Java Methods - Ebhor.com

Introducing Method

In java programming language class usually consist of two things instance variable and methods.

Method are the block of statement that perform a special task.

Using methods we can avoid the rewriting the same code over and over in a sane program.

Method increase the efficiency and reduce the complexity of the program.

Syntax of Method Definition

 accessModifier returnType   methodName(){
     statements; 
}

accessModifier returnType methodName(){

statements;

}

Write a program to demonstrate method in class.

class RectangleArea {

    int length;
    int width;

    void area() { // method area() definition	
        length = 10;	 // within class variables access without object
        width = 20;
        int a = length * width;
        System.out.println("Area of the rectangle =" + a);
    }
}

public class TestRectangle {

    public static void main(String arg[]) {
        RectangleArea obj1 = new RectangleArea();
        obj1.area();// call area() method	
    }
}

class RectangleArea {

int length;

int width;

void area() { // method area() definition

length = 10; // within class variables access without object

width = 20;

int a = length * width;

System.out.println("Area of the rectangle =" + a);

}

public class TestRectangle {

public static void main(String arg[]) {

RectangleArea obj1 = new RectangleArea();

obj1.area();// call area() method

}

Result

Area of the rectangle =200

1	Area of the rectangle =200

Parameterized(overloaded) Method

Write a program to demonstrate parameterized method in class.

class RectangleArea {

    int length;
    int width;

    void area(int i, int j) { // method area() definition	
        length = i;	     // within class variables access without object
        width = j;
        int a = length * width;
        System.out.println("Area of the rectangle =" + a);
    }
}

public class TestRectangle1 {

    public static void main(String arg[]) {
        RectangleArea obj1 = new RectangleArea();
        obj1.area(10, 20);// call area() method and pass value of argyments
    }
}

class RectangleArea {

int length;

int width;

void area(int i, int j) { // method area() definition

length = i; // within class variables access without object

width = j;

int a = length * width;

System.out.println("Area of the rectangle =" + a);

}

public class TestRectangle1 {

public static void main(String arg[]) {

RectangleArea obj1 = new RectangleArea();

obj1.area(10, 20);// call area() method and pass value of argyments

}

Output

Area of the rectangle =200

1	Area of the rectangle =200

Java Program to illustrate Method call with and without agrument and with and without return type

public class MethodsDemo1 {
    public static void main(String[] args) {
        System.out.println("Inside Main method");
        MethodsDemo1 m = new MethodsDemo1();
        m.add();
        int x = 5, y = 7;
        m.sub(x, y); //10,5 are actual parameter
        int mulVal = m.mul();
        System.out.println("Multiplication is " + mulVal);
        int divVal = m.div(10, 5); //10,5 are actual parameter
        System.out.println("Division is  " + divVal);

    }

    //method without argument and without return type
    public void add() {
        int a = 5, b = 5;
        int result = a + b;
        System.out.println("Sum is  " + result);
    }
    //method with argument and without return type
    public void sub(int a, int b) { //a and b are formal arguments
        int result = a - b;
        System.out.println("Subtraction is " + result);
    }
    //method without argument and with return type
    public int mul() {
        int a = 5, b = 2;
        int result = a * b;
        return result;
    }

    //method with argument and with return type
    public int div(int a, int b) { //a and b are formal arguments
        int c = a / b;
        return c;
    }
}

public class MethodsDemo1 {

public static void main(String[] args) {

System.out.println("Inside Main method");

MethodsDemo1 m = new MethodsDemo1();

m.add();

int x = 5, y = 7;

m.sub(x, y); //10,5 are actual parameter

int mulVal = m.mul();

System.out.println("Multiplication is " + mulVal);

int divVal = m.div(10, 5); //10,5 are actual parameter

System.out.println("Division is " + divVal);

}

//method without argument and without return type

public void add() {

int a = 5, b = 5;

int result = a + b;

System.out.println("Sum is " + result);

}

//method with argument and without return type

public void sub(int a, int b) { //a and b are formal arguments

int result = a - b;

System.out.println("Subtraction is " + result);

}

//method without argument and with return type

public int mul() {

int a = 5, b = 2;

int result = a * b;

return result;

}

//method with argument and with return type

public int div(int a, int b) { //a and b are formal arguments

int c = a / b;

return c;

