Interview Questions and Answers for 'Java' | Search Interview Question

Interview Questions and Answers - Order By Rating

Recently asked in Capital One.

Q1651. What will happen if we call perform(null) ?

public void perform(Object obj) {
System.out.println("Object");
}

public void perform(Integer int) {
System.out.println("Integer");
}

Core Java

Ans. compiler will throws error as ambiguous methods

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve overloading method overloading Asked in 1 Companies intermediate}

Q1652. How is multiple inheritance implemented in Java ?

Core Java

Ans. There was no multiple inheritance in java before version 8 as implementing multiple interfaces cannot be termed as inheritance.

With Java 8 , came the concept of default methods wherein the class implementing the interface carries the default implementation from the interface and hence facilitating multiple inheritance.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve multiple inheritance object oriented programming (oops) oops concepts inheritance object oriented programming (oops) oops concepts oops concept Asked in 10 Companies frequent}

Q1653. In which cases , moving methods to utility class could be useful ?

Core Java

Ans. It could be worthy to move a method to util class if the method needs to be shared, doesn't require polymorphic behavior and need not be overridden in special cases.

Don't belong to one group through is-a relationship ( You can share through parent class method )

Don't implement a specific interface ( java 8 default methods )

Doesn't involve complex computing as you will be loosing the benefit of object state with just static method.

Doesn't require polymorphic behavior as static methods don't participate in runtime polymorphism.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve utility classes util classes static methods application design rare}

Q1654. What are the new classes in JDK 1.9 ( Java 9 ) ?

Ans. http://www.buggybread.com/2015/05/java-9-new-classes-and-interfaces-in.html

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java9 java 9 jdk1.9 jdk 1.9}

Q1655. What is a Destructor ? Do we have Destructors in Java ?

Core Java

Ans. Destructor is used to de-allocate memory allocated by objects.

There are no destructors in Java. Alternatively, Java provides Automatic garbage collection i.e automatically releasing the un-referenced memory.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve destructor garbage collection Asked in 11 Companies Basic frequent}

Try 1 Question(s) Test

Q1656. Why Java is not considered pure OOP's language ?

Core Java

Ans. There are 2 reasons for it.

1. Usage of Primitive types - Though Java provides classes for the primitive data types but as the usage of primitives is permissible, its considered unpure OOP's language.

2. Usage of Static members - Static members belong to the class and not objects and hence not considered fit for pure OOP's programming.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve oops object oriented programming object oriented language primitive data types Asked in 2 Companies}

Q1657. What is the use of Runtime Class ?

Ans. This class is used to provide access to the Java runtime system

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve runtime class jre java runtime}

Frequently asked.

Q1658. What should a class do if its implementing an interface ?

Core Java

Ans. It should either implement all interface methods or declare unimplemented methods as abstract.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve interfaces Asked in 1 Companies Basic frequent}

Try 1 Question(s) Test

Q1659. What should a class do if its extending an abstract class ?

Core Java

Ans. It should either implement the abstract methods or re-declare them abstract.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve abstract class Asked in 2 Companies Basic Frequent}

Q1660. What is a compilation unit in Java ?

Ans. Java Source Code File

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve compilation unit in java}

Q1661. What is Associativity while evaluating a Java statement ?

Core Java

Ans. Associativity determines whether an expression is evaluated left-right or right-left. When an expression has two operators with the same precedence, the expression is evaluated according to its associativity.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve associativity expression evaluation operator}

Q1662. What is a package and what are its advantages ?

Core Java

Ans. Package is a namespace that organizes a set of related classes.

Advantages of Packages

1. Better Organization of classes.
2. Saves from the problem of duplicate names as duplicate class names are allowed across different packages.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve package advantages of packages Asked in 1 Companies Basic}

Q1663. When String literals are compared using ==, they always returns true if the string values are same because .. Reference

Core Java

a. of overridden compareTo method

b. of overridden compare method

c. of String Pool

d. == means that the object contents are equal

Ans.c. of String Pool

Q1664. Which of the following is true ?

Core Java

a. Composition is Tightly Bound

b. Inheritance is Tightly Bound

c. Object can only hold reference of only one other object

d. A Class cannot be extended by multiple classes

Ans.b. Inheritance is Tightly Bound

Q1665. In case of String Literals .. Reference

Core Java

a. x==y on all literals always returns false

b. x.equals(y) on all literals always returns false

c. if x.equals(y) returns true, x==y returns true too

d. if x.equals(y) returns false, x==y returns true

Ans.c. if x.equals(y) returns true, x==y returns true too

Q1666. What is a default constructor ? Reference

Core Java

a. Constructor without parameters declared by user

b. Constructor provided by Java if no constructor is declared

c. Constructor with empty body

d. All of the above

Ans.b. Constructor provided by Java if no constructor is declared

Q1667. How can we create objects if we make the constructor private ?

Core Java

a. We can't create objects if constructor is private

b. We can only create objects if we follow singleton pattern

c. We can only create one object

d. We can create new object through static method or static block

Ans.d. We can create new object through static method or static block

Q1668. What will be the output of following ?

String str1 = new String("String1");
String str2 = new String("String1");
System.out.print(str1 == str2);
System.out.print(str1.equals(str2));
str1 = str2;
System.out.print(str1 == str2);

Core Java

a. falsetruetrue

b. truetruetrue

c. truetruefalse

d. falsetruefalse

Ans.a. falsetruetrue

Q1669. What will be the output of following code ?

String str1 = "String1";
String str2 = "String1";
System.out.print(str1 == str2);
System.out.print(str1.equals(str2));
str1 = str2;
System.out.print(str1 == str2);

Core Java

a. falsetruetrue

b. falsefalsetrue

c. truetruetrue

d. falsefalsefalse

Ans.c. truetruetrue

Q1670. What will be the output of following code ?

String str1 = "String1";
String str2 = "String2";
str1.concat("String3");
System.out.print(str1);
System.out.print(str2);

Core Java

a. String1String2

b. String1String3String3

c. String1String3String1String3

d. String1String1

Ans.a. String1String2

Q1671. What will be the output of following code ?

String str1 = "String1";
String str2 = "String2";
str1=str1.concat("String3");
System.out.print(str1);
System.out.print(str2);

Core Java

a. String1String2

b. String1String3String2

c. String1String2String3

d. String1Stringg3String1

Ans.b. String1String3String2

Q1672. Which method needs to be implemented if a class is implementing comparable interface ?

Core Java

a. comp

b. compare

c. compareTo

d. compareEquals