button handler	private class PrintButtonHandler implements ActionListener	{	  reportTextTA.setText(printInv());	}		//private class SellButtonHandler implements ActionListener	//{	 		//}		 	 	 	//sort Button handler	 private class SortButtonHandler implements ActionListener    {        public void actionPerformed( ActionEvent e)     			{       			String temp;        			int counter, index;        				for (counter = 0; counter < itemName.length - 1; counter++)        				{            			for (index = 0; index < itemName.length - 1 - counter;                            												index++)               			if (itemName[index].compareTo(itemName[index + 1]) > 0 )               	 		{               	     		temp = itemName[index];                 	   		itemName[index] = itemName[index + 1];                 	   		itemName[index + 1] = temp;                			}       	 			}	     				}    }			private class ExitButtonHandler implements ActionListener    {        public void actionPerformed( ActionEvent e)        {            System.exit(0);        }    }	 }

for (int i = 0; i < inv.length; i++){    int itemNumber = inFile.nextInt();    inFile.nextLine();  //dummy read    String itemName = inFile.nextLine();    int inStock = inFile.nextInt();    int manufPrice = inFile.nextInt();    int sellingPrice = inFile.nextInt();    inv.setI(itemName, itemNumber, inStock, inStock, 0, manufPrice, sellingPrice);	}

import javax.swing.*;import java.awt.*;import java.awt.event.*;import java.lang.Math.*;import java.math.*; import java.text.*;import java.io.*;import java.util.*;import java.util.Arrays.*;import java.util.Collections.*;import java.util.List.*;public class InvGUI extends JFrame								{	//Instantiate new arrays	//static private int[] itemNumber = new int[7];	//static private String[] itemName = new String[7];	//static private int[] inStock = new int[7];	//static private double[] manufPrice = new double[7];	//static private double[] sellingPrice = new double[7];	//static private Inventory[] inv = new Inventory[7];	//create ButtonHandlers	private PrintButtonHandler pbHandler;   private ExitButtonHandler ebHandler;		//private SellButtonHandler sbHandler;	//private SortButtonHandler sortbHandler;	//set GUI width and Height   private static final int WIDTH = 600;   private static final int HEIGHT = 400;					//Create JLabels	private JLabel itemsInStoreL;		//Create JTextFields	private JTextField sellTF;		//Create JTextAreas	private JTextArea mainTextTA, reportTextTA;		//Create Jbuttons	private JButton sortB, sellB, printB, exitB;	//private ButtonHandler bHandler;    public InvGUI()				    {	 		setTitle("Inventory"); 					//set the window title			setSize(WIDTH, HEIGHT);					//set the window size			Container pane = getContentPane();	//get the container			pane.setLayout(null);	//set container layout to null            // Create labels				itemsInStoreL= new JLabel( "The Items in the store",SwingConstants.LEFT);								//create textfields 				sellTF = new JTextField(10);            //Create   textareas				mainTextTA = new JTextArea(10, 10);				reportTextTA = new JTextArea(10, 10);								//Create Print Button		 	   printB = new JButton("Print Report");    	      pbHandler = new PrintButtonHandler();		   	printB.addActionListener(pbHandler);												//create Sell Button				 //  sellB = new JButton("Sell Item");        	 //	sellbHandler = new SellButtonHandler();		    //	sellB.addActionListener(sbHandler);	            //create Sort Button       	 	//sortB = new JButton("Sort By Name");        	 	//sortbHandler = new SortButtonHandler();		    	//sortB.addActionListener(sortbHandler);            //Create Exit Button 		  		exitB = new JButton("Exit");        		ebHandler = new ExitButtonHandler();		  		exitB.addActionListener(ebHandler);								//set the size of the labels, text fields, and buttons				itemsInStoreL.setSize(200, 30);				mainTextTA.setSize(370, 120);				reportTextTA.setSize(370,120);				sellTF.setSize(100, 100);				sortB.setSize(100, 100);				//sellB.setSize(100, 30);				printB.setSize(100, 30);				exitB.setSize(100, 30);				                   //set the locations				itemsInStoreL.setLocation(220, 10);				mainTextTA.setLocation(20, 40);				sortB.setLocation(500, 40);				//sellB.setLocation(20, 200);				sellTF.setLocation(130, 200);				printB.setLocation(500, 120);				exitB.setLocation(500, 160);								//add the labels, text fields, and buttons				pane.add(itemsInStoreL);				pane.add(mainTextTA);				pane.add(reportTextTA);				pane.add(sortB);				//pane.add(sellB);				pane.add(sellTF);				pane.add(printB);				pane.add(exitB);            		setVisible(true);   //see the window      setDefaultCloseOperation(EXIT_ON_CLOSE); //exit on close    } 		//create main method    public static void main(String[] args)										throws FileNotFoundException    {        InvGUI inventory = new InvGUI();		  		  Inventory[] inv = new Inventory[7];		  		  Scanner inFile = new Scanner ( new FileReader("final.txt"));		  		  for (int i = 0; i < inv.length; i++)		   {			 int itemNumber = inFile.nextInt();			 inFile.nextLine(); //dummy read			 String itemName = inFile.nextLine();			 int inStock = inFile.nextInt();			 int manufPrice = inFile.nextInt();			 int sellingPrice = inFile.nextInt();			 			 inv.setI(itemName, itemNumber, inStock, inStock, 0, manufPrice, sellingPrice);						}   			    }	 		 	 	//print button handler	private class PrintButtonHandler implements ActionListener	{     public void actionPerformed( ActionEvent e)			{		if (e.getActionCommand().equals("Print Report"))			reportTextTA.setText(toString());		}	}	/*	private class SortButtonHandler implements ActionListener    {        public void actionPerformed( ActionEvent e)     			{					Arrays.sort(inv[]);				}	 }*/		//private class SellButtonHandler implements ActionListener	//{	 		//}		 	 	 	//sort Button handler	/* private class SortButtonHandler implements ActionListener    {        public void actionPerformed( ActionEvent e)     			{       			String temp;        			int counter, index;        				for (counter = 0; counter < itemName.length - 1; counter++)        				{            			for (index = 0; index < itemName.length - 1 - counter;                            												index++)               			if (itemName[index].compareTo(itemName[index + 1]) > 0 )               	 		{               	     		temp = itemName[index];                 	   		itemName[index] = itemName[index + 1];                 	   		itemName[index + 1] = temp;                			}       	 			}	     				}    }	*/		private class ExitButtonHandler implements ActionListener    {        public void actionPerformed( ActionEvent e)        {            System.exit(0);        }    }	 	 }