Check out example codes for "Write code to declare an array that will hold calendar months (.e. January to December) java". It will help you in understanding the concepts better.

Code Example 1

public class App {

    public static String months[];

    public static void main ( String[] args ) {

        months = new String[ 13 ];
        months[ 0 ] = null;
        months[ 1 ] = "January";
        months[ 2 ] = "February";
        months[ 3 ] = "March";
        months[ 4 ] = "April";
        months[ 5 ] = "May";
        months[ 6 ] = "June";
        months[ 7 ] = "July";
        months[ 8 ] = "August";
        months[ 9 ] = "September";
        months[ 10 ] = "October";
        months[ 11 ] = "November";
        months[ 12 ] = "December";

        System.out.println ( "DEBUG args: " + Arrays.toString ( args ) );
        if ( args.length == 0 ) {
            System.out.println ( "No month specified. No arguments passed to 'main' method." );
        } else if ( args.length == 1 ) {  // Else we have a single argument as expected.
            int m = Integer.parseInt ( args[ 0 ] );
            System.out.println ( months[ m ] );
        } else if ( args.length > 1 ) {  // Else we have multiple arguments, but expected only one.
            System.out.println ( "ERROR - more than one argument passed to 'main' method." );
        } else {  // Else impossible. Should not reach this point. Defensive programming.
            System.out.println ( "ERROR - Unexpectedly reached IF-ELSE. Should be impossible." );
        }
…

Code Example 2

package array2;

public class Array2 {

    static String months[];
    public static void main(String[] args) {
       months = new String[13];
       months[0] = null ;
       months[1] = "January";
       months[2] = "February";
       months[3] = "March";
       months[4] = "April";
       months[5] = "May";
       months[6] = "June";
       months[7] = "July";
       months[8] = "August";
       months[9] = "September";
       months[10] = "October";
       months[11] = "November";
       months[12] = "December";
       int m = Integer.parseInt( args[0] );
       System.out.println( months[ m ] );
    }
}

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