Adding an instance of my created class to xml file

Question

i have a DrawingView class, that class creates an drawing view for. Code of that class you can see below. But the problem occurs when i want to create an instance of that class in xml file. What im doing wrong?

code of xml :

<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:background="#FFCCCCCC"
android:orientation="vertical"
tools:context=".MainActivity" >

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="50dp"
    android:layout_gravity="center"
    android:orientation="horizontal" >

    <ImageButton
        android:id="@+id/new_btn"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:contentDescription="@string/start_new"
        android:src="@drawable/new_pic" />

    <ImageButton
        android:id="@+id/draw_btn"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:contentDescription="@string/brush"
        android:src="@drawable/brush" />

    <ImageButton
        android:id="@+id/erase_btn"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:contentDescription="@string/erase"
        android:src="@drawable/eraser" />

    <ImageButton
        android:id="@+id/save_btn"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:contentDescription="@string/save"
        android:src="@drawable/save" />
</LinearLayout>

<com.example.drawingapp.DrawingView
    android:id="@+id/drawing"
    android:layout_width="fill_parent"
    android:layout_height="0dp"
    android:layout_marginBottom="3dp"
    android:layout_marginLeft="5dp"
    android:layout_marginRight="5dp"
    android:layout_marginTop="3dp"
    android:layout_weight="1"
    android:background="#FFFFFFFF" />

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:orientation="vertical" >

    <!-- Top Row -->

    <LinearLayout
        android:id="@+id/paint_colors"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <ImageButton
            android:layout_width="@dimen/large_brush"
            android:layout_height="@dimen/large_brush"
            android:layout_margin="2dp"
            android:background="#FF660000"
            android:contentDescription="@string/paint"
            android:onClick="paintClicked"
            android:src="@drawable/paint"
            android:tag="#FF660000" />

        <ImageButton
            android:layout_width="@dimen/large_brush"
            android:layout_height="@dimen/large_brush"
            android:layout_margin="2dp"
            android:background="#FFFF0000"
            android:contentDescription="@string/paint"
            android:onClick="paintClicked"
            android:src="@drawable/paint"
            android:tag="#FFFF0000" />

        <ImageButton
            android:layout_width="@dimen/large_brush"
            android:layout_height="@dimen/large_brush"
            android:layout_margin="2dp"
            android:background="#FFFF6600"
            android:contentDescription="@string/paint"
            android:onClick="paintClicked"
            android:src="@drawable/paint"
            android:tag="#FFFF6600" />

        <ImageButton
            android:layout_width="@dimen/large_brush"
            android:layout_height="@dimen/large_brush"
            android:layout_margin="2dp"
            android:background="#FFFFCC00"
            android:contentDescription="@string/paint"
            android:onClick="paintClicked"
            android:src="@drawable/paint"
            android:tag="#FFFFCC00" />

        <ImageButton
            android:layout_width="@dimen/large_brush"
            android:layout_height="@dimen/large_brush"
            android:layout_margin="2dp"
            android:background="#FF009900"
            android:contentDescription="@string/paint"
            android:onClick="paintClicked"
            android:src="@drawable/paint"
            android:tag="#FF009900" />

        <ImageButton
            android:layout_width="@dimen/large_brush"
            android:layout_height="@dimen/large_brush"
            android:layout_margin="2dp"
            android:background="#FF009999"
            android:contentDescription="@string/paint"
            android:onClick="paintClicked"
            android:src="@drawable/paint"
            android:tag="#FF009999" />
    </LinearLayout>
    <!-- Bottom Row -->

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

        <ImageButton
            android:layout_width="@dimen/large_brush"
            android:layout_height="@dimen/large_brush"
            android:layout_margin="2dp"
            android:background="#FF0000FF"
            android:contentDescription="@string/paint"
            android:onClick="paintClicked"
            android:src="@drawable/paint"
            android:tag="#FF0000FF" />

        <ImageButton
            android:layout_width="@dimen/large_brush"
            android:layout_height="@dimen/large_brush"
                android:layout_margin="2dp"
                android:background="#FF990099"
                android:contentDescription="@string/paint"
                android:onClick="paintClicked"
                android:src="@drawable/paint"
                android:tag="#FF990099" />

            <ImageButton
                android:layout_width="@dimen/large_brush"
                android:layout_height="@dimen/large_brush"
                android:layout_margin="2dp"
                android:background="#FFFF6666"
                android:contentDescription="@string/paint"
                android:onClick="paintClicked"
                android:src="@drawable/paint"
                android:tag="#FFFF6666" />

            <ImageButton
                android:layout_width="@dimen/large_brush"
                android:layout_height="@dimen/large_brush"
                android:layout_margin="2dp"
                android:background="#FFFFFFFF"
                android:contentDescription="@string/paint"
                android:onClick="paintClicked"
                android:src="@drawable/paint"
                android:tag="#FFFFFFFF" />

