ADDING VARIABLES AND METHODS

A Java method is a collection of statements that are grouped together to perform an operation. When you call the System.out.println method, for example, the system actually executes several statements in order to display a message on the console.

Now you will learn how to create your own methods with or without return values, invoke a method with or without parameters, overload methods using the same names, and apply method abstraction in the program design.

Creating Method:

Considering the following example to explain the syntax of a method:

public static int funcName(int a, int b) {
  // body
}

Here,

• public static : modifier.
• int: return type
• funcName: function name
• a, b: formal parameters
• int a, int b: list of parameters

Methods are also known as Procedures or Functions:

• Procedures: They don't return any value.
• Functions: They return value.

Method definition consists of a method header and a method body. The same is shown below:

modifier returnType nameOfMethod (Parameter List) {
 // method body
}

The syntax shown above includes:

• modifier: It defines the access type of the method and it is optional to use.
• returnType: Method may return a value.
• nameOfMethod: This is the method name. The method signature consists of the method name and the parameter list.
• Parameter List: The list of parameters, it is the type, order, and number of parameters of a method. These are optional, method may contain zero parameters.
• method body: The method body defines what the method does with statements.

Example:

Here is the source code of a method which takes two parameters n1 and n2 and returns the minimum of the two:

/** the snippet returns the minimum between two numbers */
public static int minFunction(int n1, int n2) {
   int min;
   if (n1 > n2)
      min = n2;
   else
      min = n1;

   return min; 
}

Method Calling:

For using a method, it should be called. There are two ways in which a method is called i.e. method returns a value or returning nothing (no return value).

The process of method calling is simple. When a program invokes a method, the program control gets transferred to the called method. This called method then returns control to the caller in two conditions, when:

• return statement is executed.
• reaches the method ending closing brace.

The methods returning void is considered as call to a statement. Lets consider an example:

System.out.println("This is tutorialspoint.com!");

The method returning value can be understood by the following example:

int result = sum(6, 9);

Example:

Following is the example to demonstrate how to define a method and how to call it:

public class ExampleMinNumber{
   
   public static void main(String[] args) {
      int a = 11;
      int b = 6;
      int c = minFunction(a, b);
      System.out.println("Minimum Value = " + c);
   }

   /** returns the minimum of two numbers */
   public static int minFunction(int n1, int n2) {
      int min;
      if (n1 > n2)
         min = n2;
      else
         min = n1;

      return min; 
   }
}

This would produce the following result:

Minimum value = 6

Variable

A variable provides us with named storage that our programs can manipulate. Each variable in Java has a specific type, which determines the size and layout of the variable's memory; the range of values that can be stored within that memory; and the set of operations that can be applied to the variable.

You must declare all variables before they can be used. The basic form of a variable declaration is shown here:

data type variable [ = value][, variable [= value] ...] ;

Here data type is one of Java's datatypes and variable is the name of the variable. To declare more than one variable of the specified type, you can use a comma-separated list.

Following are valid examples of variable declaration and initialization in Java:

int a, b, c;         // Declares three ints, a, b, and c.
int a = 10, b = 10;  // Example of initialization
byte B = 22;         // initializes a byte type variable B.
double pi = 3.14159; // declares and assigns a value of PI.
char a = 'a';        // the char variable a iis initialized with value 'a'

This chapter will explain various variable types available in Java Language. There are three kinds of variables in Java:

• Local variables
• Instance variables
• Class/static variables