Insert ImageView dynamically using Java code

package com.example.androidinsertimages;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;

public class MainActivity extends Activity {
 
 Button addinHorizontalScrollView, addinScrollView;
 LinearLayout inHorizontalScrollView, inScrollView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        inHorizontalScrollView = (LinearLayout)findViewById(R.id.inhorizontalscrollview);
        inScrollView = (LinearLayout)findViewById(R.id.inscrollview);
        
        addinHorizontalScrollView = (Button)findViewById(R.id.addinhorizontalscrollview);
        addinHorizontalScrollView.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View arg0) {
    addImageView(inHorizontalScrollView);
   }});
        
        addinScrollView = (Button)findViewById(R.id.addinscrollview);
        addinScrollView.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View arg0) {
    addImageView(inScrollView);
   }});
        
    }
    
    private void addImageView(LinearLayout layout){
     ImageView imageView = new ImageView(this);
     imageView.setImageResource(R.drawable.ic_launcher);
     layout.addView(imageView);
    }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world"
        tools:context=".MainActivity" />
    
    <Button
        android:id="@+id/addinhorizontalscrollview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Add in HorizontalScrollView"/>
    <HorizontalScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <LinearLayout
            android:id="@+id/inhorizontalscrollview"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
        </LinearLayout>
    </HorizontalScrollView>
    
    <Button
        android:id="@+id/addinscrollview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Add in ScrollView"/>
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <LinearLayout
            android:id="@+id/inscrollview"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical">
        </LinearLayout>
    </ScrollView>

</LinearLayout>