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10 USER-DEFINED
METHODS
Learning Objectives
10.1 Need for Methods 10.2 Forms of Methods
10.3 Defining a Method 10.4 Ways to Define a Method
10.5 Actual and Formal Parameters 10.6 Invoking a Method
10.7 The static and non-static Methods 10.8 Pure and Impure Methods
10.9 Method Overloading
A method is a block of statements used to perform a particular operation. Once a method is written, it can be used
many times as and when required. For example, in a calculator program different operation such as sum or difference
would be required to execute depending on the need of the user. A method is also known as function.
10.1 NEED FOR METHODS
There is no use of a class without methods. Methods are Definition
necessary to perform operations on the data members of a class.
These are very useful as they reduce the size of a program. They Definition: A method in Java is a group of
occupy less space in memory and the execution becomes faster. statements which can be used together to
They increase the reusability of code. They reduce the burden of perform a specific operation. These can be used
debugging of programming code, so finding and correcting the repeatedly, thus reducing the length of code.
errors becomes easy for the developers.
10.2 FORMS OF METHODS
There are two forms of methods: predefined methods and user-defined methods. Let us study them in detail.
10.2.1 Predefined Methods
The methods that are already defined in the packages of Java and available to use in the form of class library are
called predefined methods. They are also known as built-in methods. To use these methods, we first have to import
the package in which the class exists that contains the desired methods. Examples of predefined methods are
CharAt( ) and next( ). To use the predefined methods, we need to create an object of the class under which the
function is defined.
222222 Touchpad Computer Applications-X

