Method overloading interview questions java

Core java Interview Questions

1.What is Method in java?

• Method is a sub block of a class that contains logic of that class.
• logic must be placed inside a method, not directly at class level, if we place logic at class level compiler throws an error.
• So class level we are allowed to place variables and methods.
• The logical statements such as method calls, calculations and printing related statements must be placed inside method, because these statements are considered as logic. 
• For more information @ Methods in java

1. package com.instanceofjava;
2. class sample{
3.  
4. int a;
5. int b;
6.  
7. System.out.println("instance of java"); // compiler throws an error.
8.  
9. }
10.  

1. package com.instanceofjava;
2. class sample{
3.  
4. static int a=10;
6.    
7. public static void main(String args[]){
8. 
   
9. System.out.println(a); // works fine,prints a value:10
10.  
11.  }
12. }

2.What is meant by method overloading in java?

• Defining multiple methods with same name is known as polymorphism.
• Defining multiple methods with same name and with different arguments known as method overloading.

1. package com.instanceofjava;
2. class A{
3.  
4. public void show(int a){
5. System.out.println("saidesh");
6. }
7.  
8. public void show(int a,int b){
9. System.out.println("ajay");
10. }
11.  
12. public void show(float a){
13. System.out.println("vinod");
14. }
15. public static void main(String args[]){
16.  
17. A a=new A();
18.  
19. a.show(10);
20. a.show(1,2);
21. a.show(1.2);
22.  
23. }
24. }

Output:

1. saidesh
2. ajay
3. vinod

3.What are the other names for method overloading?

• Method overloading also known as static polymorphism or compile time polymorphism because at compile time itself we can tell which method going to get executed based on method arguments.
• So method overloading also called as static binding. 

4.What are the basic rules of method overloading?

• Defining a method with same name and differ in number of arguments
• Defining a method with same name and differ in type of arguments
• Defining a method with same name and differ in order of type of arguments
• Return type of the method not involved in method overloading.

5.Can we overload static methods in java?

• Yes. We can overload static methods in java.
• Method overriding is not possible but method overloading is possible for static methods.
• Before that lets see about method overloading in java.

• lets see an example java program which explains static method overloading.
  

1. class StaticMethodOverloading{
2.  
3. public static void staticMethod(){
4.  
5. System.out.println("staticMethod(): Zero arguments");
6.  
7. } 
8.  
9. public static void staticMethod(int a){
10.  
11. System.out.println("staticMethod(int a): one argument");
12.  
13. } 
14.  
15. public static void staticMethod(String str, int x){
16.  
17. System.out.println("staticMethod(String str, int x): two arguments");
18.  
19. }
20.  
21. public static void main(String []args){
22.   
23.   StaticMethodOverloading.staticMethod();
24.   StaticMethodOverloading.staticMethod(12);
25.   StaticMethodOverloading.staticMethod("Static method overloading",10);
26.  
27. }
28. }

 Output:

1. staticMethod(): Zero arguments
2. staticMethod(int a): one argument
3. staticMethod(String str, int x): two arguments

6.Can we overload main method in java?

Yes we can overload main method in java

Java Program to overload main method in java

1. class mainMethodOverloading{
2.  
3. public static void main(boolean x){
4.  
5. System.out.println("main(boolean x) called ");
6.  
7. } 
8.  
9. public static void main(int x){
10.  
11. System.out.println("main(int x) called");
12.  
13. } 
14.  
15. public static void main(int a, int b){
16.  
17. System.out.println("main(int a, int b) called");
18.  
19. }
20.  
21. public static void main(String []args){
22.    
23.  
24. System.out.println("main(String []args) called ");
25.  
26.   mainMethodOverloading.main(true);
27.   mainMethodOverloading.main(10);
28.  mainMethodOverloading.main(37,46);
29.  
30.  
31. }
32. }

 Output:

1. main(String []args) called
2. main(boolean x) called
3. main(int x) called
4. main(int a, int b) called

7.Can we overload constructors in java?

• Yes we can overload constructor in java

1. package instanceofjava;
2. class ConstructorChaining{
3. int a,b 
4. ConstructorChaining(){
5. this(1,2);
6.  System.out.println("Default constructor");
7.  
8. } 
9.  
10. ConstructorChaining(int x , int y){
11.  
12. this(1,2,3); 
13. a=x;
14. b=y;
15.  System.out.println("Two argument constructor");
16.  
17. }
18.  
19. ConstructorChaining(int a , int b,int c){
20.  System.out.println("Three argument constructor")
21. } 
22.  
23. public static void main(String[] args){
24.  
25.  ConstructorChaining obj=new ConstructorChaining();
26.   System.out.println(obj.a);
27.   System.out.println(obj.b);
28.  
29. }
30. }

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