Question

Here’s the implementation of java.lang.reflect.Method.equals(Object obj) as of Java 7:

/**
 * Compares this {@code Method} against the specified object.  Returns
 * true if the objects are the same.  Two {@code Methods} are the same if
 * they were declared by the same class and have the same name
 * and formal parameter types and return type.
 */
public boolean equals(Object obj) {
    if (obj != null && obj instanceof Method) {
        Method other = (Method)obj;
        if ((getDeclaringClass() == other.getDeclaringClass())
            && (getName() == other.getName())) {
            if (!returnType.equals(other.getReturnType()))
                return false;
            /* Avoid unnecessary cloning */
            Class<?>[] params1 = parameterTypes;
            Class<?>[] params2 = other.parameterTypes;
            if (params1.length == params2.length) {
                for (int i = 0; i < params1.length; i++) {
                    if (params1[i] != params2[i])
                        return false;
                }
                return true;
            }
        }
    }
    return false;
}

The most interesting part here is comparison of method names: getName() == other.getName(). Those return java.lang.String and hence a natural question is whether it’s valid to compare them by references (==). While this code obviously works the question is whether it can be a source of bugs in reflection-oriented frameworks. What do you think?

Answer 1

One thing interesting when you look directly on name attribute of Method class.

 // This is guaranteed to be interned by the VM in the 1.4
// reflection implementation
private String              name;

So by interning String you can directly compare reference.

More on String.intern()