Language Fundamentals

Agenda

1. Identifiers

2. Reserved Words

3. Data Types

4. Literals

5. Arrays

6. Types of Variables

7. Var-arg method

8. Main method

9. Command line arguments

10. Java coding standards

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1. Identifiers:

A name in java program is called identifier which can be used for identification purpose. It can be a method name, variable name, class name or label name.

Example - How many identifiers are presents in the following program.

class Test{

public static void main(String[] args){

int x=10;

}

}

Answer - There are 5 identifiers present Test, main, String, args, x.

Rules for defining java identifiers.

• The only allowed characters in Java identifiers are a to z, A to Z, 0 to 9, $, _. If we are using any other character we will get compile time error. Ex - Total_number - Valid , Total# - Invalid

• Identifiers can't start with a digit. Ex - Total123 - Valid, 123Total - Invalid

• Java Identifiers are case sensitive because Java language itself is treated as case sensitive programming language.

Ex

class Test{

//Differentiated w.r.t case
int number = 10;
int Number = 10;
int NUMBER = 20;

}