Java

trying to learn java in 3 or 4 months

19-Jan-14 5:19

Probably by writing some code, but without some detailed information of the problem it is impossible to suggest more. BTW please leave your questions at the default font size.

Veni, vidi, abiit domum

Re: servlets

Marco Bertschi20-Jan-14 20:02

Marco Bertschi

20-Jan-14 20:02

I am sure you wanted to enter that somewhere else[^]

Veni, vidi, caecus | Everything summarizes to Assembly code

Re: servlets

Manfred Rudolf Bihy20-Jan-14 20:43

Manfred Rudolf Bihy

20-Jan-14 20:43

I've used both JFreeChart[^] and Jasper Reports. The former had issues though in that it was not thread safe. The latter is no longer freely available it seems. I just did a quick search and it now seems to be a commercial product, which is really a shame as it was really a great tool when I tried it 2006 - 2007.

Cheers!

"I had the right to remain silent, but I didn't have the ability!"

Ron White, Comedian

shchandhu17-Jan-14 7:37

shchandhu

17-Jan-14 7:37

i've basic knowledge about programming
now i have to learn java in 3 months or 4 months if needed
have to do java certification
i've all my day dedicated to this
need valuable advices

i know one can learn programming best by doing.. so going to do that
i may do things that waste time like concentrating on insignificant things... i hope you guys will guide me correctly as i will post what i've learned and practiced daily

if there is any blog or thread like this.. plz refer it to me..

suggest me valuable resources to start with like thinking in java

Re: trying to learn java in 3 or 4 months

shchandhu17-Jan-14 7:54

shchandhu

17-Jan-14 7:54

found a valuable one
http://www.daniweb.com/software-development/java/threads/99132/starting-java-java-tutorials-resources-faq

C to Java translation

Kujtim Hyseni13-Jan-14 5:03

13-Jan-14 5:03

Hi,

is there a reliable tool which can convert completely a C code to Java. C code contains only bit operations such AND, OR ... XOR, addition, subtraction and like and is not dependent on particular library. The tool should convert the code completely i.e. without my intervention after translation.

Richard MacCutchan13-Jan-14 5:23

13-Jan-14 5:23

Kujtim Hyseni wrote:
The tool should convert the code completely i.e. without my intervention after translation.

It is unlikely that any tool is capable of doing that since there are enough subtle differences in the languages, and coding style to confuse it. If you want a selection of tools that you can try for yourself then Google is your friend.

Veni, vidi, abiit domum

Kujtim Hyseni13-Jan-14 6:08

13-Jan-14 6:08

When I translate the C code to C# it works fine because in both C and C# there is unsigned 8 bit integer type "byte" (values from 0 to 255) while in Java "byte" is signed 8 bit integer (values from -128 to 127). What operations might have effect when signed used instead of unsigned?

Richard MacCutchan13-Jan-14 7:18

13-Jan-14 7:18

If you use arithmetic operations on them then you will get incorrect results.

Veni, vidi, abiit domum

Kujtim Hyseni13-Jan-14 7:24

13-Jan-14 7:24

How do you mean, can you explain me more ?

Richard MacCutchan13-Jan-14 7:39

13-Jan-14 7:39

Try this code:

Java

public static void main(String[] args) throws Exception {
    byte b1 = (byte)129;
    byte b2 = 4;
    byte b3 = (byte)(b1 + b2);
    System.out.println("b1 is: " + b1);
    System.out.println("b2 is: " + b2);
    System.out.println("b3 is: " + b3);

If the byte values were unsigned you would expect the answer to be 133, but in fact you will get -123, since the 'real' value of b1 is, as you see, -127.

Veni, vidi, abiit domum

Kujtim Hyseni13-Jan-14 7:41

13-Jan-14 7:41

Yes, but I am receiving un-correlated values, how to get 133 instead of -123 - I mean what modifications or things I have to do at the end?

Richard MacCutchan13-Jan-14 23:14

13-Jan-14 23:14

You have to get the value as an integer and then mask off the low order 8 bits, to make it into an unsigned value, like this:

Java

public static void main(String[] args) throws Exception {
    byte b1 = (byte)129;   // b1 is the original unsigned value, which takes the full 8 bits
    byte b2 = 4;           // b2 is a normal value
    int i1 = b1;           // make b1 an integer
    int i2 = i1 & 0xFF;    // mask off all but the low order 8 bits, i.e. the original byte value
    int i3 = i2 + b2;      // add the two original values together
    System.out.println("i1 is: " + i1);  // the negative byte value, same as b1
    System.out.println("i2 is: " + i2);  // the unsigned value
    System.out.println("i3 is: " + i3);  // the sum of the two numbers
}

[edit]Fixed typo; I meant low order 8 bits.[/edit]

Veni, vidi, abiit domum

modified 14-Jan-14 11:02am.

thatraja13-Jan-14 6:43

thatraja

13-Jan-14 6:43

You can't expect 100% automatic conversion. Even commercial products offers only 95-99% conversion.
In Google you could find few free converters. Ex. C To Java Converter[^]

There's a better way if you have more time & resources. Code Rewrite[^]

thatraja

Code converters | Education Needed
No thanks, I am all stocked up. - Luc Pattyn
When you're wrestling a gorilla, you don't stop when you're tired, you stop when the gorilla is - Henry Minute

Resize objects from an ArrayList

jschell13-Jan-14 9:25

jschell

13-Jan-14 9:25

I wouldn't think that would work at all for any non-trivial business application.

And once translated it would be so mucked up that it would be significantly more costly to maintain.

ririsuperstar11-Jan-14 4:44

ririsuperstar

11-Jan-14 4:44

Ok, here is the code to resize one rectangle.
I would like to display several rectangles and resize them independantly, so the best way is to create an arraylist, right ? I have modified the code (see at the bottom), but it displays only the rectangles. No error messages when I test the program, but impossible to resize them.

Java

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Resizing extends JPanel {
    Rectangle rect = new Rectangle(100,100,150,150);

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.blue);
        g2.draw(rect);
    }

    public static void main(String[] args) {
        Resizing test = new Resizing();
        Resizer resizer = new Resizer(test);
        test.addMouseListener(resizer);
        test.addMouseMotionListener(resizer);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(test);
        f.setSize(400,400);
        f.setLocation(100,100);
        f.setVisible(true);
    }
}

/**
* MouseAdapter okay for j2se 1.6+
* Use MouseInputAdapter for j2se 1.5-
*/
class Resizer extends MouseAdapter {
    Resizing component;
    boolean dragging = false;
    // Give user some leeway for selections.
    final int PROX_DIST = 3;

    public Resizer(Resizing r) {
        component = r;
    }

    public void mousePressed(MouseEvent e) {
        if(component.getCursor() != Cursor.getDefaultCursor()) {
            // If cursor is set for resizing, allow dragging.
            dragging = true;
        }
    }

    public void mouseReleased(MouseEvent e) {
        dragging = false;
    }

    public void mouseDragged(MouseEvent e) {
        if(dragging) {
            Point p = e.getPoint();
            Rectangle r = component.rect;
            int type = component.getCursor().getType();
            int dx = p.x - r.x;
            int dy = p.y - r.y;
            switch(type) {
                case Cursor.N_RESIZE_CURSOR:
                    int height = r.height - dy;
                    r.setRect(r.x, r.y+dy, r.width, height);
                    break;
                case Cursor.S_RESIZE_CURSOR:
                    height = dy;
                    r.setRect(r.x, r.y, r.width, height);
                    break;
                default:
                    System.out.println("unexpected type: " + type);
            }
            component.repaint();
        }
    }

    public void mouseMoved(MouseEvent e) {
        Point p = e.getPoint();
        if(!isOverRect(p)) {
            if(component.getCursor() != Cursor.getDefaultCursor()) {
                // If cursor is not over rect reset it to the default.
                component.setCursor(Cursor.getDefaultCursor());
            }
            return;
        }
        // Locate cursor relative to center of rect.
        int outcode = getOutcode(p);
        Rectangle r = component.rect;
        switch(outcode) {
            case Rectangle.OUT_TOP:
                if(Math.abs(p.y - r.y) < PROX_DIST) {
                    component.setCursor(Cursor.getPredefinedCursor(
                                        Cursor.N_RESIZE_CURSOR));
                }
                break;
            case Rectangle.OUT_BOTTOM:
                if(Math.abs(p.y - (r.y+r.height)) < PROX_DIST) {
                    component.setCursor(Cursor.getPredefinedCursor(
                                        Cursor.S_RESIZE_CURSOR));
                }
                break;
            default:    // center
                component.setCursor(Cursor.getDefaultCursor());
        }
    }

