How do I change an applet background color?

By Wayan in Applet, Core API 0 Comment

By default, the applet will usually have a grey background when displayed in a web browser. If you want to change it then you can call the setBackground(java.awt.Color) method and choose the color you want. Defining the background color in the init() method will change the color as soon as the applet initialized.

package org.kodejava.applet;

import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;

public class BackgroundColorApplet extends Applet {
    public void init() {
        // Here we change the default grey color background of an 
        // applet to yellow background.
        setBackground(Color.YELLOW);
    }

    public void paint(Graphics g) {
        g.setColor(Color.BLACK);
        g.drawString("Applet background example", 0, 50);
    }
}

Now we have the applet code ready. To enable the web browser to execute the applet create the following html page.

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Applet Background Color</title>
</head>
<body>
<applet code="org.kodejava.applet.BackgroundColorApplet"
        height="150" width="350">
</applet>
</body>
</html>
** Deprecated: The Applet API is deprecated since JDK 9, no replacement.

How do I replace characters in string?

By Wayan in Core API, Lang Package 0 Comment 
package org.kodejava.lang;

public class StringReplace {
    public static void main(String[] args) {
        String text = "The quick brown fox jumps over the lazy dog";
        System.out.println("Before: " + text);

        // The replace method replace all occurrences of character
        // 'o' with 'u' and returns a new string object.
        text = text.replace('o', 'u');
        System.out.println("After : " + text);
    }
}

The result of the code snippet:

Before: The quick brown fox jumps over the lazy dog
After : The quick bruwn fux jumps uver the lazy dug

How do I copy char array to string?

By Wayan in Core API, Lang Package 0 Comment 
package org.kodejava.lang;

public class CharArrayCopyExample {
    public static void main(String[] args) {
        char[] data = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'};

        // Copy all value in the char array and create a new string out of it.
        String text = String.valueOf(data);
        System.out.println(text);

        // Copy a sub array from the char array and create a new string. The
        // following line will just copy 5 characters starting from array index
        // of 3. If the element copied is outside the array index an
        // IndexOutOfBoundsException will be thrown.
        text = String.copyValueOf(data, 3, 5);
        System.out.println(text);
    }
}

The result:

abcdefghij
defgh

How do I remove leading and trailing white space from string?

By Wayan in Core API, Lang Package 0 Comment 
package org.kodejava.lang;

public class TrimStringExample {
    public static void main(String[] args) {
        String text = "     tattarrattat     ";
        System.out.println("Original      = " + text);
        System.out.println("text.length() = " + text.length());

        // The trim() method will result a new string object with a leading and
        // trailing while space removed.
        text = text.trim();
        System.out.println("Result        = " + text);
        System.out.println("text.length() = " + text.length());
    }
}

The result of the code snippet above:

Original      =      tattarrattat     
text.length() = 22
Result        = tattarrattat
text.length() = 12

How do I format a number with leading zeros?

By Wayan in Core API, Text Package 0 Comment

This example give you an example using java.text.DecimalFormat class to add leading zeros to a number. For another method you can read the see the earlier example on How do I add leading zeros to a number?.

package org.kodejava.text;

import java.text.DecimalFormat;
import java.text.NumberFormat;

public class NumberFormatLeadingZerosExample {
    public static void main(String[] args) {
        NumberFormat formatter = new DecimalFormat("0000000");
        String number = formatter.format(2500);

        System.out.println("Number with leading zeros: " + number);
    }
}

The result of code snippet above:

Number with leading zeros: 0002500