Arrays in Java, What is Array in Java, Declare Arrays, Java Array built-in methods, advantages of Java Arrays, and Drawbacks of Java Arrays.
Java Arrays
• In Java, Array is an Object that holds a fixed number of values of a single data type
• The length of the Array is established when the Array is created.
• Array length is fixed and index starts from zero to n-1,
Declaration of Arrays
1st Method:
Syntax:
dataType arrayName[]; Declare an Array/ Create an Array
arrayName = new dataType[size]; //Define size
arrayName[index] = value; //Assign a value
.
.
.
Example 1:
int a[];
a=new int[3];
a[0] = 10;
a[1] = 20;
a[2] = 30;System.out.println(a[1] + a[2]);//50
Example 2:
Assign values to Array elements that more than the length of Array (Run-time Error).
int a[];
a=new int[3];
a[0] = 10;
a[1] = 20;
a[2] = 30;
a[10] =40;System.out.println(a[1] + a[2]);//50
Example 3:
Assign values to some Array Elements only
int a[];
a=new int[3];
a[0] = 10;
a[1] = 20;System.out.println(a[0] + a[1]);//30
Example 4:
Assign different type of data to Array Elements (Syntax Error)
int a[];
a=new int[3];
a[0] = 10;
a[1] = 20;
//a[2] =10.23;System.out.println(a[0] + a[1]);//30
2nd Method
Syntax:
dataType [] arrayName = new dataType [size]; //Create an Array with length
arrayName[index] = value; //Assign value
.
.
Example:
int [] a = new int [3];
a[0] =10;
a[1] =20;
a[2] =30;
System.out.println(a[1] + a[2]);//50
3rd Method
Syntax:
dataType [] arrayName = {value1, value2, value3, value4};//Create an Array with Initialization
Example:
int [] a= {10, 20, 30, 40};
System.out.println(a[1] +a[3]);//60
Creating different type Arrays
int [] a= {10, 20, 30, 40, 50}; //Array of Integers
char [] b= {‘A’, ‘S’, ‘1’, ‘*’};//Array of Characters
String [] c = {“UFT”, “Selenium”, “RFT”, “SilkTest”};//Array of Strings
double [] d ={1.234, 3.456, 6.45, 7.890}; // Array of decimal point values
boolean [] e = {true, true, false, true, false}; //Array of Boolean Values / Logical Values
System.out.println(a[2]);//30
System.out.println(d[3]);//7.890
System.out.println(e[0]);//true
Two-Dimensional Array
data_type [] [] array_name = new data_type[row_size][column_size];
int[][] myarray = new int[2][2];
myarray[0][0] = 1;
myarray[0][1] = myarray[1][0] = 0;
myarray[1][1] = 1;
Operations on Arrays
1. Find an Array length.
Example:
int [] a= {10, 20, 30, 40, 50};
System.out.println(a.length);//5
2. Copy an Array to a String
int [] a= {10, 20, 30, 40, 50};
String str= Arrays.toString(a);
System.out.println(str);String [] a = {“UFT”, “Selenium”, “RFT”, “SilkTest”};
String str = Arrays.toString(a);
System.out.println(str);
3. Print an Array using for loop
public static void main(String[] args) {
String [] a = {“UFT”, “Selenium”, “RFT”, “SilkTest”, “LoadRunner”};for (int i=0; i<=a.length-1; i++){
System.out.println(a[i]);
4. Print an Array using enhanced for loop
String [] a = {“UFT”, “Selenium”, “RFT”, “SilkTest”, “LoadRunner”};
for (String val: a){
System.out.println(val);
}
5. Check if an Array contains a certain value or not?
String [] a = {“UFT”, “Selenium”, “RFT”, “SilkTest”, “LoadRunner”};
boolean val = Arrays.asList(a).contains(“UFT”);
boolean val2 = Arrays.asList(a).contains(“Java”);
System.out.println(val);//true
System.out.println(val2);//false