Java simple rgb to hex converter

Complete source code below is a small java program that convert rgb value to hex value. Now i will share with you how to get hex value from rgb value. Before i go far, let we see a description about hex value structure.

VALUE THAT YOU GET AFTER DIVIDE OR MULTIPLY	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
HEX VALUE	0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F

TABLE A

For example :
FFFFFF is a hex value for white and it's rgb value is 255 255 255.First FF is value for red, second FF is value for green and last FF is for blue.So it mean, first 255 in rgb is equal to first FF in hex value.Now i will show you, how to get FF from 255.For this tutorial i show you only for red part. You can try other last two part for green and blue. Now take 255 and devide it with 16. You should get 15.9375. Take value before floating point. In this case we get 15. Look at TABLE A at above. 15 is equal to F. Now you get first F.For second F, take value after floating point and multiply it with 16. In this case you should multiply 0.9375 with 16. It's result is equal to 15 and it also hold F.Now you get hex value for red part.I hope you can understand what i tried to say.

********************************************************************
COMPLETE SOURCE CODE FOR : RGBtoHEX.java
********************************************************************

::Click Here To Download This Java Source Code::

import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;

import java.awt.GridLayout;
import java.awt.Color;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class RGBtoHEX implements ActionListener
{
JTextField r=new JTextField(10);
JTextField g=new JTextField(10);
JTextField b=new JTextField(10);

JLabel rLabel=new JLabel("R",JLabel.CENTER);
JLabel gLabel=new JLabel("G",JLabel.CENTER);
JLabel bLabel=new JLabel("B",JLabel.CENTER);

JPanel panelTextField=new JPanel();
JPanel panelLabel=new JPanel();

JButton button=new JButton("Calculate Now !");

JTextField result=new JTextField(30);

public RGBtoHEX()
{
button.addActionListener(this);

r.setHorizontalAlignment(JTextField.CENTER);
g.setHorizontalAlignment(JTextField.CENTER);
b.setHorizontalAlignment(JTextField.CENTER);

result.setHorizontalAlignment(JTextField.CENTER);
result.setBackground(new Color(255,255,255));
result.setEditable(false);

panelLabel.setLayout(new GridLayout(1,3));
panelLabel.add(rLabel);
panelLabel.add(gLabel);
panelLabel.add(bLabel);

panelTextField.setLayout(new GridLayout(1,3));
panelTextField.add(r);
panelTextField.add(g);
panelTextField.add(b);

JFrame myMainWindow=new JFrame("RGB to HEX");
myMainWindow.getContentPane().setLayout(new GridLayout(4,1));
myMainWindow.getContentPane().add(panelLabel);
myMainWindow.getContentPane().add(panelTextField);
myMainWindow.getContentPane().add(button);
myMainWindow.getContentPane().add(result);

myMainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myMainWindow.setSize(300,130);
myMainWindow.setLocationRelativeTo(null);
myMainWindow.setVisible(true);
}

public void actionPerformed(ActionEvent event)
{
try
{
String hexValue="#";
r.setEditable(false);
g.setEditable(false);
b.setEditable(false);

double red=Double.parseDouble(r.getText());
double green=Double.parseDouble(g.getText());
double blue=Double.parseDouble(b.getText());

for(int i=1;i<=3;i++)
{
double temp=0;

if(i==1)
{
 temp=red;
}
else if(i==2)
{
 temp=green;
}
else if(i==3)
{
 temp=blue;
}

double devideResult=temp/16;

String stringDevideResult=Double.toString(devideResult);

int pointIndexInString=stringDevideResult.indexOf(".");

String firstValue=stringDevideResult.substring(0,pointIndexInString);

double multiplySixteen=(devideResult-(Double.parseDouble(firstValue)))*16;

String stringMultiplySixteen=Double.toString(multiplySixteen);

pointIndexInString=stringMultiplySixteen.indexOf(".");

String secondValue=stringMultiplySixteen.substring(0,pointIndexInString);

if(firstValue.equalsIgnoreCase("10"))
{
 firstValue="A";
}
if(firstValue.equalsIgnoreCase("11"))
{
 firstValue="B";
}
if(firstValue.equalsIgnoreCase("12"))
{
 firstValue="C";
}
if(firstValue.equalsIgnoreCase("13"))
{
 firstValue="D";
}
if(firstValue.equalsIgnoreCase("14"))
{
 firstValue="E";
}
if(firstValue.equalsIgnoreCase("15"))
{
 firstValue="F";
}
if(secondValue.equalsIgnoreCase("10"))
{
 secondValue="A";
}
if(secondValue.equalsIgnoreCase("11"))
{
 secondValue="B";
}
if(secondValue.equalsIgnoreCase("12"))
{
 secondValue="C";
}
if(secondValue.equalsIgnoreCase("13"))
{
 secondValue="D";
}
if(secondValue.equalsIgnoreCase("14"))
{
 secondValue="E";
}
if(secondValue.equalsIgnoreCase("15"))
{
 secondValue="F";
}

hexValue=hexValue+firstValue+secondValue;
}


result.setText(hexValue);
r.setEditable(true);
g.setEditable(true);
b.setEditable(true);
}
catch(Exception exception)
{
JOptionPane.showMessageDialog(null,"Program error and it will terminate","ERROR",JOptionPane.ERROR_MESSAGE);
System.exit(0);
}
}

public static void main(String[]args)
{
RGBtoHEX converter=new RGBtoHEX();
}
}

********************************************************************
JUST COMPILE AND EXECUTE IT
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Java simple image magnifier tooltip

Sometime when we play with images...i mean here a lot of images, like we let user choose an image from 500 images in a JFrame and all images show at the same time without any scrollbar, it can give user a little problem if the image too small. So, how can user make a good choice. This give me some idea to built my own image tooltip. This is a simple tooltip. It will enlarge image when someone hover mouse cursor on it.Image below is a result from program below.

Before you compile and execute it, you should download all images below. After that place them at same location with this java source file.

Love_Music_by_jovincent.jpg

Leafs_1_by_NerghaL.jpg

Hancock-1611.jpg

matrix.jpg

********************************************************************
COMPLETE SOURCE CODE FOR : ImageToolTip.java
********************************************************************

::Click Here To Download File For This Tutorial::

import javax.swing.JPanel;
import javax.swing.ImageIcon;
import javax.swing.JFrame;

import java.awt.GridLayout;
import java.awt.Graphics;

import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;

public class ImageToolTip
{
public static void main(String[]args)
{
 PanelImage imageA=new PanelImage("matrix.jpg");

 PanelImage imageB=new PanelImage("Hancock-1611.jpg");

 PanelImage imageC=new PanelImage("Leafs_1_by_NerghaL.jpg");

 PanelImage imageD=new PanelImage("Love_Music_by_jovincent.jpg");

 JFrame myMainWindow=new JFrame("Image Tool Tip");
 myMainWindow.setResizable(false);
 myMainWindow.getContentPane().setLayout(new GridLayout(2,2));
 myMainWindow.getContentPane().add(imageA);
 myMainWindow.getContentPane().add(imageB);
 myMainWindow.getContentPane().add(imageC);
 myMainWindow.getContentPane().add(imageD);

 myMainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 myMainWindow.setSize(100,100);
 myMainWindow.setLocationRelativeTo(null);
 myMainWindow.setVisible(true);
}
}

class PanelImage extends JPanel implements MouseListener
{
ImageIcon temp;
ImageMagnifier im;

public PanelImage(String a)
{
 addMouseListener(this);
 temp=new ImageIcon(a);
}

public void paint(Graphics g)
{
 super.paint(g);
 g.drawImage(temp.getImage(),0,0,getSize().width,getSize().height,this);
}

public void mouseClicked(MouseEvent event)
{
}

public void mouseEntered(MouseEvent event)
{
 im=new ImageMagnifier(temp,getSize().width,getSize().height,event.getXOnScreen(),event.getYOnScreen());
}

public void mouseExited(MouseEvent event)
{
 im.dispose();
}

public void mousePressed(MouseEvent event)
{
}

public void mouseReleased(MouseEvent event)
{
}
}

class ImageMagnifier extends JFrame
{
ImageIcon temp;

public ImageMagnifier(ImageIcon imageFile,int width,int height,int x,int y)
{
 setUndecorated(true);
 temp=imageFile;
 setLocation(x,y);
 setSize(width*9,height*9);
 setVisible(true);
}

public void paint(Graphics g)
{
 super.paint(g);
 g.drawImage(temp.getImage(),0,0,getSize().width,getSize().height,this);
}
}

********************************************************************
JUST COMPILE AND EXECUTE IT
********************************************************************

Java print pi value

Simple java program below will print pi value in command prompt.

