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String Interview Questions
Last Updated : 26 May, 2026
title: String Interview Questions
Fundamentals181 words10 headingsExamples included
title: String Interview Questions description: String ke important interview questions aur answers
Q1. String pool kya hai?
JVM mein ek special memory area jahan String literals store hote hain. Same literal dobara create karne par naya object nahi banta — pool wala reuse hota hai.
Q2. String immutable kyun hai?
Security, thread safety, String pool aur hashcode caching ke liye.
Q3. String ke saath == aur equals() ka fark?
==: Reference compare (same object?).equals(): Content compare (same value?)
Q4. StringBuilder thread-safe kyun nahi?
Methods synchronized nahi hain. Multi-thread mein StringBuffer use karo.
Q5. intern() method kya karta hai?
String object ko String Pool mein daalta hai aur pool reference return karta hai.
Q6. String se char array aur wapas?
java exampleWoHoTech
String s = "Hello";
char[] arr = s.toCharArray(); // String → char[]
String back = new String(arr); // char[] → StringQ7. Two strings anagram hain kaise pata karo?
java exampleWoHoTech
boolean isAnagram(String s1, String s2) {
char[] a = s1.toCharArray();
char[] b = s2.toCharArray();
Arrays.sort(a); Arrays.sort(b);
return Arrays.equals(a, b);
}Q8. String mein substring count?
int countOccurrences(String str, String sub) {
int count = 0, idx = 0;
while ((idx = str.indexOf(sub, idx)) != -1) {
count++; idx++;
}
return count;
}
Q9. String.format() aur printf mein fark?
String.format(): Formatted String return karta haiSystem.out.printf(): Console par print karta hai
Q10. Empty String aur null mein fark?
null: String reference kuch point nahi karta"": Valid String object with 0 length
java exampleWoHoTech
String s1 = null;
String s2 = "";
s2.isEmpty(); // true
s1.isEmpty(); // NullPointerException!Exam Focus
Revise definitions, diagrams, examples, and short-answer points for String Interview Questions.
Interview Use
Prepare one clear explanation, one practical example, and one common mistake for this Java topic.
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FundamentalsArray Interview Questionstitle: Array Interview QuestionsFundamentalsString Class in Javatitle: String Class in JavaFundamentalsString Methodstitle: String MethodsFundamentalsString Practice Programstitle: String ProgramsFundamentalsImmutable Stringstitle: Immutable Strings in JavaFundamentalsStringBuffertitle: StringBuffer in Java