Methods in Java tutorial and Interview Questions and Answers
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Study and learn Interview MCQ Questions and Answers on Methods in Java . Attend job interviews easily with these Multiple Choice Questions
Methods in Java
Java Method Signature is nothing but a combination of Return-Type, Method’s Name and a Parameter list it accepts.
The method signature or syntax is as follows.
type METHODNAME(type param1, type param2..)
{
//statements
//..
//return statement
}
Let us know about parts of Java Method Signature.
- Return Type
- Method Name
- Parameter List
1. Return Type: A Java method may or may not return a value. If it returns nothing, we specify it explicitly mentioning a “void” before it. A method can return pri-mitive or Object type values.
2. Method Name: A Java Method Name can be a combination of Alphabets, Numbers and Special Symbols (Underscore and Dollar only).
Methods in Java Naming Rules:
- Method name can start with a Letter or Alphabet.
- Method name can start with either Underscore(_) or Dollar($) symbol.
- and Method name can not start with a number.
- Method name can contain numbers in-between or at the end.
- and Method name can not be a keyword.
3. Parameter List: Java methods can contain any number of parameters of any type. There can be zero parameters also. Variables which are part of a Parameter-list are also called Local Variables. Local variables are stored in Stack Memory. Also, the variables declared inside a method are also called Local Variables or Method Variables.
Naming Conventions or Rules for Local Variables:
- Name of a Local variable can start with an Alphabet lowercase or uppercase. Lowercase is preferred.
- Name of a Local variable can start with either an Underscore(_) or Dollar($) symbol.
- and Name of a Local variable can not start with a number but it can contain numbers in-between or at the end.
- Name can not be a keyword.
- No two Local variables should have the same name.
An example Java program below explains how to pass arguments to a Java method and return values or objects from a method.
class Table
{
int height;
}
public class JavaMethodExample
{
public static void main(String[] args)
{
JavaMethodExample je = new JavaMethodExample();
Table t1 = new Table();
t1.height = 10;
je.show(t1); //Passing arguments to method
int changedValue = je.increase(t1);
System.out.println("New Height= " + changedValue);
//System.out.println("New Height= " + t1.height); //This code also works
}
void show(Table tab) //Receiving parameters in method
{
System.out.println("Height= " + tab.height);
}
int increase(Table tab) //Returning a value
{
tab.height = tab.height + 20;
return tab.height;
}
}
//OUTPUT
//Height= 10
//New Height= 30
Note
In the above example, the method “show” receives parameters. The method “increase” receives an object reference as a parameter and returns an integer value back to the calling method. Remember that “main” is also a method which is the starting point of program execution.
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[WpProQuiz 158]
Methods in Java MCQ (Interview)
1) A Java method is comparable to a __ in c language.
A) structure
B) union
C) function
D) enum
Answer [=] C
2) All Java methods must have a return type. (TRUE / FALSE)
A) TRUE
B) FALSE
Answer [=] A
3) State TRUE or FALSE. A Java method can have the same name as the class name.
A) TRUE
B) FALSE
Answer [=] A
4) In Java, add a ___ to a constructor to convert it into a method.
A) if statement
B) static
C) return type
D) semicolon
Answer [=] C
5) Java method signature is a combination of ___.
A) Return type
B) Method name
C) Argument List
D) All the above
Answer [=] D
6) In Java, a method name can not start with a ___.
A) number
B) # (pound)
C) – (hyphen)
D) All the above
Answer [=] D
7) In Java, a method name can start with ___.
A) Alphabet
B) Underscore (_)
C) Dollar ($)
D) All the above
Answer [=] D
8) In Java, a method name can contain numbers from 2nd character onwards. (TRUE / FALSE).
A) TRUE
B) FALSE
Answer [=] A
9) Choose the correct identifier for a method name in Java.
A) 1show
B) $hide
C) *show$
D) 3_click
Answer [=] B
10) What is the output of the below Java program with an empty return statement?
public class TestingMethods2
{
void show()
{
System.out.println("SHOW Method..");
return;
}
public static void main(String[] args)
{
TestingMethods2 t2 = new TestingMethods2();
t2.show();
}
}
A) SHOW Method..
B) No output
C) Compiler error
D) None
Answer [=] A
Explanation:
Yes. A void method can use an empty return statement.
