Android template error Transformation.map

Question

I've tryied to use a template (tabbed view activity) in a new project (java).. but it won't run (no code modifications). Version 2.1.2 on Win 11 error given:

C:\Progetti\Android\Test\app\src\main\java\it\gattoneroph\test\ui\main\PageViewModel.java:12: error: method map in class Transformations cannot be applied to given types; private LiveData mText = Transformations.map(mIndex, new Function<Integer, String>() { ^ required: LiveData,Function1<X,Y> found: MutableLiveData,<anonymous Function<Integer,String>> reason: cannot infer type-variable(s) X,Y (argument mismatch; <anonymous Function<Integer,String>> cannot be converted to Function1<X,Y>) where X,Y are type-variables: X extends Object declared in method <X,Y>map(LiveData,Function1<X,Y>) Y extends Object declared in method <X,Y>map(LiveData,Function1<X,Y>)

class

public class PageViewModel extends ViewModel {

    private MutableLiveData<Integer> mIndex = new MutableLiveData<>();
    private LiveData<String> mText = Transformations.map(mIndex, new Function<Integer, String>() {
        @Override
        public String apply(Integer input) {
            return "Hello world from section: " + input;
        }
    });

    public void setIndex(int index) {
        mIndex.setValue(index);
    }

    public LiveData<String> getText() {
        return mText;
    }
}

why? I've no idea why this template seems to be broken.

score 2 · Accepted Answer · answered Apr 18 '23 at 19:26

2

As explained in this known issue, the template is generating the code expected by earlier versions of the Lifecycle library. However, that code changed in Lifecycle 2.6.0.

As your error message says, replace new Function with new Function1, which is the expected class when using Lifecycle 2.6.0 or higher.

answered Apr 18 '23 at 19:26

ianhanniballake

191,609
30
470
443

thank you (I'm only a beginner so .. i get stucked by simple problems) – Denis De Pauli Apr 18 '23 at 19:55

score 0 · Answer 2 · answered Jun 05 '23 at 19:59

0

I converted or replace the

Transformations.map(mIndex, new Function<Integer, String>() {

to lambda.

Since changing it to new Function1 doesn't work for me.

answered Jun 05 '23 at 19:59

Katufo Prem

45
6

Ahmed Nafea · Answer 3 · 2023-06-18T12:09:15.960

0

1- Replace Function to Function1 like following

new Function<Integer, String>(){}

to

new Function1<Integer, String>()

2- implement the required method

@Override
        public String invoke(Integer input) {
            return "Hello world from section: " + input;
        }

thanks it is working with me :)

edited Jun 18 '23 at 12:09

answered Jun 15 '23 at 13:22

Ahmed Nafea

56
5

Android template error Transformation.map

3 Answers3