Quick Answer

Resolve type mismatch errors.

Understanding the Issue

Occurs when assigning incompatible types without proper casting. Common with generics, collections, and primitive/object conversions.

The Problem

This code demonstrates the issue:

Java Error 
List<String> strings = new ArrayList<Object>(); // Error
int x = "123"; // Error

The Solution

Here's the corrected code:

Java Fixed 
// Proper generic assignment
List<String> strings = new ArrayList<>();

// Correct type conversion
int x = Integer.parseInt("123");

// Safe casting
Object obj = "hello";
if (obj instanceof String) {
    String s = (String) obj;
}

// Using pattern matching (Java 16+)
if (obj instanceof String s) {
    System.out.println(s.length());
}

Key Takeaways

Verify type compatibility and use proper conversions.