Java String Methods — Java Technical Interview Questions & Answers

Java String Methods

Java String Methods

  • String Methods is about working with text in Java. Remember the base rule first: String is immutable. Compare content with equals, not ==.
  • For String Methods, common APIs from memory: length(), charAt(i), substring(start, end), contains, equalsIgnoreCase, toUpperCase. Index starts at 0.
  • If String Methods is StringBuilder/StringBuffer, you change text in place with append. If it is comparison, show == false and equals true for two new String("Hi").
  • For String Methods, say the output before you code. Off-by-one on substring is a common trap (end index is exclusive).
  • Let's take this on the board with one tiny Main class — no extra files. Java String Methods — shows length, substring, case change, and equalsIgnoreCase. Start from main, go line by line, and stop at each print. That output is the proof for String Methods.

Technical Interview Tip: == vs equals() on String is a classic trap.

Code Examples for Java String Methods

Example

// String methods
public class Main {
  public static void main(String[] args) {
    String s = "PrepPilot";
    System.out.println(s.length());
    System.out.println(s.substring(0, 4));
    System.out.println(s.toUpperCase());
    System.out.println("prep".equalsIgnoreCase("PREP"));
  }
}

Java String Methods — shows length, substring, case change, and equalsIgnoreCase.

How to Explain Java String Methods to an Interviewer

What is String Methods?

String Methods works with Java text. String itself is immutable. String Methods — compare content with equals, not ==. String Methods — length, charAt, substring. substring end index is exclusive.

Why do we use String Methods in Java?

Makes the program clearer or safer String Methods works with Java text. String itself is immutable.

Write one small example of String Methods.

Show syntax Say what prints

What mistake do beginners make with String Methods?

Only the name, no example String Methods — == compares references. User input almost never matches with ==.

Where is String Methods used in a real program?

Day-to-day Java code