}

Output

D:\Test Java>javac MethodsDemo1.java

D:\Test Java>java MethodsDemo1
Inside Main method
Sum is  10
Subtraction is -2
Multiplication is 10
Division is  2

D:\Test Java>javac MethodsDemo1.java

D:\Test Java>java MethodsDemo1

Inside Main method

Sum is 10

Subtraction is -2

Multiplication is 10

Division is 2

Java Program to pass a object to a method

Student.java

public class Student {
    private long rollNo;
    private String name;
    private String branch;

    public void setRollNo(long rollNo1) {
        rollNo = rollNo1;
    }
    public long getRollNo() {
        return rollNo;
    }
    public void setName(String name1) {
        name = name1;
    }
    public String getName() {
        return name;
    }
    public void setBranch(String branch1) {
        branch = branch1;
    }
    public String getBranch() {
        return branch;
    }
}

public class Student {

private long rollNo;

private String name;

private String branch;

public void setRollNo(long rollNo1) {

rollNo = rollNo1;

}

public long getRollNo() {

return rollNo;

}

public void setName(String name1) {

name = name1;

}

public String getName() {

return name;

}

public void setBranch(String branch1) {

branch = branch1;

}

public String getBranch() {

return branch;

}

StudentDemo.java contains main method and updateStudent method

public class StudentDemo {
    public static void main(String[] args) {
        Student student = new Student();
        student.setRollNo(1);
        student.setName("Ram");
        student.setBranch("CSE");
        System.out.println("Student Details");
        System.out.println("Roll No " + student.getRollNo() + " Name " + student.getName() + " branch " + student.getBranch());
        StudentDemo s = new StudentDemo();
        s.updateStudent(student);
        System.out.println("Roll No " + student.getRollNo() + " Name " + student.getName() + " branch " + student.getBranch());
    }
    public void updateStudent(Student x) {
        x.setRollNo(2);
        x.setBranch("CSE AI ML");
        System.out.println("Roll No " + x.getRollNo() + " Name " + x.getName() + " branch " + x.getBranch());
    }
}

public class StudentDemo {

public static void main(String[] args) {

Student student = new Student();

student.setRollNo(1);

student.setName("Ram");

student.setBranch("CSE");

System.out.println("Student Details");

System.out.println("Roll No " + student.getRollNo() + " Name " + student.getName() + " branch " + student.getBranch());

StudentDemo s = new StudentDemo();

s.updateStudent(student);

System.out.println("Roll No " + student.getRollNo() + " Name " + student.getName() + " branch " + student.getBranch());

}

public void updateStudent(Student x) {

x.setRollNo(2);

x.setBranch("CSE AI ML");

System.out.println("Roll No " + x.getRollNo() + " Name " + x.getName() + " branch " + x.getBranch());

}

Output

D:\Test Java>javac StudentDemo.java 
D:\Test Java>java StudentDemo
Student Details
Roll No 1 Name Ram branch CSE
Roll No 2 Name Ram branch CSE AI ML
Roll No 2 Name Ram branch CSE AI ML

D:\Test Java>javac StudentDemo.java

D:\Test Java>java StudentDemo

Student Details

Roll No 1 Name Ram branch CSE

Roll No 2 Name Ram branch CSE AI ML

Passing array as argument in java method

public class ArrayArgument{
  public static void main(String[] s){
    int[] numbers={4,5,1,6,2};
	ArrayArgument ar=new ArrayArgument();
	ar.multiply(numbers);
	System.out.println("\nnumbers in main\n");
	for(int a:numbers){
		System.out.print(a+" ");
		}
	}
 	public void multiply(int[] arr){
		for(int i=0;i<arr.length;i++){
			arr[i]=arr[i]*2;
		}
			System.out.println("\nnumbers in multiply method\n");
		for(int a:arr){
			System.out.print(a+" ");
		}

	}
}

public class ArrayArgument{

public static void main(String[] s){

int[] numbers={4,5,1,6,2};

ArrayArgument ar=new ArrayArgument();

ar.multiply(numbers);

System.out.println("\nnumbers in main\n");

for(int a:numbers){

System.out.print(a+" ");

}

public void multiply(int[] arr){

for(int i=0;i<arr.length;i++){

arr[i]=arr[i]*2;

}

System.out.println("\nnumbers in multiply method\n");

for(int a:arr){

System.out.print(a+" ");

}

Output

 2
 4