Variables in Java

Variable in java can be defined as a name for a memory location which can hold the data.

Variable declartion:

syntax:

<modifier> <Data Type> <var-Name>;

or

<modifier> <Data Type> <var-Name>= value;

There are 3 types of variables are there in java. They are,

1)Local Variables

2)Instance Variables

3)Static Variables

1) Local Variable:
a variable which is declared inside a method is called as Local variable.
ex:

void m1(){

int a=10; // local varible declaration

int b=20; // local varible declaration

}

Note:

Local variables must and should be initialized before using. Otherwise we will get Compile time error.

2) Instance Variable:
a variable which is declared inside a class but not inside any method, without static keyword is called as Instance variable.
ex:

class MyProgram{

int a=10; // Instance varible declaration

int b; // Instance varible declaration

}

Note:

If we not initialize Instance variables then it will be initialized by default values of that data type.

3) Static Variable:
a variable which is declared inside a class but not inside any method, with static keyword is called as Static variable.
ex:

class MyProgram{

static int a=10; // local varible declaration

static int b; // local varible declaration

}

Note:

If we not initialize Static variables then it will be initialized by default values of that data type.

Control Statements in Java

We have 3 types of Control Statements in Java. They are,

-- Conditional Control Statements

-- Iterative Control Statements

-- Transfer/Jump Control Statements

Control Statements in java

1) Conditional control statements:

Conditional Statements will work based on the conditions. We have different types of Conditional Statements. They are,

i) if : If the condition is true then the control will execute the block of statements otherwise the control will not enter into if block

Syntax:

if(condition)

{

statement1;

statement2;

----------

}

ii) if-else : If the condition is true then the control will execute the if block otherwise the control will execute else block

Syntax:

if(condition)

{

statement1;

statement2;

}

else{

statement3;

statement4;

}

2) Iterative Control Statements:

Iterative control statements are used to execute the group of statements repeatatively based on a condition.

ex:

i) while

ii) do-while

iii) for

3) Transfer/Jump Control Statements:

whenever these statements are encountered then the control will be transfered from one place to another.

ex:

i) break

ii) continue

iii) return