Why not set bounds of the JPanel?

Question

import java.awt.*;
import java.util.*;
import javax.swing.*;
import java.awt.event.*;
public class ResLoadChart extends JPanel {
private Vector vName;     
private int[] vLoad;     
private int iSlotSize;     
private int yslots=6, xslots, iaYpegs[], maxY=6;
private int t_margin=40, b_margin=60, l_margin=60, r_margin=80;
private String t_title = "Work";
private String l_title = "No of Minutes";
private String m_resType = null;
private JPanel m_bars[];
public ResLoadChart(String resType, Vector vName,int[] vLoad) {
     t_title = t_title + resType;
     m_resType = resType;
     this.vName=vName;
     this.vLoad=vLoad;
xslots = vName.size();
init();
public void init(){
     m_bars = new JPanel[xslots];
     Random ran=new Random();
     for (int i=0; i<xslots; i++) {
          m_bars[i] = new JPanel();
          m_bars.setOpaque (false);
          m_bars[i].setBackground (new Color(ran.nextInt(256), ran.nextInt(256), ran.nextInt(256)));
          add (m_bars[i]);
loadBars();
     loadChart ();
public void loadChart () {
setSlotSize ();
private void setSlotSize() {
maxY=6;
calculate();
private void calculate() {
int i, j;
int pegs[]=new int[xslots];
for(i=0; i<xslots; i++) {
     pegs[i] = vLoad[i];
maxY=(pegs[i]>maxY) ? pegs[i]:maxY;
iaYpegs=pegs;
private void loadBars () {
calculate();
     int sx, ex, sy, ey;
     Rectangle rect=getBounds();
     sx=l_margin;
ex=rect.width-r_margin;
sy=t_margin;
ey=rect.height-b_margin;
int wd=(ex-sx)/xslots;
for(int i=0; i<xslots; i++) {
m_bars[i].setBounds (sx+(ex-sx)*i/xslots, ey-(ey-sy)*iaYpegs[i]/maxY, wd, (ey-sy)*iaYpegs[i]/maxY);
m_bars[i].setToolTipText ((String)vName.get(i)+": " + vLoad[i]);
when I run ,throws Exception:
java.lang.nullPointerException at LoadChartGui.ResLoadChard.loadBars
I donnt know what is the matter in this class?

Answer 1

To me, it sounds like it's a marketing scheme, for developers to make iPhone applications, and a separated iPad application.
That is not the case. It's up to the developers to decide if they make separate iPhone/iPad apps or one app that can fit both displays. The biggest problem is that iPhones prior to iPhone 4 have different hardware and are not capable of producing the same screen resolutions as the iPad, so it's not possible to make a single app that will work on both with equal results.
The 2X zoom feature is provided on the iPad to compensate for the lower resolution of iPhone apps, and there is no way to increase the resolution of an app that was made for the previous generation iPhones.