Java Programming- Arrays & Control Statements

Array

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• Arrays are used to store multiple values in a single variable, instead of declaring separate variables for each value.

Types of Array in java

There are two types of array.

• Single Dimensional Array
• Multidimensional Array

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Single Dimensional Array in Java

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Syntax to Assign value to an Array

1. dataType arr[ ] = { val1,val2..};

Syntax to Declare an Array

1. dataType[ ] arr; (or)
2. dataType arr[ ];

Example

int myNum[ ] = {10, 20, 30, 40};

String cars[ ] = {"Volvo", "BMW", "Ford", "Mazda"};

Example

int[ ] myNum ;

One Dimensional Array

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Single Dimensional Array

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Instantiation of an Array in Java

1. type array-varname[ ];
2. array-varname = new type [size];

Example

int myNum[];

myNum = new int[4];

String[] cars;

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};

System.out.println(cars[0]);

Output:

Volvo

Print - Single Dimensional Array

Change an Array Element

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String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};

cars[0] = "Opel";

System.out.println(cars[0]);

Output:

Opel

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Array Length

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String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};

System.out.println(cars.length);

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Output: 4

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Multidimensional Arrays

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A multidimensional array is an array containing one or more arrays.

To create a two-dimensional array, add each array within its own set of curly braces:

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Example

int myNumbers[][] = { {1, 2, 3, 4}, {5, 6, 7} };

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Syntax to Declare Multidimensional Array in Java

1. dataType[][] arrayRefVar; (or)
2. dataType arrayRefVar[][];

Multidimensional Arrays

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A multidimensional array is an array containing one or more arrays.

To create a two-dimensional array, add each array within its own set of curly braces:

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Syntax to instantiate Multidimensional Array in Java

int arr[][]=new int[4][5];

Example to instantiate Multidimensional Array in Java

int twoD[][] = new int[4][5];

twoD[0][0] = 1;

twoD[0][1] = 5;

Print- Multidimensional Arrays

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myNumbers is now an array with two arrays as its elements.

int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };

int x = myNumbers[1][2];

System.out.println(x);

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Multidimensional Array Length

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int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7}};

System.out.println(myNumbers.length);

Output:

2

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Control Statements

• Java’s program control statements can be put into the following categories: selection, iteration, and jump.
• Selection statements allow your program to choose different paths of execution based upon the outcome of an expression or the state of a variable.
• Iteration statements enable program execution to repeat one or more statements (that is, iteration statements form loops).
• Jump statements allow your program to execute in a nonlinear fashion.

Selection Statements

Java supports two selection statements: if and switch.

• if

if (condition) statement1;

else statement2;

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• Nested ifs

Nested ifs, the main thing to remember is that an else statement always refers to the nearest if statement that is within the same block as the else

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int a, b;

//...

if(a < b) a = 0;

else b = 0;

• The if-else-if Ladder

Sequence of nested ifs is the if-else-if ladder

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Output

April is in the Spring.

• switch

The switch statement is Java’s multiway branch statement. It often provides a better alternative than a large series of if-else-if statements.

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switch (expression) {

case value1:

// statement sequence

break;

case value2:

// statement sequence

Break;

…

case valueN :

// statement sequence

break;

default:

// default statement sequence

}

• switch

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i is zero.

i is one.

i is two.

i is three.

i is greater than 3.

i is greater than 3.

Output

Iteration Statements

Java’s iteration statements are for, while, and do-while.

• while

while(condition) {

// body of loop

}

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int n = 10;

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while(n > 0)

{

System.out.println(“n is” +n);

n=n-1;

}

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Iteration Statements

• do-while

do {

// body of loop

}

while (condition);

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int n = 10;

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do

{

System.out.println(“n is” +n);

n=n-1;

}

while(n > 0)

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Iteration Statements

• for

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int n;

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for(n=10; n>0; n--)

{

System.out.println(“n is” +n);

}

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Jump Statements

Java supports three jump statements: break, continue, and return.

The general form of the labeled break statement is shown here: break label;

• break

break;

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if(a =10)

break;

Jump Statements

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• continue

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• return

The return statement is used to explicitly

return from a method

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Thank You