Android: error inflating extended class

Question 1

MyWebView class is internal of MainActivity class. Inflater does not see this class. Make your WebView in defferent .java file.

Also you can try to use that name in your layout file <com.example.test.MainActivity.MyWebView/>, but i'm not sure about it.

Question 2

Make sure you add all these constructors in your custom webview class.

    public CustomWebView(Context context) {
        super(context);
    }

    public CustomWebView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public CustomWebView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public CustomWebView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

And also don't forget to use this CustomWebView class in xml layout file with your complete package name.

 <com.kittykitty.meowmeow.CustomWebView
                android:id="@+id/my_webview"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                />

Question 3

// try this way
1. Custom WebView Class
public class MyWebView extends WebView {
    Context context;
    GestureDetector gd;
    OnPageChangleListener listener;
    private int currentPage=1;
    private int startPageIndex;
    private int lastPageIndex;

    public MyWebView(Context context) {
        super(context);
       init(context);
    }

    public MyWebView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public MyWebView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    private void init(Context context){
        this.context = context;
        gd = new GestureDetector(context, sogl);
    }


    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return (gd.onTouchEvent(event)
                || super.onTouchEvent(event));
    }

    public void setOnPageChangeListener(OnPageChangleListener listener){
        this.listener = listener;
    }

    public void setStartPageIndex(int startPageIndex){
        this.startPageIndex = startPageIndex;
    }

    public int getStartPageIndex(){
        currentPage = startPageIndex;
        return startPageIndex;
    }

    public int getLastPageIndex(){
        return lastPageIndex;
    }

    public void setLastPageIndex(int lastPageIndex){
        this.lastPageIndex = lastPageIndex;
    }
    GestureDetector.SimpleOnGestureListener sogl = new GestureDetector.SimpleOnGestureListener() {
        public boolean onDown(MotionEvent event) {
            return false;
        }
        public boolean onFling(MotionEvent event1, MotionEvent event2, float velocityX, float velocityY) {
            if (event1.getRawX() > event2.getRawX() && StrictMath.abs(event1.getRawY()-event2.getRawY())<100) {
                currentPage += 1;
                if (currentPage > lastPageIndex){
                    currentPage = lastPageIndex;
                    show_toast("Last Page");
                }else{
                    show_toast("swipe left");
                    listener.onPageChange(currentPage);
                }
            } else if(event1.getRawX() < event2.getRawX() && StrictMath.abs(event1.getRawY()-event2.getRawY())<100){
                currentPage -= 1;
                if (currentPage < startPageIndex) {
                    currentPage = startPageIndex;
                    show_toast("First Page");
                }else{
                    show_toast("swipe right");
                    listener.onPageChange(currentPage);
                }
            } else {
                return false;
            }
            return true;
        }
    };

    void show_toast(final String text) {
        Toast t = Toast.makeText(context, text, Toast.LENGTH_SHORT);
        t.show();
    }

}

2. Custom Interface for you Custom WebView page change listener.
public interface OnPageChangleListener {
    public void onPageChange(int pageNo);
}

3. Use Custom WebView in your Activity.
 MyWebView myWebView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        myWebView = (MyWebView) findViewById(R.id.myWebView);
        myWebView.getSettings().setUseWideViewPort(true);
        myWebView.getSettings().setSupportZoom(true);
        myWebView.getSettings().setBuiltInZoomControls(true);
        myWebView.setStartPageIndex(2);
        myWebView.setLastPageIndex(4);
        myWebView.setOnPageChangeListener(new OnPageChangleListener() {
            @Override
            public void onPageChange(int pageNo) {
                System.out.println(String.valueOf(pageNo));
                myWebView.loadUrl("file:///android_asset/" + pageNo + ".html");
            }
        });

        myWebView.loadUrl("file:///android_asset/" + myWebView.getStartPageIndex() + ".html");

}
4.main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <com.example.Demo.MyWebView
        android:id="@+id/myWebView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</LinearLayout>