Core Java - Interview Questions and Answers for 'String pool' | Search Interview Question - javasearch.buggybread.com
Javasearch.buggybread.com

Search Interview Questions


 More than 3000 questions in repository.
 There are more than 900 unanswered questions.
Click here and help us by providing the answer.
 Have a video suggestion.
Click Correct / Improve and please let us know.
Label / Company      Label / Company / Text

   



Core Java - Interview Questions and Answers for 'String pool' - 13 question(s) found - Order By Rating

 Q1. Why string pool concept has been introduced in string ?Core Java
Ans. Memory Sharing and Optimal memory utilization.

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

   Like         Discuss         Correct / Improve     String Pool     Asked in 1 Companies

 Q2. How does making string as immutable helps with securing information ? How does String Pool pose a security threat ?Core Java
Ans. String is widely used as parameter for many java classes, e.g. network connection, opening files, etc. Making it mutable might possess threats due to interception by the other code segment or hacker over internet.

Once a String constant is created in Java , it stays in string constant pool until garbage collected and hence stays there much longer than what's needed. Any unauthorized access to string Pool pose a threat of exposing these values.


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

   Like         Discuss         Correct / Improve     Security  String pool   string immutable  immutability      expert        rare

 Q3. What is the purpose of String Pool ? Don't you think it's a performance overhead to have unnecessary check for string in string pool ?Core Java
Ans. String Pool makes Java more memory efficient by providing a reusable place for string literals. It might be a little performance inconvenience but results in good amount memory saving.

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

   Like         Discuss         Correct / Improve     string pool  memory management      Intermediate

 Q4. What will be result of following code and why

Integer int1 = 1;
Integer int2 = 1;
String str1 = new String("str");
String str2 = new String("str");
String str3 = "str";
String str4 = "str";

      
System.out.println(int1 == int2);
System.out.println(str1 == str2);
System.out.println(str3 == str4); 		Core Java
Ans. true
false
true

Just like Strings, java maintains an integer constant pool too. So 1 will be maintained in integer constant pool and hence reference int2 will point to same integer in pool.

String pool is only for string literals ( defined by "" ) and not for newly created objects and hence str1 == str2 will return false as they are separate objects in memory.

String pool is used for storing string literals so that they can be reused and str3 and str4 will point to same string literal in string pool.


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

   Like         Discuss         Correct / Improve     string pool  integer constant pool  string comparison  integer comparison

 Q5. What will be the output of following code

Integer x = 1;
Integer y = 2;
System.out.println(x == y);

What if you change 1 to "1" and Integer to String?		Core Java
Ans. It will print "true" with integers as well as strings. The reason is "Integer constant pool" and "String pool"

String pool maintains pool of string literals. When a string literal is used for the first time, a new string object is created and is added to the pool. Upon it's subsequent usage , the reference for the same object is returned. Similarly java uses integer constant pool.

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

   Like         Discuss         Correct / Improve     string pool  object equality  ==

 Q6. How and Why Strings are interned in Java ?Core Java
Ans. String class has a public method intern() that returns a canonical representation for the string object. String class privately maintains a pool of strings, where String literals are automatically interned.

these are automatically interned so as to have efficient String comparison using == operator instead of equals which is usually slower.

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

   Like         Discuss         Correct / Improve     string  string pool  string intern     Asked in 1 Companies

 Q7. Which memory segment holds String Pool in Java ?Core Java
Ans. String Pool resides in runtime constant Pool which is a part of Heap memory segment.

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

   Like         Discuss         Correct / Improve     string pool  memory management      Expert        rare

Frequently asked in Infosys India
  Q8. What is a String Pool ?Core Java
Ans. String pool (String intern pool) is a special storage area in Java heap. When a string is created and if the string already exists in the pool, the reference of the existing string will be returned, instead of creating a new object and returning its reference.

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

   Like         Discuss         Correct / Improve     java   oops   string   string class   string pool   heap memory     Asked in 31 Companies      intermediate        frequent
Try 2 Question(s) Test

 Q9. What are different ways to create String Object? Explain.Core Java
Ans. There are total six ways

1. literals

When we create a String using double quotes, JVM looks in the String pool to find if any other String is stored with same value. If found, it just returns the reference to that String object else it creates a new String object with given value and stores it in the String pool.

2. new keyword

When we use new operator, JVM creates the String object but dont store it into the String Pool. We can use intern() method to store the String object into String pool or return the reference if there is already a String with equal value present in the pool.

3. string buffer
4. string builder
5. System.out.println
6. char to string




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

   Like         Discuss         Correct / Improve     java   string class   string   jvm   memory management   string pool     Asked in 5 Companies      basic        frequent
Try 3 Question(s) Test

Asked multiple times in Capgemini.
 Q10. Why Char array is preferred over String for storing password?Core Java
Ans. String is immutable in java and stored in String pool. Once it's created it stays in the pool until unless garbage collected, so even though we are done with password it's available in memory for longer duration and there is no way to avoid it. It's a security risk because anyone having access to memory dump can find the password as clear text.

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

   Like         Discuss         Correct / Improve     java   string class   string   immutable  immutability   string pool   garbage collection   advanced     Asked in 6 Companies      Expert

 Q11. public class a {
   public static void main(String args[]){
      final String s1=""job"";
      final String s2=""seeker"";
      String s3=s1.concat(s2);
      String s4=""jobseeker"";
      System.out.println(s3==s4); // Output 1
      System.out.println(s3.hashCode()==s4.hashCode()); Output 2
   }
}

What will be the Output 1 and Output 2 ?		Core Java
Ans. S3 and S4 are pointing to different memory location and hence Output 1 will be false.

Hash code is generated to be used as hash key in some of the collections in Java and is calculated using string characters and its length. As they both are same string literals, and hence their hashcode is same.Output 2 will be true.

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

   Like         Discuss         Correct / Improve     java   string   hashcode   hash code   string comparison   string pool
Try 1 Question(s) Test

 Q12. What will be the output of the following code ?

String s1 = "Buggy Bread";
String s2 = "Buggy Bread";
if(s1 == s2)
   System.out.println("equal 1");
String n1 = new String("Buggy Bread");
String n2 = new String("Buggy Bread");
if(n1 == n2)
   System.out.println("equal 2");		Core Java
Ans. equal 1

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

   Like         Discuss         Correct / Improve     java   string class   string   string pool   code   coding      basic        frequent

 Q13. What will be the output of following Code ?

class BuggyBread {
   public static void main(String[] args) {
      String s2 = "I am unique!";
      String s5 = "I am unique!";

      System.out.println(s2 == s5);
   }
}		Core Java
Ans. true, due to String Pool, both will point to a same String object.

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

   Like         Discuss         Correct / Improve     java   code   coding   tricky questions   interesting questions   string   string pool   .equal   ==      intermediate        frequent

 Q14. 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
 Q15. Which memory segment holds String Pool ?Core Java
a. Stack
b. Heap
c. Code Segment
d. Class Segment

Ans.b. Heap

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.

Any input from you will be highly appreciated and It will unlock the application for 10 more requests.

Company Name:
Questions Asked: