Access parameter from anonymous class

Question

I have a (pedantic) Java question: I want to create an anonymous class in a method and assign a method parameter to a member with the same name. The code below does not work as it assigns the member to itself.

class TestClass {
    String id;
}

TestClass createTestClass(final String id) {
    return new TestClass() {{
        this.id = id; // self assignment of member
    }};
}

Beside the obvious method to rename the id parameter, is there any other way to access it? Thx

do you want an anonymous class just for the assignment of the `id` field? — wero, Oct 06 '15 at 12:11
@wero I think this is just a simplified example of the general concept :D — Sebastian S, Oct 06 '15 at 12:12
I don't quite understand why you need an anonymous class here? — TheLostMind, Oct 06 '15 at 12:17
It's an simplified example. id is protected in a different package and not accessible from the outside. — redspider, Oct 06 '15 at 12:23
Duplicate of [this question](http://stackoverflow.com/questions/19155269/access-shadowed-variable-from-anonymous-class)? — Keppil, Oct 06 '15 at 12:34
Or [this one](http://stackoverflow.com/questions/10144789/can-final-parameters-be-qualified-in-some-way-to-resolve-naming-conflicts-with-a/10145300#10145300) — Alex, Oct 06 '15 at 12:37

score 1 · Answer 1 · answered Oct 06 '15 at 12:14

You can avoid the anonymous class

TestClass createTestClass(final String id) {
     TestClass testClass = new TestClass();
     testClass.id = id;
     return testClass;
}

or rename the parameter

TestClass createTestClass(final String theId) {
    return new TestClass() {{
        this.id = theId; 
    }};
}

or drop the factory method all together by introducing a constructor parameter:

class TestClass {
    public TestClass(String id) { this.id = id; }
    String id;
}

Arpit Aggarwal · Answer 2 · 2015-10-06T13:14:24.970

Offtopic, Java 8 Snippet to achieve the same:

Function<String, TestClass> createTestClass = TestClass::new;

Usage:

final class TestClass {
    private final String id;

    public TestClass(String id) {
        this.id = id;
    }

    public String getId() {
        return id;
    }
};

public class AnyClass {
    static Function<String, TestClass> createTestClass = TestClass::new;

    public static void main(String[] args) {
        TestClass testclass = createTestClass.apply("hello");
        System.out.println(testclass.getId());
    }
}

Access parameter from anonymous class

2 Answers2