****************************************************************
COMPLETE SOURCE CODE FOR : PrintPiValue.java
****************************************************************

::Click Here To Download This Java Source Code::

public class PrintPiValue
{
public static void main(String[]args)
{
 System.out.println("PI value is : "+Math.PI);
}
}

****************************************************************
JUST COMPILE AND EXECUTE IT
****************************************************************

Java write text file

Program below will ask user to enter their name and some description about them. After that it will write into a text file named MyTextFile.txt with .txt file's extension. You can try with other file format like .doc(Microsoft Word) or .rtf or others that you know to store text file. It's not mean if we write to text file, we must use a file with .txt as it's extension.

Description that i get from Wikipedia about text file is :

A text file (sometimes spelled "textfile": an old alternate name is "flatfile") is a kind of computer file that is structured as a sequence of lines.

So, it's mean a text file can hold any file's extension. Not only for .txt.

*********************************************************************
COMPLETE SOURCE CODE FOR : WriteTextFile.java
*********************************************************************

import java.io.File;
import java.io.PrintWriter;

import java.util.Scanner;

import java.awt.Desktop;

public class WriteTextFile
{
 public static void main(String[]args)
 {
  Scanner scanUserInput=new Scanner(System.in);
  
  File targetedFile=new File("MyTextFile.txt");
  
  System.out.println("What is your name ?");
  String name=scanUserInput.nextLine();
  
  System.out.println("Put some description about yourself");
  System.out.println("-----------------------------------");
  String description=scanUserInput.nextLine();
  
  try
  {
   PrintWriter pw=new PrintWriter(targetedFile);
  
   pw.println("******************");
   pw.println(name + "'s"+" profile");
   pw.println("******************");
   pw.println("Name : "+name);
   pw.println();
   pw.println("Description : "+description);
  
   pw.flush();
   pw.close();
  
  
   Desktop.getDesktop().open(targetedFile);
  }
  catch(Exception exception)
  {
   System.out.println("Problem in file processing");
  }
 }
}

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JUST COMPILE AND EXECUTE IT
*********************************************************************

Java determine prime number

Complete source code below will show you, how to create a simple java program that will determine an input number is a prime number or not. This program will run through command prompt.

********************************************************
COMPLETE SOURCE CODE FOR : JavaDeterminePrimeNumber.java
********************************************************

import java.util.Scanner;

public class JavaDeterminePrimeNumber
{
 public boolean isPrime(int a)
 {
  boolean temp=true;
  if(a==1)
  {
   return false;
  }
  for(int i=2;i<=a;i++)
  {
   if(i!=1&&i!=a)
   {
    int tempResult=a%i;
    if(tempResult==0)
    {
     temp=false;
    }
   }
  }
  return temp;
 }
 
 public static void main(String[]args)
 {
  JavaDeterminePrimeNumber myTest=new JavaDeterminePrimeNumber();
  Scanner s=new Scanner(System.in);
  System.out.println("Enter an int value");
  int response = s.nextInt();
  boolean result=myTest.isPrime(response);
  
  if(result==true)
  {
   System.out.println("This is a prime number");
  }
  else
  {
   System.out.println("This is not a prime number");
  }
 }
}

********************************************************
JUST COMPILE AND EXECUTE IT
********************************************************

Java simple calendar

Complete source code below will show you, how to create simple calendar in java. This program will prompts the user to enter the year and first day of the year, and display the calendar table for the year on the console.

