Array Examples

Arrays

class Array{
    public static void main(String args[]){
        int days[];
        days = new int[12];
        for(int i = 0; i<12;i++){
            days[i] = i;
        }
        for(int i = 0; i<12;i++){
            System.out.println("Day : "+days[i]);
        }
        System.out.println(days.getClass().getName());
    }
}

Alternate Array Declaration

class AlternativeArrayDeclaration{
    public static void main(String args[]){
        /* Array can be declared like : type_name[] variable_name; for eg: public static void main(String[] args) */
        int a1[] = new int[3];
        int[] a2 = new int[2];

        /* We can also declare multiple arrays at a time by this method. */

        int [] a3,a4,a5  = new int [3];
        /* which creates the three array variables of integer type  */
    }
}

Array Assignment

class ArrayAssignment{
    public static void main(String args[]){
        int month[] = {1,2,3,4,5,6,7,8,9,10,11,12};
        for(int i=0;i<12;i++){
            System.out.println("Month : "+month[i]);
        }
    }
}

Average Using Arrays

class Average{
    public static void main(String args[]){
        double marks[] = {40.6,30.5,90.3,20.8,87.5};
        double result=0;

        for(int i=0;i<5;i++){
            result +=marks[i];
        }
        System.out.println("Percentage = "+result/5);
    }
}

Two Dimensional Array

class TwoDimensionalArray{
    public static void main(String args[]){
        int nums[][] = new int[4][5];

        int i,j,k=0;
        for (i=0;i<4;i++){
            for(j=0;j<5;j++){
                nums[i][j] = k;
                k++;
            }
        }

        for (i=0;i<4;i++){
            for(j=0;j<5;j++){
                System.out.print(nums[i][j]+" "); /* Print doesn't gets printed in new line , but println does. Know the difference. */
            }
            System.out.println();
        }
        System.out.println(nums.getClass().getName()); // This returns the class name for corressponding array type.
    }
}

Double Two Dimensional Array

class DoubleTwoDArray{
    public static void main(String args[]){
        double nums[][]= {
                            {0.0,1.0,2.0},
                            {3.0,4.0,5.0},
                            {6.0,7.0,8,0}
                        }; /* Two declare a two dimensional array, the last braces should be ended with braces as like Class in C++ . */
        for(int i=0;i<3;i++){
            for(int j=0;j<3;j++){
                System.out.print(nums[i][j]+ " ");
            }
            System.out.println();
        }
    }
}

Two Dimensional Array Manual Allocation

class TwoDArray{
    public static void main(String args[]){
        int nums[][] = new int[4][];
        nums[0] = new int[1];
        nums[1] = new int[2];
        nums[2] = new int[3];
        nums[3] = new int[4];
        int k = 0;

        for(int i=0;i<4;i++){
            for(int j=0;i<i+1;j++){                
                nums[i][j]=k;
                k++;
            }
        }

        for(int i=0;i<4;i++){
            for(int j=0;i<i+1;j++){
                System.out.print(nums[i][j] + " ");
            }
            System.out.println();
        }
    }
}

Three Dimensional Array

class ThreeDimensionalArray{
    public static void main(String args[]){
        int nums[][][] = new int [3][3][3];
        int l = 0;
        for(int i=0;i<3;i++){
            for(int j=0;j<3;j++){
                for(int k=0;k<3;k++){
                    nums[i][j][k] = l;
                    l++;                    
                }
            }
        }

        for(int i=0;i<3;i++){
            for(int j=0;j<3;j++){
                for(int k=0;k<3;k++){
                    System.out.print(nums[i][j][k]+" ");            
                }
                System.out.println();
            }
            System.out.println("\n");
        }
    }
}