11) What is the output of the below Java program with a void method?
public class TestingMethods3
{
void show2()
{
System.out.println("SHOW Method 2");
}
public static void main(String[] args)
{
TestingMethods3 t3 = new TestingMethods3();
t3.show2();
}
}
A) SHOW Method 2
B) No output
C) Compiler error
D) None
Answer [=] A
Explanation:
The empty return statement is not necessary for a void method.
12) A “this” operator used inside a Java method refers to ___ variable.
A) Global variable
B) Method local variable
C) Instance variable
D) None
Answer [=] C
13) What is the output of the below Java program with a “this” operator?
public class TestingMethods4
{
int cakes=5;
void order(int cakes)
{
this.cakes = cakes;
}
public static void main(String[] args)
{
TestingMethods4 t4 = new TestingMethods4();
t4.order(10);
System.out.println("CAKES=" + t4.cakes);
}
}
A) CAKES=5
B) CAKES=0
C) CAKES=10
D) Compiler error
Answer [=] C
Explanation:
In the program, this.cakes refers to the instance variable cakes.
14) A local variable declared inside a method can not be used in expressions without initializing it first. (TRUE / FALSE).
A) TRUE
B) FALSE
Answer [=] A
15) What is the output of the below Java program?
public class TestingMethods5
{
public static void main(String[] args)
{
int localVariable;
System.out.println(localVariable);
}
}
A) 0
B) garbage value
C) NullPointerException
D) Compiler error
Answer [=] D
Explanation:
In the above program, the localVariable is a Local variable and it is not initialized. You can not use it in any expressions, not even printing.
16) In Java, local variables are stored in __ memory and instance variables are stored in ___ memory.
A) Stack, Stack
B) Heap, Heap
C) Stack, Heap
D) Heap, Stack
Answer [=] C
17) A static-method or a static-variable is shared among all instances of a class. (TRUE / FALSE)
A) TRUE
B) FALSE
Answer [=] A
Explanation:
Yes. a single copy of a static variable or method is common to all instance objects.
18) What is the output of the Java program with static variables?
public class TestingMethods6
{
static int cats=25;
public static void main(String[] args)
{
TestingMethods6 t6 = new TestingMethods6();
System.out.println("t6 BIRDS before=" + t6.cats);
TestingMethods6 t7 = new TestingMethods6();
t7.cats = 10;
System.out.println("t6 BIRDS after=" + t6.cats);
}
}
A)
t6 BIRDS before=25 t6 BIRDS after=25
B)
t6 BIRDS before=25 t6 BIRDS after=10
C)
t6 BIRDS before=25 t6 BIRDS after=0
D) None
Answer [=] B
Explanation:
The static variable “cats” is common to all objects. There is no separate copy like non-static variables.
19) What is the output of the below Java program with a final local variable?
public class TestingMethods8
{
int cars = 20;
void change(final int cars)
{
cars = 10;
this.cars = cars;
}
public static void main(String[] args)
{
TestingMethods8 t8 = new TestingMethods8();
t8.change(30);
System.out.println(t8.cars);
}
}
A) 30
B) 20
C) 10
D) Compiler error
Answer [=] D
Explanation:
The argument that is marked final can not be reassigned or changed. So, the compiler error is produced. So, the statement cars=10; inside the change() method is wrong.
20) Java does not allow nesting of methods. (TRUE / FALSE)
A) TRUE
B) FALSE
Answer [=] A
21) What is the output of the below Java program?
class Road
{
static void show()
{
System.out.println("Inside static method.");
}
}
public class TestingMethods10
{
public static void main(String[] args)
{
Road.show();
}
}
A) Inside static method.
B) empty message
C) Compiler error
D) Runtime error / exception
Answer [=] A
Explanation:
You can directly call static methods of a class with just a DOT operator and class-name.
22) What is the output of the below Java program?
class SomeClass
{
char batch = 'A';
}
public class TestingMethods11
{
public static void main(String[] args)
{
SomeClass a1 = new SomeClass();
System.out.println("Before: " + a1.batch);
SomeClass a2 = new SomeClass();
a2.batch = 'B';
System.out.println("After: " + a1.batch);
}
}
A)
Before: A After: B
B)
Before: A After: A
C)
Before: A After:
D)
Before: B After: B
Answer [=] B
Explanation:
Instance variable “batch” is separate for each instance. So the changes to one instance object does not affect another instance object.
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