            <ImageButton
                android:layout_width="@dimen/large_brush"
                android:layout_height="@dimen/large_brush"
                android:layout_margin="2dp"
                android:background="#FF787878"
                android:contentDescription="@string/paint"
                android:onClick="paintClicked"
                android:src="@drawable/paint"
                android:tag="#FF787878" />

            <ImageButton
                android:layout_width="@dimen/large_brush"
                android:layout_height="@dimen/large_brush"
                android:layout_margin="2dp"
                android:background="#FF000000"
                android:contentDescription="@string/paint"
                android:onClick="paintClicked"
                android:src="@drawable/paint"
                android:tag="#FF000000" />
        </LinearLayout>
    </LinearLayout>

</LinearLayout>

Code of DrawingView class :

package com.example.drawingapp;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.util.TypedValue;

public class DrawingView extends View {
    // drawing path
    private Path drawPath;
    // drawing and canvas paint
    private Paint drawPaint, canvasPaint;
    // initial color
    private int paintColor = 0xFF660000;
    // canvas
    private Canvas drawCanvas;
    // canvas bitmap
    private Bitmap canvasBitmap;
    private ImageButton currPaint;
    private DrawingView drawView;
    private boolean erase = false;

    private float brushSize, lastBrushSize;

    public DrawingView(Context context, AttributeSet attrs) {
        super(context, attrs);
        setupDrawing();
        drawView = (DrawingView) findViewById(R.id.drawing);
        LinearLayout paintLayout = (LinearLayout) findViewById(R.id.paint_colors);
        currPaint = (ImageButton) paintLayout.getChildAt(0);
        currPaint.setImageDrawable(getResources().getDrawable(
                R.drawable.paint_pressed));

    }

    private void setupDrawing() {
        // get drawing area setup for interacion
        drawPath = new Path();
        drawPaint = new Paint();

        drawPaint.setColor(paintColor);
        drawPaint.setAntiAlias(true);
        drawPaint.setStrokeWidth(20);
        drawPaint.setStyle(Paint.Style.STROKE);
        drawPaint.setStrokeJoin(Paint.Join.ROUND);
        drawPaint.setStrokeCap(Paint.Cap.ROUND);
        canvasPaint = new Paint(Paint.DITHER_FLAG);
        brushSize = getResources().getInteger(R.integer.medium_size);
        lastBrushSize = brushSize;
        drawPaint.setStrokeWidth(brushSize);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        // TODO Auto-generated method stub
        super.onSizeChanged(w, h, oldw, oldh);
        canvasBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        drawCanvas = new Canvas(canvasBitmap);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);
        canvas.drawPath(drawPath, drawPaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // TODO Auto-generated method stub
        float touchX = event.getX();
        float touchY = event.getY();
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            drawPath.moveTo(touchX, touchY);
            break;
        case MotionEvent.ACTION_MOVE:
            drawPath.lineTo(touchX, touchY);
            break;
        case MotionEvent.ACTION_UP:
            drawCanvas.drawPath(drawPath, drawPaint);
            drawPath.reset();
            break;
        default:
            return false;
        }
        invalidate();
        return true;
    }

    public void paintClicked(View view) {
        if (view != currPaint) {
            // update color
            drawView.setErase(false);
            drawView.setBrushSize(drawView.getLastBrushSize());
            ImageButton imgView = (ImageButton) view;
            String color = view.getTag().toString();
            drawView.setColor(color);
            imgView.setImageDrawable(getResources().getDrawable(
                    R.drawable.paint_pressed));
            currPaint.setImageDrawable(getResources().getDrawable(
                    R.drawable.paint));
            currPaint = (ImageButton) view;
        }
    }

    public void setColor(String newColor) {
        // set color
        invalidate();
        paintColor = Color.parseColor(newColor);
        drawPaint.setColor(paintColor);

    }

    public void setBrushSize(float newSize) {
        // update size
        float pixelAmount = TypedValue.applyDimension(
                TypedValue.COMPLEX_UNIT_DIP, newSize, getResources()
                        .getDisplayMetrics());
        brushSize = pixelAmount;
        drawPaint.setStrokeWidth(brushSize);
    }

    public void setLastBrushSize(float lastSize) {
        lastBrushSize = lastSize;
    }

    public float getLastBrushSize() {
        return lastBrushSize;
    }

    public void setErase(boolean isErase) {
        // set erase true or false
        erase = isErase;
        if (erase)
            drawPaint
                    .setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
        else
            drawPaint.setXfermode(null);
    }

    public void startNew() {
        drawCanvas.drawColor(0, PorterDuff.Mode.CLEAR);
        invalidate();
    }
}

Logcat shows me the error:

