Array

- Use to store multiple "elements" together, represented by single variable name
- Need to specify size while declaration, size = total number of elements
- Element can be accessed using array "index"
- Array index starts from zero [0]


======================================================
Ex. 1: Array of int (primitive data type)

Source: TestArray1.java

public class TestArray1 {

    public static void main(String[] args) {
     
        int[ ] ilist = new int [10];
        ilist[0] = 101;
        ilist[7] = 200;
     
        for(int k = 0; k < ilist.length; k++ ) {
            System.out.println(ilist[k]);
        }
    }
}

Output: 
101
0
0
0
0
0
0
200
0
0
======================================================
Ex. 2: Array of float (primitive data type)

Source: TestArray2.java

public class TestArray2 {


    public static void main(String[] args) {
       
        float[] ilist = new float [10]; // size
        ilist[0] = 101.50;
        ilist[7] = 200.25;
       
        for(int k = 0; k < ilist.length; k++ ) {
            System.out.println(ilist[k]);
        }
    }
}

Output: 
101.50
0.0
0.0
0.0
0.0
0.0
0.0
200.25
0.0
0.0
======================================================
Ex. 3: Array of String (reference data type)

Source: TestArray3.java

public class TestArray3 {

   public static void main(String[] args) {
     
   String[] weekdays = new String[7]; // size
        weekdays[0] = "Monday";
        weekdays[1] = "Tuesday";
        weekdays[2] = "Wednesday";
        weekdays[3] = "Thursday";
        weekdays[4] = "Friday";
        weekdays[5] = "Saturday";
        weekdays[6] = "Sunday";
      
        for(int k = 0; k < weekdays.length; k++ ) {
            System.out.println(weekdays[k]);
        }
    }
}

Output: 
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday

Command Line Arguments

With command line arguments it is possible to send configuration information to the application. 

Source: TestArgument.java

public class TestArgument {

         public static void main(String[] args) {        

            int size = Integer.valueOf(args[0]);

            int[] list = new int[size]; 
            System.out.println("Size of the array= " + list.length);           

}

     }

Output: Size of the array=25

Run:

java TestArgument  25

Syntax:

java  ProgramName  argument1  argument2  argumentN