How do I shuffle elements of an array?

By I Wayan Saryada in Core API, Util Package 0 Comment 
package org.kodejava.util;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class ArrayShuffle {
    public static void main(String[] args) {
        // Initialize the contents of our array
        String[] alphabets = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J"};

        // As the Collections.shuffle() method need a list for the parameter
        // we convert our array into List using the Arrays class.
        List<String> list = Arrays.asList(alphabets);

        // Here we just simply used the shuffle method of Collections class
        // to shuffle out defined array.
        Collections.shuffle(list);

        // Run the code again and again, then you'll see how simple we do
        // shuffling
        for (String alpha : list) {
            System.out.print(alpha + " ");
        }
    }
}

An example of the generated results are:

F H E A B I G J D C

How do I use for-each in Java?

By I Wayan Saryada in Core API, Lang Package 0 Comment

Using for-each command to iterate arrays or a list can simplified our code. Below is an example how to do it in Java. The first loop is for iterating array and the second for iterating a list containing a some names.

package org.kodejava.lang;

import java.util.ArrayList;
import java.util.List;

public class ForEachExample {
    public static void main(String[] args) {
        Integer[] numbers = {10, 100, 1000, 10000, 100000, 1000000};

        for (Integer i : numbers) {
            System.out.println("Number: " + i);
        }

        List<String> names = new ArrayList<>();
        names.add("Musk");
        names.add("Nakamoto");
        names.add("Einstein");

        for (String name : names) {
            System.out.println("Name: " + name);
        }
    }
}

The result of the code snippet:

Number: 10
Number: 100
Number: 1000
Number: 10000
Number: 100000
Number: 1000000
Name: Musk
Name: Nakamoto
Name: Einstein

How do I convert string to an integer or number?

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

public class StringToInteger {
    public static void main(String[] args) {
        // Some random selected number, could representing a decimal,
        // hexadecimal or octal number.
        String myLuckyNumber = "13";

        // We convert a string to an integer by invoking parseInt() method
        // of the Integer class.
        int number = Integer.parseInt(myLuckyNumber);
        System.out.println("My lucky number is: " + number);

        // We can also converting a string representation of a number other
        // then the decimal base, for instance an hexadecimal by providing
        // the radix to the method.
        number = Integer.parseInt(myLuckyNumber, 16);
        System.out.println("My lucky number is: " + number);

        number = Integer.parseInt(myLuckyNumber, 8);
        System.out.println("My lucky number is: " + number);
    }
}

Our code results are:

My lucky number is: 13
My lucky number is: 19
My lucky number is: 11

How do I know the minimum and maximum number in an array?

By I Wayan Saryada in Core API, Util Package 0 Comment 
package org.kodejava.util;

import java.util.Arrays;
import java.util.Collections;

public class ArrayMinMax {
    public static void main(String[] args) {
        // Creates an array of integer numbers in it.
        Integer[] numbers = {8, 2, 6, 7, 0, 1, 4, 9, 5, 3};

        // To get the minimum or maximum value from the array we can
        // use the Collections.min() and Collections.max() methods.
        // But as this method requires a list type of data we need
        // to convert the array to list first.
        int min = Collections.min(Arrays.asList(numbers));
        int max = Collections.max(Arrays.asList(numbers));

        // Viola! we get the minimum and the maximum value from the
        // array.
        System.out.println("Min number: " + min);
        System.out.println("Max number: " + max);
    }
}

And here are the results:

Min number: 0
Max number: 9

How can I change file attribute to writable?

By I Wayan Saryada in Core API, IO 0 Comment

Prior to Java 1.6 the java.io.File class doesn’t include a method to change a read only file attribute and make it writable. To do this on the old days we have to utilize or called operating system specific command. In Java 1.6 a new method named setWritable() was introduced to do exactly what the method name says.

package org.kodejava.io;

import java.io.File;

public class WritableExample {
    public static void main(String[] args) throws Exception {
        File file = new File("Writable.txt");

        // Create a file only if it doesn't exist.
        boolean created = file.createNewFile();

        // Set file attribute to read only so that it cannot be written
        boolean succeeded = file.setReadOnly();

        // We are using the canWrite() method to check whether we can
        // modified file content.
        if (file.canWrite()) {
            System.out.println("File is writable!");
        } else {
            System.out.println("File is in read only mode!");
        }

        // Now make our file writable
        succeeded = file.setWritable(true);

        // re-check the read-write status of file
        if (file.canWrite()) {
            System.out.println("File is writable!");
        } else {
            System.out.println("File is in read only mode!");
        }
    }
}

And here are the result of the code snippet above:

File is in read only mode!
File is writable!