Understanding Ambiguity in Java 8 Method Overloading

What causes method ambiguity in Java 8, and how can I resolve it?

public void exampleMethod(String s) { /*...*/ }
public void exampleMethod(Object o) { /*...*/ }

exampleMethod(null); // Causes ambiguity

In Java 8, method overloading can lead to ambiguity when the compiler cannot determine which method to call. This typically occurs when you invoke a method with a parameter that could match multiple overloaded versions of that method.

public void exampleMethod(String s) {
    // implementation
}

public void exampleMethod(Object o) {
    // implementation
}

// To avoid ambiguity, specify the type explicitly:
exampleMethod((String) null); // Call to String version

Causes

• Using `null` as an argument for overloaded methods where parameter types can accept `null` for multiple signatures.
• Having overloaded methods that differ only by their parameter types but not by the number of parameters or their order.
• Inconsistent type inference when using wildcard types or generic types.

Solutions

• Avoid using null as an argument by explicitly casting it to the desired type (e.g., (String) null or (Object) null).
• Refactor the method names if possible to ensure clearer method calls.
• Utilize method overloading techniques that rely on different parameter counts or distinct types.

Mistake: Calling overloaded methods with null parameters leading to ambiguity.

Solution: Always specify the type when calling overloaded methods that could result in ambiguity.

Mistake: Not defining overloaded methods clearly enough to differentiate them.

Solution: Ensure overloaded methods have either different numbers of parameters or distinctly different types.