Using Kotlin Library in java

Question

I am trying to use a GitHub library (MeowBottomNavigation)in Android Studio.But its written in kotlin and i cant use the listeners in it. The only thing which is given is this

bottomNavigation.setOnShowListener {
}

bottomNavigation.setOnClickMenuListener {
}

the suggestions shows to use

(Function1)

i am not sure as to how to implement this in java . Any help will be appreciated.

I am familiar with java but the library is written in Kotlin. Is there any way to use these listeners in java?

bottomNavigation.setOnClickMenuListener(new 
Function1<MeowBottomNavigation.Model, Unit>() {
        @Override
        public Unit invoke(MeowBottomNavigation.Model p1) {
            int i = p1.getId();
            switch (i){
                case 4:
                    Toast.makeText(UserMainActivity.this, i, Toast.LENGTH_SHORT).show();
                    break;
                case  1:
                    Toast.makeText(UserMainActivity.this, i, Toast.LENGTH_SHORT).show();
                    break;
                case 2:
                    Toast.makeText(UserMainActivity.this, i, Toast.LENGTH_SHORT).show();
                    break;
                case 3:
                    Toast.makeText(UserMainActivity.this, i, Toast.LENGTH_SHORT).show();
                    break;
            }
            return Unit.INSTANCE;
        }
    });

Sounds very much alike https://stackoverflow.com/q/44301301/4636715 except `setOnClickListener` is mentioned there. May give you a clue. — vahdet, Mar 29 '19 at 07:23
I am not familiar with kotlin i want to implement it in java.The problem is the listener has no body and suggestions shows ( Function1 super Model, Unit> ) i am not sure how to use this in java. — Hemu Sharma, Mar 29 '19 at 07:27
This link might be helpful: [How to convert a kotlin source file to a java source file](https://stackoverflow.com/questions/34957430/how-to-convert-a-kotlin-source-file-to-a-java-source-file) — lambda, Mar 29 '19 at 07:46

score 4 · Accepted Answer · answered Mar 29 '19 at 09:13

4

Function0, Function1, Function2, ... FunctionN are higher-order functions in kotlin.

After converting to java, your click listeners become something like below.

// Set Menu Click Listener 
bottomNavigation.setOnClickMenuListener(new Function1<MeowBottomNavigation.Model, Unit>() {
        @Override
        public Unit invoke(MeowBottomNavigation.Model p1) {
            return Unit.INSTANCE;
        }
    });

// Set Menu Show listener
bottomNavigation.setOnShowListener(new Function1<MeowBottomNavigation.Model, Unit>() {
        @Override
        public Unit invoke(MeowBottomNavigation.Model s) {
            return Unit.INSTANCE;
        }
    });

answered Mar 29 '19 at 09:13

Srikar Reddy

3,180
4
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but how do i access the click event here. I tried using int i = p1.getId(); and then tried a toast to display the value.But its showing error android.content.res.Resources$NotFoundException: String resource ID #0x4 – Hemu Sharma Mar 29 '19 at 09:41
Please see above I have updated the code please tell me where i am wrong. – Hemu Sharma Mar 29 '19 at 09:43
also, you should add kotlin dependencies to your java app otherwise you will have a problem that says . you can do it by creating an extra activity with kotlin codebase and Android Studio will handle gradle changes automatically. You can delete the extra activity after that :-) – Koorosh Aug 21 '19 at 07:28

score 0 · Answer 2 · answered Mar 29 '19 at 07:57

0

something like This::

bottomNavigation.setOnShowListener( new IBottomNavigationListener(Model model)
{


} );

answered Mar 29 '19 at 07:57

cannot resolve symbol IBottomNavigationListener & Model – Hemu Sharma Mar 29 '19 at 08:34

score 0 · Answer 3 · answered Jan 14 '21 at 23:41

if you are using fragments

//1.-declare fragments globally in your activity

private HomeFragment homeFragment = new HomeFragment();

//2.- declare a method to switch between fragments

public void loadFragment(Fragment fragment){
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.yourFragmentContainer,fragment);
        transaction.commit();
    }

//3.- in the Set Menu Click/show Listener call the fragment to show

// Set Menu Click Listener







      bottomNavigation.setOnClickMenuListener(new Function1<MeowBottomNavigation.Model, Unit>() {
                @Override
                public Unit invoke(MeowBottomNavigation.Model model) {
                    int i = model.getId();
                    switch (i){
                        case  1:
                            loadFragment(homeFragment);
                            break;
                            //...other cases
    
                    }
                    return Unit.INSTANCE;
                }
            });
        
        // Set Menu Show listener
        bottomNavigation.setOnShowListener(new Function1<MeowBottomNavigation.Model, Unit>() {
                @Override
                public Unit invoke(MeowBottomNavigation.Model model) {
                    int i = model.getId();
                    switch (i){
                        case  1:
                            loadFragment(homeFragment);
                            break;
                            //...other cases
                    }
                    return Unit.INSTANCE;
                }
            });

Using Kotlin Library in java

3 Answers3

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