Quick Answer

Handle invalid type casting.

Understanding the Issue

Occurs when trying to cast an object to a subclass of which it is not an instance. Always check with instanceof before casting.

The Problem

This code demonstrates the issue:

Java Error 
Object obj = "hello";
Integer num = (Integer) obj;  // Throws

The Solution

Here's the corrected code:

Java Fixed 
// Safe casting
if (obj instanceof Integer) {
    num = (Integer) obj;
} else {
    // Handle incompatible type
}

// With pattern matching (Java 16+)
if (obj instanceof Integer i) {
    System.out.println(i + 1);
}

Key Takeaways

Always verify types before casting.