How do I use for-each in Java?

By Wayan 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 know the minimum and maximum number in an array?

By Wayan 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 do I convert string to char array?

By Wayan in Core API, Lang Package 0 Comment

Here we have a small class that convert a string literal into an array, a character array. To do this we can simply use String.toCharArray() method.

package org.kodejava.lang;

public class StringToArrayExample {
    public static void main(String[] args) {
        // We have a string literal that contains the tag line of this blog.
        String literal = "Kode Java - Learn Java by Examples";

        // Now we want to convert or divided it into a small array of char.
        // To do this we can simply used String.toCharArray() method. This
        // method splits the string into an array of characters.
        char[] temp = literal.toCharArray();

        // Here we just iterate the char array and print it to our console.
        for (char c : temp) {
            System.out.print(c);
        }
    }
}

How do I convert Array to Collection?

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

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

public class ArrayToListExample {
    public static void main(String[] args) {
        // Creates an array of object, in this case we create an
        // Integer array.
        Integer[] numbers = {1, 1, 2, 3, 5, 8, 13, 21, 34, 55};

        // Convert the created array above to collection, in this
        // example we convert it to a List.
        List<Integer> list = Arrays.asList(numbers);

        // We've got a list of our array here and iterate it.
        for (Integer number : list) {
            System.out.print(number + ", ");
        }
    }
}

How do I split a string?

By Wayan in Core API, Lang Package 0 Comment

Prior to Java 1.4 we use java.util.StringTokenizer class to split a tokenized string, for example a comma separated string. Starting from Java 1.4 and later the java.lang.String class introduce a String.split(String regex) method that simplify this process.

Below is a code snippet how to do it.

package org.kodejava.lang;

import java.util.Arrays;

public class StringSplit {
    public static void main(String[] args) {
        String data = "1,Diego Maradona,Footballer,Argentina";
        String[] items = data.split(",");

        // Iterates the array to print it out.
        for (String item : items) {
            System.out.println("item = " + item);
        }

        // Or simply use Arrays.toString() when print it out.
        System.out.println("item = " + Arrays.toString(items));
    }
}

The result of the code snippet:

item = 1
item = Diego Maradona
item = Footballer
item = Argentina
item = [1, Diego Maradona, Footballer, Argentina]