*************************************************************************
COMPLETE SOURCE CODE FOR : JavaSimpleCalendar.java
*************************************************************************

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

public class JavaSimpleCalendar
{
 public static void main(String[]args)
 {
  Scanner s=new Scanner(System.in);
  
  System.out.print("YEAR : ");
  int year=s.nextInt();
  
  System.out.println();
  
  System.out.println("FIRST DAY OF THE YEAR");
  System.out.println("1 for MONDAY");
  System.out.println("2 for TUESDAY");
  System.out.println("3 for WEDNESDAY");
  System.out.println("4 for THURSDAY");
  System.out.println("5 for FRIDAY");
  System.out.println("6 for SATURDAY");
  System.out.println("7 for SUNDAY");
  System.out.print("FIRST DAY : ");
  int firstDay=s.nextInt();
  
  System.out.println();
  
  boolean leapYear=false;
  if(year%4==0)
  {
   leapYear=true;
  }
  
  for(int i=1;i<=12;i++)
  {
   System.out.println("***********************");
   System.out.println("MONTH : "+i);
   System.out.println("***********************");
   
   if(i==1||i==3||i==5||i==7||i==8||i==10||i==12)
   {
    System.out.println("M  T  W  TH F  S  SU");
    boolean firstRound=true;
    for(int j=1;j<=31;j++)
    {
     String temp=Integer.toString(j);
     if(temp.length()==1)
     {
      System.out.print(" ");
     }
     if(firstDay==1)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=1;k++)
       {
        System.out.print("");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==2)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=3;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
      
     }
     else if(firstDay==3)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=6;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==4)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=9;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==5)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=12;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==6)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=15;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==7)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=18;k++)
       {
        System.out.print("-");
       }
       System.out.println(j+" ");
      }
      else
      {
       System.out.println(j+" ");
      }
      firstDay=0;
      firstRound=false;
     }
     firstDay++;
    }
    System.out.println("\n");
   }
   else if(i==2)
   {
    if(leapYear==true)
    {
     System.out.println("M  T  W  TH F  S  SU");
     boolean firstRound=true;
     for(int j=1;j<=29;j++)
     {
      String temp=Integer.toString(j);
      if(temp.length()==1)
      {
       System.out.print(" ");
      }
      if(firstDay==1)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=1;k++)
        {
         System.out.print("");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==2)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=3;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      
      }
      else if(firstDay==3)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=6;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==4)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=9;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==5)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=12;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==6)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=15;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==7)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=18;k++)
        {
         System.out.print("-");
        }
        System.out.println(j+" ");
       }
       else
       {
        System.out.println(j+" ");
       }
       firstDay=0;
       firstRound=false;
      }
      firstDay++;
     }
     System.out.println("\n");
    }
    else
    {
     System.out.println("M  T  W  TH F  S  SU");
     boolean firstRound=true;
     for(int j=1;j<=28;j++)
     {
      String temp=Integer.toString(j);
      if(temp.length()==1)
      {
       System.out.print(" ");
      }
      if(firstDay==1)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=1;k++)
        {
         System.out.print("");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==2)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=3;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      
      }
      else if(firstDay==3)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=6;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==4)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=9;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==5)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=12;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==6)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=15;k++)
        {
         System.out.print("-");
        }
        System.out.print(j+" ");
       }
       else
       {
        System.out.print(j+" ");
       }
      }
      else if(firstDay==7)
      {
       if(firstRound==true&&j==1)
       {
        for(int k=1;k<=18;k++)
        {
         System.out.print("-");
        }
        System.out.println(j+" ");
       }
       else
       {
        System.out.println(j+" ");
       }
       firstDay=0;
       firstRound=false;
      }
      firstDay++;
     }
     System.out.println("\n");
    }
   }
   else
   {
    System.out.println("M  T  W  TH F  S  SU");
    boolean firstRound=true;
    for(int j=1;j<=30;j++)
    {
     String temp=Integer.toString(j);
     if(temp.length()==1)
     {
      System.out.print(" ");
     }
     if(firstDay==1)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=1;k++)
       {
        System.out.print("");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==2)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=3;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
      
     }
     else if(firstDay==3)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=6;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==4)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=9;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==5)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=12;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==6)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=15;k++)
       {
        System.out.print("-");
       }
       System.out.print(j+" ");
      }
      else
      {
       System.out.print(j+" ");
      }
     }
     else if(firstDay==7)
     {
      if(firstRound==true&&j==1)
      {
       for(int k=1;k<=18;k++)
       {
        System.out.print("-");
       }
       System.out.println(j+" ");
      }
      else
      {
       System.out.println(j+" ");
      }
      firstDay=0;
      firstRound=false;
     }
     firstDay++;
    }
    System.out.println("\n");
   }
  }
 }
}

*************************************************************************
JUST COMPILE AND EXECUTE IT
*************************************************************************

Java scale image

Sephiroth_by_Wen_JR.jpg

Complete source code below will show you, how to scale an image in java using AffineTransform class. It will scale base on x and y axis.

