ICSE Class 10 Java | String Handling Lecture 4: String Comparison (equals vs ==)

Описание: Master ICSE Java: String Handling Output-Based Exercises (Lecture 4)

In Lecture 4 of our ICSE Class 10 Computer Applications series (Syllabus 2025-2026), we go through a comprehensive revision of all String methods. Instead of just theory, we solve 15+ Board-style output questions to ensure you are ready for Section A of your exam.

Learn how to handle tricky scenarios like integer division inside charAt(), nested methods, and the exact difference between + and concat().

📌 What you will master in this session:

String Indices: How to accurately map positions in strings like "Computer" and "Applications."

Mathematical Strings: Handling a.charAt(9/2) and understanding integer division.

Nested Methods: Solving from right-to-left in expressions like b.charAt(a.indexOf('m')).

ASCII Math: Calculating the result for compareTo() without memorizing the whole table.

Math + Strings: Why Math.pow() returns a .0 (double) even when working with String indices.

Exam Technique: How to show your "Working" vs. your "Final Output" to secure full marks.

🕒 Timestamps:
00:00 Introduction & Exercise Overview
02:42 Exercise 1: Solving String Expressions (A to O)
02:50 (A) a + b: The join operator logic
03:52 (B) a.length() + b.length(): Integer addition
04:52 (C) a.charAt(9/2): Tricky integer division index
06:27 (D) Substring combination: Creating "complications"
08:14 (E) b.indexOf('i'): Finding the first occurrence
08:52 (F) b.indexOf("TION"): Searching for substrings
09:31 (G) a.indexOf('z'): Why it returns -1
10:03 (H) b.lastIndexOf('i'): Right-to-left searching
10:55 (I) a.toUpperCase()
11:19 (J) a.startsWith("com"): Boolean return values
12:03 (L) a.equals(b)
12:21 (M) a.compareTo(b): Deep dive into ASCII subtraction
14:17 (N) a.concat(b) vs the plus operator
14:54 (O) a.replace(): Character swapping logic
15:54 Exercise 2: Advanced & Wrapper Class Methods
16:56 (A) toLowerCase() with alphanumeric strings
17:36 (B) Character.isLetter(): Using Wrapper Classes
18:21 (C) indexof() for the word "cat" in "application"
19:04 (D) Nested Methods: Solving from right-to-left
20:22 (E) Math.pow() + String Index: The importance of .0 (Double)
21:49 Pro Exam Tip: Showing "Working" vs "Final Output"
24:24 Conclusion & Practice Advice

💡 Pro-Tip for Students: When solving nested methods like b.charAt(a.indexOf('m')), always solve the innermost bracket first!

🔔 Join the Community! Practice is the key to a 100/100 in Computer Applications. If you had any doubts during the exercise, leave a comment below!

#ICSEClass10 #JavaProgramming #ComputerApplications #ICSE2026 #BlueJ #StringHandling #OutputBasedQuestions #JavaExercises #SaritaAswal #BoardExamPrep