   10-16 11:57:56.171: E/AndroidRuntime(17594): FATAL EXCEPTION: main
10-16 11:57:56.171: E/AndroidRuntime(17594): Process: com.example.drawingapp, PID: 17594
10-16 11:57:56.171: E/AndroidRuntime(17594): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.drawingapp/com.example.drawingapp.MainActivity}: android.view.InflateException: Binary XML file line #44: Error inflating class com.example.drawingapp.DrawingView.java
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.os.Handler.dispatchMessage(Handler.java:102)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.os.Looper.loop(Looper.java:136)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.ActivityThread.main(ActivityThread.java:5001)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at java.lang.reflect.Method.invokeNative(Native Method)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at java.lang.reflect.Method.invoke(Method.java:515)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at dalvik.system.NativeStart.main(Native Method)
10-16 11:57:56.171: E/AndroidRuntime(17594): Caused by: android.view.InflateException: Binary XML file line #44: Error inflating class com.example.drawingapp.DrawingView.java
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:707)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.Activity.setContentView(Activity.java:1929)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.support.v7.app.ActionBarActivity.superSetContentView(ActionBarActivity.java:217)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.support.v7.app.ActionBarActivityDelegateICS.setContentView(ActionBarActivityDelegateICS.java:110)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:77)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at com.example.drawingapp.MainActivity.onCreate(MainActivity.java:28)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.Activity.performCreate(Activity.java:5231)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
10-16 11:57:56.171: E/AndroidRuntime(17594):    ... 11 more
10-16 11:57:56.171: E/AndroidRuntime(17594): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.drawingapp.DrawingView.java" on path: DexPathList[[zip file "/data/app/com.example.drawingapp-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.drawingapp-1, /vendor/lib, /system/lib]]
10-16 11:57:56.171: E/AndroidRuntime(17594):    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.view.LayoutInflater.createView(LayoutInflater.java:559)
10-16 11:57:56.171: E/AndroidRuntime(17594):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:696)
10-16 11:57:56.171: E/AndroidRuntime(17594):    ... 24 more

Ok, the text "Error inflating class com.example.drawingapp.DrawingView " states there is an error in Your constructor, or Your setters. You could place a breakpoint on all of them and see how it works — maslan
– maslan, Commented Oct 16, 2014 at 9:22
the problem is on currPaint = (ImageButton) paintLayout.getChildAt(0); — Lauris01
– Lauris01, Commented Oct 16, 2014 at 9:31

Denley Bihari · Accepted Answer · 2014-10-16 09:21:23Z

0

You'll probably be able to see a NullPointerException in the LogCat too.

findViewById(R.id.paint_colors) will be returning null because there is no child view with that ID. In fact, a View class cannot have any child views.

I suspect you mean to be inflating a layout into the view, in which case you should extend ViewGroup instead of View and include the following lines underneath super(context, attrs):

LayoutInflater layoutInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
layoutInflater.inflate(R.layout.my_layout_name, this);

answered Oct 16, 2014 at 9:21

Denley Bihari

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6 Comments

Lauris01 Over a year ago

Please see my update, i don't see NullPointerException

Denley Bihari Over a year ago

Ah I see. It's not actually finding the class at all. I'm not quite sure how to fix your existing problem, but I guarantee you will see the NullPointerException once you have the ClassNotFoundException fixed.

Lauris01 Over a year ago

Instead of Imageview, what i should use to try this ?

Denley Bihari Over a year ago

Just use View. It's worth a shot since it seems to have worked for them. But I've definitely seen it work the way you currently have it too, I'm just not sure why yours is failing.

Lauris01 Over a year ago

can i ask for similar problem here or i should create new question ?

|

Allan · Accepted Answer · 2014-10-16 09:35:06Z

0

Why you called in your constructor this:

drawView = (DrawingView) findViewById(R.id.drawing);
LinearLayout paintLayout = (LinearLayout) findViewById(R.id.paint_colors);

You are already in your DrawingView, so you can't find DrawingView with drawing id. It's the same for paintLayout, your DrawingView haven't LinearLayout with id paint_colors. Your DrawingView is only a View not a ViewGroup

I think you have a NullPointerException at this line:

currPaint = (ImageButton) paintLayout.getChildAt(0);

Before this line test if your paintLayout is null please.

answered Oct 16, 2014 at 9:35

Allan

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3 Comments

Lauris01 Over a year ago

yes, i can see that paintlayout is nullbefore executing currPaint = (ImageButton) paintLayout.getChildAt(0); line

Allan Over a year ago

ok it's normal you can't do this. Your DrawingView can't see the paint_colors LinearLayout because the LinearLayout isn't include in your DrawingView. The LinearLayout and the DrawingView are at the same level in your view hierarchy.

Allan Over a year ago

@DenleyBihari oops yes sorry! :s

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