    /**
     * Make a smaller Rectangle and use it to locate the
     * cursor relative to the Rectangle center.
     */
    private int getOutcode(Point p) {
        Rectangle r = (Rectangle)component.rect.clone();
        r.grow(-PROX_DIST, -PROX_DIST);
        return r.outcode(p.x, p.y);
    }

    /**
     * Make a larger Rectangle and check to see if the
     * cursor is over it.
     */
    private boolean isOverRect(Point p) {
        Rectangle r = (Rectangle)component.rect.clone();
        r.grow(PROX_DIST, PROX_DIST);
        return r.contains(p);
    }
}

MODIFIED CODE

Java

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Path2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import javax.swing.*;

class Resizing extends JPanel {

    ArrayList paths = new ArrayList();


        public Resizing() {
            paths.add(wrap(new Rectangle2D.Double(100, 100, 75, 50)));
            paths.add(wrap(new Rectangle2D.Double(250, 100, 75, 50)));

        }

        private Path2D.Double wrap(Shape s) {
            return new Path2D.Double(s);
        }

    <a href="/Members/override">@Override</a>
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
            Graphics2D g2 = (Graphics2D)g;
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                                RenderingHints.VALUE_ANTIALIAS_ON);
            g2.setPaint(Color.blue);
            for(int j = 0; j < paths.size(); j++) {
                Path2D.Double path = (Path2D.Double)paths.get(j);
                g2.draw(path);
            }
        }


    public static void main(String[] args) {
            JFrame f = new JFrame();
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.add(new Resizing());
            f.setSize(400,400);
            f.setLocation(100,100);
            f.setVisible(true);

    }

class Resizer extends MouseAdapter {
    Resizing component;
    boolean dragging = false;
    // Give user some leeway for selections.
    final int PROX_DIST = 3;
    Path2D.Double selectedPath;

    public Resizer(Resizing rz) {
        component = rz;
        component.addMouseListener(this);
        component.addMouseMotionListener(this);
    }

    public void mousePressed(MouseEvent e) {
        if(component.getCursor() != Cursor.getDefaultCursor()) {
            // If cursor is set for resizing, allow dragging.
            dragging = true;
        }
    }

    public void mouseReleased(MouseEvent e) {
        dragging = false;
    }

    public void mouseDragged(MouseEvent e) {
        if(dragging) {
            Point p = e.getPoint();
            ArrayList list = component.paths;
            for(int j = 0; j < list.size(); j++) {
                Path2D.Double path = (Path2D.Double)list.get(j);
                selectedPath = path;
                Rectangle r = selectedPath.getBounds();
                int type = component.getCursor().getType();
                int dx = p.x - r.x;
                int dy = p.y - r.y;
                switch(type) {
                case Cursor.N_RESIZE_CURSOR:
                    int height = r.height - dy;
                    r.setRect(r.x, r.y+dy, r.width, height);
                    break;
                case Cursor.S_RESIZE_CURSOR:
                    height = dy;
                    r.setRect(r.x, r.y, r.width, height);
                    break;
                default:
                    System.out.println("unexpected type: " + type);
                }
                component.repaint();
            }}
    }

    public void mouseMoved(MouseEvent e) {
        Point p = e.getPoint();
        if(!isOverRect(p)) {
            if(component.getCursor() != Cursor.getDefaultCursor()) {
                // If cursor is not over rect reset it to the default.
                component.setCursor(Cursor.getDefaultCursor());
            }
            return;
        }
        // Locate cursor relative to center of rect.
        int outcode = getOutcode(p);
        ArrayList list = component.paths;
        Rectangle r = selectedPath.getBounds();
        switch(outcode) {
            case Rectangle.OUT_TOP:
                if(Math.abs(p.y - r.y) < PROX_DIST) {
                    component.setCursor(Cursor.getPredefinedCursor(
                                        Cursor.N_RESIZE_CURSOR));
                }
                break;
            case Rectangle.OUT_BOTTOM:
                if(Math.abs(p.y - (r.y+r.height)) < PROX_DIST) {
                    component.setCursor(Cursor.getPredefinedCursor(
                                        Cursor.S_RESIZE_CURSOR));
                }
                break;
            default:    // center
                component.setCursor(Cursor.getDefaultCursor());
        }}

