The ICSE Class 10 Computer Applications syllabus focuses heavily on Object-Oriented Programming (OOP) in Java using the BlueJ environment. The main topics covered are: 

ICSE Class 10 Computer Applications Syllabus (BlueJ) 

The syllabus is generally divided into two sections for the board exam: Theory and Practical (Internal Assessment). 

Key Theoretical Concepts:

• Object-Oriented Programming (OOP) Concepts: Understanding principles like Encapsulation, Abstraction, Polymorphism (specifically method overloading), and Inheritance (only definition and examples for Class 9/10, not advanced implementation).
• Classes and Objects: The class as a basis of computation, creating objects as instances of a class, member variables (attributes), and member methods (behavior).
• Data Types and Operators: Revision of primitive and composite data types, variable declarations, and various operators in Java.
• Input in Java: Using the Scanner class for user input of various data types.
• User-defined Methods: Need for methods, syntax, forms of methods (pure/impure, static/non-static), method overloading, and parameter passing (call by value/reference).
• Constructors: Definition, characteristics, types (default, parameterized), and constructor overloading.
• Library Classes: Introduction to wrapper classes (autoboxing/unboxing), and their methods for type conversion and character manipulation, e.g., Integer.parseInt(), Character.isDigit() etc..
• Conditional and Iterative Constructs: Revision of if, if-else, switch, while, do-while, and for loops, including nested loops, break, and continue statements.
• Arrays: Definition, declaration, initialization, and usage of single-dimensional and double-dimensional arrays. This includes sorting (Bubble and Selection sort) and searching (Linear and Binary search) techniques for single-dimensional arrays, and matrix operations (sum of rows/columns/diagonals) for double-dimensional arrays.
• String Handling: The String class and its various methods like length(), charAt(), indexOf(), substring(), equals(), compareTo(), toLowerCase(), toUpperCase(), etc., and programs based on these methods.