Norris Duncan:

The Android Studio debugger is giving me a Class Not Found exception whenever I try to run it. It seems like the crash is happening on line 38 - setContentView(R.layout.dataman_main); to set the main activity layout - which was working fine before. I'm an amateur developer and I've been stuck on this problem for 3 days - could anyone tell me what I am doing wrong?

Here's a copy of the debugger variables after the crash, with the "Exception" and "detailMessage" fields expanded:

Exception = {ClassNotFoundException@5326} 
 ex = {NoClassDefFoundError@5330} "java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack trace available"
 backtrace = {Object[38]@5331} 
 cause = null
 detailMessage = "android.widget.ViewStub"
  count = 46
  hash = 0
  shadow$_klass_ = {Class@3925} "class java.lang.String"
  shadow$_monitor_ = -1913475893
 stackTrace = {StackTraceElement[0]@5333} 
 suppressedExceptions = {Collections$EmptyList@5334}  size = 0
 shadow$_klass_ = {Class@4242} "class java.lang.ClassNotFoundException"
 shadow$_monitor_ = -2070025328
Variables debug info not available

Here's what my main activity looks like:

package norrisduncan.dataman;

import android.content.Context;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.PointF;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.WindowManager;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.view.ViewStub;

import java.lang.reflect.InvocationTargetException;

import norrisduncan.dataman.adapter.MainPagerAdapter;

/**
 * Created by norri on 12/13/2017.
 */


public class DataMan_Main extends AppCompatActivity {

PointF startPoint = new PointF(0,0);
PointF endPoint = new PointF(0,0);

private norrisduncan.dataman.UsableScreenSizeLineView UsableScreenSizeLineView;

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

    //FINDING THE SIZE OF THE USABLE SCREEN SPACE SO THAT UI ELEMENTS CAN SCALE TO IT
    DisplayMetrics displayMetrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
    int usableScreenWidth = displayMetrics.widthPixels;
    int usableScreenHeight = displayMetrics.heightPixels;

    //ASSOCIATES UI JAVA IMAGEVIEW FIELDS WITH THEIR XML IMAGEVIEWS
    ImageView actionDrawerPullTab = findViewById(R.id.actionDrawerPullTabImageViewXML);

    UsableScreenSizeLineView = findViewById(R.id.usable_screen_size_line_view);
    UsableScreenSizeLineView.setStartPoint(startPoint);
    endPoint.set(usableScreenWidth,usableScreenHeight);
    UsableScreenSizeLineView.setEndPoint(endPoint);
    UsableScreenSizeLineView.draw();

    //SETS THE PAINT COLOR AND SIZE FOR THE TEST LINE THAT TELLS ME HOW BIG THE USABLE SCREEN SIZE IS
    Paint screenSizeTestLinePaint = new Paint();
    screenSizeTestLinePaint.setColor(Color.BLACK);
    screenSizeTestLinePaint.setStrokeWidth(1f);

    //SETS THE PULL TAB IMAGEVIEW SIZES ACCORDING TO SCREEN SIZE
    RelativeLayout.LayoutParams actionDrawerPullTabParams = new RelativeLayout.LayoutParams(usableScreenHeight / 3, usableScreenHeight / 6);
    actionDrawerPullTabParams.leftMargin = 0 - usableScreenHeight * 3 / 18;
    actionDrawerPullTabParams.topMargin = 0;
    actionDrawerPullTab.setLayoutParams(actionDrawerPullTabParams);

    //SETS THE VIEWPAGER AND PAGERADAPTER
    ViewPager viewPager = findViewById(R.id.view_pager);
    MainPagerAdapter mainPagerAdapter = new MainPagerAdapter(getSupportFragmentManager());
    viewPager.setAdapter(mainPagerAdapter);

}

//FINDS THE FULL SCREEN SIZE USING EITHER display.getRealSize() OR ELSE IT DOES SOME ?MAGIC? TO ?.INVOKE?
//(NEVER HEARD OF THIS) getRawHeight()/getRawWidth() ON THE DEFAULT DISPLAY
public static Point getScreenRealSize(Context context) {
    WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    Display display = windowManager.getDefaultDisplay();
    Point size = new Point();

    if (Build.VERSION.SDK_INT >= 17) {
        display.getRealSize(size);
    } else if (Build.VERSION.SDK_INT >= 14) {
        try {
            size.x = (Integer) Display.class.getMethod("getRawWidth").invoke(display);
            size.y = (Integer) Display.class.getMethod("getRawHeight").invoke(display);
        } catch (IllegalAccessException e) {
        } catch (InvocationTargetException e) {
        } catch (NoSuchMethodException e) {
        }
    }
    return size;
}

public static Point getUsableScreenSize(Context context) {
    WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    Display display = windowManager.getDefaultDisplay();
    Point size = new Point();
    display.getSize(size);
    return size;
}

}

The layout file dataman_main.xml that the setContentView() method is supposed to load:

    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    >

        android:id="@+id/baselayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/paper" />

        android:id="@+id/usable_screen_size_line_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    android:id="@+id/actionDrawerPullTabImageViewXML"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/actions_drawer_pull_tab_textured_662x331x441ppi"
    />

            android:id="@+id/view_pager"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="48dp"
        android:text="@string/layout_fragment_1_title" />

The manifest:

    package="norrisduncan.dataman">

            android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

                    android:screenOrientation="portrait"
            android:theme="@style/FullScreenTheme">

And if it will help, I can provide my other classes, too - there are 6 of them, but I don't think any of them even get called before the crash happens. What the heck am I doing wrong to this poor program???