    /**
     * Make a smaller Rectangle and use it to locate the
     * cursor relative to the Rectangle center.
     */
    private int getOutcode(Point p) {
        Rectangle r = (Rectangle)component.paths.clone();
        r.grow(-PROX_DIST, -PROX_DIST);
        return r.outcode(p.x, p.y);
    }

    /**
     * Make a larger Rectangle and check to see if the
     * cursor is over it.
     */
    private boolean isOverRect(Point p) {
        Rectangle r = (Rectangle)component.paths.clone();
        r.grow(PROX_DIST, PROX_DIST);
        return r.contains(p);
    }
}}

java technology

Member 1051702110-Jan-14 16:25

Member 10517021

10-Jan-14 16:25

i am making an educational application using java technology.
where i need to send password on user's mobile in forgot password condition.
would you plz send me its code?

Re: java technology

Richard Andrew x6410-Jan-14 16:44

Richard Andrew x64

10-Jan-14 16:44

Here you go: Teh codez[^]

The difficult we do right away...
...the impossible takes slightly longer.

Re: java technology

Richard MacCutchan10-Jan-14 22:11

10-Jan-14 22:11

Veni, vidi, abiit domum

Re: java technology

Richard MacCutchan10-Jan-14 22:11

Would like to retrieve RGB pixel values from another method but couldn't retrieve it

10-Jan-14 22:11

Please read http://www.codeproject.com/Messages/3137511/Forum-Guidelines-PLEASE-READ.aspx[^].

Veni, vidi, abiit domum

nurul azila9-Jan-14 5:02

nurul azila

9-Jan-14 5:02

I'm still new to Java. I'm having trouble while retrieving the RGB pixel values from my method, compareHexaRGB which in this method I could get the difference pixel values based on comparison of 2 similar images. I tried the printString2DArray method but it doesn't work. It stated either incompatible types: String[][] cannot be converted to String[] or produce errors such as [[Ljava.lang.String;@6d09a8df

After I get the values, I would like to combine it to one Hex value then convert it to ASCII characters. I couldn't proceed to this process as the retrieve value couldn't work.

Here is the code for compareHexaRGB() method:

public class compareHexaRGB
 {
  private static int w;
  private static int h;
  private static BufferedImage img;
  private static BufferedImage img2;
  private static String[][] check_hex2;
  private static String[][] check_hex4;
  private static String[][] message;

  public static void compareHexaRGB(BufferedImage image, BufferedImage image2, int width, int height) throws IOException
 {
 w = width;
 h = height;
 img = image;
 img2 = image2;

 }

 public void check() throws IOException
 {
     getPixelRGB1 pixel = new getPixelRGB1();
     getPixelData1 newPD = new getPixelData1();

     int[] rgb;
     int count = 0;

     int[][] pixelData = new int[w * h][3];
     check_hex2 = new String[w][h];
     check_hex4 = new String[w][h];

     for(int i = 0; i < w; i++)
     {
         for(int j = 0; j < h; j++)
         {
             rgb = newPD.getPixelData(img, i, j);

             for(int k = 0; k < rgb.length; k++)
             {
                 pixelData[count][k] = rgb[k];
             }

