Example 1: Declaring & Instantiating an integer array

int[] n = new int[3];      //instantiates an array of 3 integers 

                           //allocates memory for 3 integers

n[0] = 10;                 //assigns first element at index 0 with value 10

n[1] = 20;                 //assigns second element at index 1 with value 20

n[2] = 30;                 //assigns third element at index 2 with value 30

System.out.print(n[0] + " " + n[1] + " " + n[2]);  //prints element of the array 

                                                   //n at specified index location

Output:

10 20 30

Example 2: Declaring, initializing and instantiating an integer array

int[] n = {10,20,30};           //declares and instantiates n array of 3 integers

System.out.print(n[0] + " " + n[1] + " " + n[2]);      //prints element of the 

                                                       //array numbers at index location

Output:

10 20 30

Example 3: Using FOR Loop to assign array indexes as elements of integer array

int[] scores = new int[4];    

for(int i = 0; i < scores.length; i++){        

    scores[i] = i;                           //assigns value i to every index of the array 

}

for(int i = 0; i < scores.length; i++){               

    System.out.print(scores[i] + " ");       //prints every element in the array 

                                             //from index 0 to scores.length  - 1

}

Output:

0 1 2 3

Example 4: Assigning random numbers to array indexes using FOR loop

Random r = new Random();                   //instantiates a Random Object

int[] n = new int[5];                      //instantiates an array of 5 integers

for(int i = 0; i < n.length; i++){                    

    n[i] = r.nextInt(10-1+1) + 1;          //generates random numbers and assigns         

                                           //numbers at index i. 

}

for(int i = 0; i < n.length; i++){         //for loop to access all indexes of the array

    System.out.println(n[i] + " ");        //prints each element in the array 

                                           //from index 0 to scores.length -1

}

Output:(Random numbers from 1 to 10 inclusive)

6 9 6 2 5                                  //array of 5 random integers printed

Example 5: Assigning values to array indexes from user input using FOR loop and Scanner class

double[] grades = new double[5];                      //instantiates an array of 5 doubles

for(int i = 0; i < grades.length; i++){               

    System.out.print("Enter grade: " + (i+1 + " "));  //prompts user to enter grade

    double g = input.nextDouble();                    

    grades[i] = g;                                    //assigns grade g entered at index i

}  

for(double grade: grades){                    //uses enhanced for loop

    System.out.println(grade);                //prints every grade in array grades

}

Output:

Enter grade 1: 67                   //prompts user to enter first grade, user enters 67

Enter grade 2: 78                   //prompts user to enter second grade, user enters 78...

Enter grade 3: 89                   . . .

Enter grade 4: 90                   . . .

Enter grade 5: 78                   . . .

67.0 78.0 89.0 90.0 78.0            //array of grades (double) printed

Example 6: (continuation from Example 5)

finds the highest grade in the array of grades shown in example 5

double highestGrade = 0.0;                       //initializes a starting highest grade

for(int i = 0; i < grades.length; i++){          

    if(grades[i] > highestGrade){                //compares current highestGrade to all grades

        highestGrade = grades[i];                //assigns new highest grade if grade in array 

                                                 //is higher than the highestGrade

    }

}

System.out.println("The highest grade is:" + highestGrade); //prints the highest grade 

Output:

90.0                                             //highest grade is printed