从 Fragment 到 MainActivity 的按钮 OnClick

Question

I have 3 Fragments inside my MainActivity and in one of my Fragments I have 3 ImageView and each of image view performs same action based on which ImageView was selected, now What I want to achieve is that instead of using OnClickListener for each of Views separately, call same method with switch-case or if-else inside. But the problem is those ImageViews inside fragment cannot call Functions implemented inside MainActivity. for instance. here's the code to understand what I want to say:

MAIN ACTIVITY

public void imageClicked(View v){
    if(v.getID() == findViewById(R.id.id_of_imageView_1).getID()){
        myTextView.setText("ImageView 1 is Clicked")
    }
    
    else if(v.getID() == findViewById(R.id.id_of_imageView_2).getID()){
        myTextView.setText("ImageView 2 is Clicked")
    }

    else if(v.getID() == findViewById(R.id.id_of_imageView_3).getID()){
        myTextView.setText("ImageView 3 is Clicked")
    }
}

XML (fragment_images.xml) WHERE IMAGES EXIST

<ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <ImageView
                android:id="@+id/id_of_imageView_1"
                android:layout_width="0dp"
                android:layout_height="100dp"
                android:layout_weight="1"
                android:src="@drawable/laptop" />

            <ImageView
                android:id="@+id/id_of_imageView_2"
                android:layout_width="0dp"
                android:layout_height="100dp"
                android:layout_weight="1"
                android:src="@drawable/memory" />

            <ImageView
                android:id="@+id/id_of_imageView_3"
                android:layout_width="0dp"
                android:layout_height="100dp"
                android:layout_weight="1"
                android:src="@drawable/screen" />

        </LinearLayout>
    </ScrollView>

XML (activity_main.xml) HERE I Link my Fragment and TextView

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">

     //CHANGE THIS TEXT VIEW WHEN IMAGE IS CLICKED
     <TextView
        android:id="@+id/myTextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:gravity="center_horizontal"
        android:text="Select Product"
        android:textSize="20sp"
        android:textStyle="bold" />

        <fragment
            android:id="@+id/fragment_1"
            android:name="com.salmanibrahim.calssifiedelectronics.ListFrag"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            tools:layout="@layout/fragment_list" />

        <fragment
            android:id="@+id/fragment_2"
            android:name="com.salmanibrahim.calssifiedelectronics.DetailFrag"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            tools:layout="@layout/fragment_detail" />

        //THIS IS THE FRAGMENT
        <fragment
            android:id="@+id/fragment_images"
            android:name="com.salmanibrahim.calssifiedelectronics.AddProduct"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            tools:layout="@layout/fragment_images" />
    </LinearLayout>

How do I call imageClicked() defined inside MainActivity using onClick on ImageView

Answer 1

In your fragment you can call imageClicked() in the MainActivity by using requireActivity() or getActivity() and do the necessary cast

In fragment:

public View onCreateView(...) {

    View view = inflater.inflate(R.layout.my_fragment_layout, container, false);
    MainActivity mActivity = (MainActivity) requireActivity();

    imageView1 = view.findViewById(...);
    imageView1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mActivity.imageClicked(imageView1);
        }
    });

    
...}

repeat the same for imageView2, 3

Also the condition in imageClicked() seems not right as you findViewById which will point to your MainActivity layout, not the fragment.

So you need to change this

if (v.getID() == findViewById(R.id.id_of_imageView_1).getID())

To

if (v.getID() == R.id.id_of_imageView_1)

And do the same for other images.

Answer 2

I understand what you trying to do but android:onClick parameter only links for the context declared in tools:context field on the parent tag of your layout file.

So it is not possible to reference your imageClicked() function found in your MainActivity from your fragment's ImageView because they are in different context. Check this for more info.

Answer 3

You are doing it in wrong way. You can do this instead.

imageView_1.setOnClickListener(this);

then implement activity from View.onClickListener

then get view by id on the method that's been implemented.

@Override
public void onClick(View view) {
    switch (view.getId()) {
        case R.id.id_of_imageView_1:
            // do your things here
            break;
        }
}