************************************************************************
COMPLETE SOURCE CODE FOR : ScaleImage.java
************************************************************************

import java.awt.Image;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Toolkit;
import java.awt.BorderLayout;
import java.awt.Dimension;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import java.awt.geom.AffineTransform;

import javax.swing.JScrollPane;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JButton;
import javax.swing.JTextField;
import javax.swing.JPanel;
import javax.swing.ImageIcon;

public class ScaleImage extends JPanel implements ActionListener
{
 JScrollPane scrollBar;
 JPanel panelB;
 JButton button;
 JTextField textFieldX;
 JTextField textFieldY;
 JFrame myWindow;
 ImageIcon ii;
 
 AffineTransform at=new AffineTransform();
 
 Image myImage;
 
 double x=0.3;
 double y=0.3;
 
 public ScaleImage()
 {
  //CHANGE Sephiroth_by_Wen_JR.jpg TO IMAGE THAT YOU WANT
  myImage=Toolkit.getDefaultToolkit().getImage("Sephiroth_by_Wen_JR.jpg");
    
  ii=new ImageIcon(myImage);
  
  JLabel labelX=new JLabel("X : ");
  JLabel labelY=new JLabel("Y : ");
  textFieldX=new JTextField("0.3",10);
  textFieldY=new JTextField("0.3",10);
  button=new JButton("Refresh");
  
  button.addActionListener(this);
  
  panelB=new JPanel();
  panelB.add(labelX);
  panelB.add(textFieldX);
  panelB.add(labelY);
  panelB.add(textFieldY);
  panelB.add(button);
  
  setPreferredSize(new Dimension((int)(ii.getIconWidth()*x),(int)(ii.getIconHeight()*y)));
  scrollBar=new JScrollPane(this);
  
  myWindow=new JFrame("Scale image");
  myWindow.getContentPane().setLayout(new BorderLayout());  
  myWindow.getContentPane().add(scrollBar,BorderLayout.CENTER);
  myWindow.getContentPane().add(panelB,BorderLayout.SOUTH); 
  myWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  myWindow.setSize(500,500);
  myWindow.setLocationRelativeTo(null);
  myWindow.setVisible(true);
 }
 
 public void actionPerformed(ActionEvent e)
 {
  if(e.getSource()==button)
  {
   x=Double.parseDouble(textFieldX.getText());
   y=Double.parseDouble(textFieldY.getText());
   
   setPreferredSize(new Dimension((int)(ii.getIconWidth()*x),(int)(ii.getIconHeight()*y)));
   
   myWindow.repaint();
   scrollBar.revalidate();
  }
 }
 
 public void paint(Graphics g)
 {
   at.setToScale(x,y);
   Graphics2D g2d=(Graphics2D)g;
   g2d.drawImage(myImage,at,this);
 }
 
 public static void main(String[]args)
 {
  ScaleImage si=new ScaleImage();
 }
}

************************************************************************
JUST COMPILE AND EXECUTE
Note : Make sure Sephiroth_by_Wen_JR.jpg locate at same location with this source file
************************************************************************

Create exception handling

In this post, i want to share with you about how to create our own exception handling. Sometime when we build our program, we want it to handle certain mistake or exception that not exist in java predefined exception class.For example we want to control user from put negative integer value. Complete source code below will show you, how you can create an exception class that avoid user from put negative integer value.