                 if(pixel.display_imgHex2()[i][j].equals(pixel.display_img2Hex2()[i][j]))
                 {
                     System.out.println("\nPixel values at position 2 are the same." + "\n" + pixel.display_imgHex2()[i][j] + "  " + pixel.display_img2Hex2()[i][j]);
                 }
                 if(pixel.display_imgHex4()[i][j].equals(pixel.display_img2Hex4()[i][j]))
                 {
                     System.out.println("\nPixel values at position 4 are the same." + "\n" + pixel.display_imgHex4()[i][j] + "  " + pixel.display_img2Hex4()[i][j]);
                 }
                 if(!pixel.display_imgHex2()[i][j].equals(pixel.display_img2Hex2()[i][j]))
                 {
                     System.out.println("\nPixel values at position 2 are not the same." + "\n" + pixel.display_imgHex2()[i][j] + "  " + pixel.display_img2Hex2()[i][j]);
                     check_hex2[i][j] = pixel.display_img2Hex2()[i][j];
                     System.out.println("\nOutput Hex 2: " + check_hex2[i][j]);
                 }
                 if(!pixel.display_imgHex4()[i][j].equals(pixel.display_img2Hex4()[i][j]))
                 {
                     System.out.println("\nPixel values at position 4 are not the same." + "\n" + pixel.display_imgHex4()[i][j] + "  " + pixel.display_img2Hex4()[i][j]);
                     check_hex4[i][j] = pixel.display_img2Hex4()[i][j];
                     System.out.println("\nOutput Hex 4: " + check_hex4[i][j]);
                 }
                 if(!pixel.display_imgHex2()[i][j].equals(pixel.display_img2Hex2()[i][j]) || (!pixel.display_imgHex4()[i][j].equals(pixel.display_img2Hex4()[i][j])))
                 {
                     System.out.println("\nOne of the pixel values at position 2 and 4 are not the same." + "\n" + pixel.display_imgHex2()[i][j] + "  " + pixel.display_img2Hex2()[i][j] + "\n" + pixel.display_imgHex4()[i][j] + "  " + pixel.display_img2Hex4()[i][j]);

                     if(!pixel.display_imgHex2()[i][j].equals(pixel.display_img2Hex2()[i][j]) || (pixel.display_imgHex2()[i][j].equals(pixel.display_img2Hex2()[i][j])))
                     {
                         check_hex2[i][j] = pixel.display_img2Hex2()[i][j];
                         System.out.println("\nOutput Hex 2: " + check_hex2[i][j]);
                     }

                     if(!pixel.display_imgHex4()[i][j].equals(pixel.display_img2Hex4()[i][j]) || (pixel.display_imgHex4()[i][j].equals(pixel.display_img2Hex4()[i][j])))
                     {
                         check_hex4[i][j] = pixel.display_img2Hex4()[i][j];
                         System.out.println("\nOutput Hex 4: " + check_hex4[i][j]);
                     }

                 }
             count++;
             System.out.println("\nOutput Count: " + count);
         }

     }

 }

 public String[][] getCheck_hex2()
 {
     return check_hex2;
 }

 public String[][] getCheck_hex4()
 {
     return check_hex4;
 }
 }

Code for extractMessage() method:

public class extractMessage
{
private static String character;
private static String[][] char1;
private static String[][] char2;
private static int w;
private static int h;

private static void printString2DArray(String[][] in)
{
    for (int i = 0; i < in.length; i++)
    {
        if (i != 0)
        {
            System.out.print(", ");
        }
        System.out.print(java.util.Arrays.toString(in[i]));
    }
}

public static void charExtract()
{
compareHexaRGB hexRGB = new compareHexaRGB();

char1 = new String[][]
{
new String[] { hexRGB.getCheck_hex2() } //error stated incompatible types
};

System.out.println("Char 1: ");
printString2DArray(hexRGB.getCheck_hex2());

}

public String convertHexToString()
{
StringBuilder sb = new StringBuilder();
StringBuilder temp = new StringBuilder();

extractMessage extract = new extractMessage();
extract.charExtract();

for(int i = 0; i < extract.length(); i+=2) //error stated couldn't find symbol extract
{
String output = extract.substring(i, (i + 2));
int decimal = Integer.parseInt(output, 16);
sb.append((char)decimal);

temp.append(decimal);
}
return sb.toString();
}
}

Any help I would appreciate!

modified 9-Jan-14 11:23am.

Re: Would like to retrieve RGB pixel values from another method but couldn't retrieve it

Richard MacCutchan9-Jan-14 21:17