Method overloading in Java is the ability to define multiple methods in a class with the same name but different parameters. However, changing only the return type of a method is not sufficient to distinguish overloaded methods. Here’s why method overloading based solely on return type is not allowed in Java:

1. Ambiguity: If method overloading were allowed based on return type, it could lead to ambiguity in resolving which method should be invoked. Consider a scenario where two methods have the same name, same parameters, but different return types. When a method call is made, the compiler would have difficulty determining which method to choose based on the return type alone, resulting in ambiguity.
2. Compile-Time Resolution: In Java, method overloading is resolved at compile time based on the number, type, and order of the method parameters. The return type is not considered during the method resolution process. Changing only the return type would not provide sufficient information for the compiler to determine which overloaded method should be invoked.
3. Java’s Type Promotion Rules: Java’s type promotion rules ensure that a method call resolves to the most specific overloaded method available. These rules are based on the method’s parameter types and do not consider the return type. If return type overloading were allowed, it would conflict with the existing type promotion rules and introduce inconsistencies in the method resolution process.

To achieve method overloading in Java, you need to differentiate the methods based on their parameter types, their number, or the order of the parameters. This allows the compiler to determine the appropriate method to invoke based on the provided arguments, avoiding ambiguity and ensuring predictable behavior.