*************************************************************
COMPLETE SOURCE CODE FOR : NegativeIntegerException.java
*************************************************************

import java.util.Scanner;

public class NegativeIntegerException extends RuntimeException
{
 public void checkNumber(int a)
 {
  if(a<0)
  {
   throw new NegativeIntegerException();
  }
 }
 
 public static void main(String[]args)
 {
  Scanner scanUserInput=new Scanner(System.in);
  NegativeIntegerException nie=new NegativeIntegerException();
  boolean b=true;
  while(b)
  {
   System.out.println("Put an integer");
   System.out.println("Put 0 EXIT");
   int c=scanUserInput.nextInt();
   if(c==0)
   {
    b=false;
   }
   else
   {
    try
    {
     nie.checkNumber(c);
     System.out.println("YOUR NUMBER IS : "+c);
    }
    catch(NegativeIntegerException exception)
    {
     System.out.println("<<PLEASE PUT ONLY POSITIVE INTEGER!!!>>");
    }
   }
  }
 }
}

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JUST COMPILE AND EXECUTE IT
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Java exception handling

Now, i want to share with you about exception handling in java. Okay, this is only for introduction to exception handling. Firstly, what is exception?

Exception - a person or thing that is excepted or that does not follow a rule.

So, if we talk about exception handling in java program, it mean we want to handle any mistake that we can handle during compile time or runtime.

For example :
-User put String into input field that only handle integer value.
-Out of memory.
-Array index that over than it's (length-1) or negative value. We also called it as ArrayIndexOutOfBoundsException

Why, i said "we want to handle any mistake that we can handle"?The answer is, there exist error that we can't handle.

For example :
-Blue screen of death(BSOD)
-Computer suddenly crash
-Black out
-Or someone switch off your computer

Ok, i hope you understand what i mean until this line. Why we need exception handling ? The answer is, we want to make sure our program is robust. It will try to handle any mistake that the user make.

Now, we will see two sample java programs. Both of them will ask user to input their age.After that, it will print it's value. This program only terminate when user put 0. Like we know, age is integer value. It can't be floating point number or String except your program need the user to put it in String. It is make not sense if when you ask someone for their age, and after that it answer like this "MY AGE IS 19.28". First program will has no exception handling. It will print some description about exception that occur and after that the program will end without follow program flow when the user put String value or others. But, in second program, it totally different. It will tell user that the input is wrong. After that, it will ask again until user put 0 to exit.Let we see both of them.Before i forget, if you put negative integer value, this program will work fine because it also integer. I will discuss later, about how to handle this in how to create our own exception handling.

FIRST PROGRAM :

import java.util.Scanner;

public class Test
{
 public static void main(String[]args)
 {
  while(true)
  {
   Scanner scanUserInput=new Scanner(System.in);
   System.out.println("Put 0 to exit");
   System.out.println("What is your age ?");
   int a=scanUserInput.nextInt();
   if(a==0)
   {
    System.exit(0);
   }
   System.out.println("YOUR AGE IS : "+a);
  }
 }
}

SECOND PROGRAM :

import java.util.Scanner;
import java.util.InputMismatchException;

public class Test
{
 public static void main(String[]args)
 {
  while(true)
  {
   try
   {
    Scanner scanUserInput=new Scanner(System.in);
    System.out.println("Put 0 to exit");
    System.out.println("What is your age ?");
    int a=scanUserInput.nextInt();
    if(a==0)
    {
     System.exit(0);
    }
    System.out.println("YOUR AGE IS : "+a);
   }
   catch(InputMismatchException exception)
   {
    System.out.println("Hey, don't play with me!");
    System.out.println("PLEASE PUT ONLY INTEGER VALUE");
   }
  }
 }
}

Java modal window

Hi everyone, today i want to share with you about MODAL WINDOW.How it's look like? Before i show you example of MODAL WINDOW, let we look for it's little description :

If a window is modal, no other window can be active while the modal window is displayed.

Simple example is message box from JOptionPane. When a message box is showing, you can't work with other window until you press OK or others button on the message box.
This message box is a simple example of MODAL WINDOW.

You can try compile java code below to see how it's look like.

***********************************************************
COMPLETE SOURCE CODE FOR : ModalWindow.java
***********************************************************

import javax.swing.JFrame;

import javax.swing.JOptionPane;

public class ModalWindow
{
 public static void main(String[]args)
 {
  JFrame myWindow=new JFrame("My Window");
  
  myWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  myWindow.setSize(400,400);
  myWindow.setVisible(true);
  
  JOptionPane.showMessageDialog(null,"Hello");
 }
}

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