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android application is exited when override function from custom view

I have a custom view and want to display it, however if I call the method from the custom view (setOnClickListener,...) the application will automatically exit, I don't know why and hope everyone answers.
public class MotionEventActivity extends AppCompatActivity{
#SuppressLint("ClickableViewAccessibility")
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//MyView myView = new MyView(this);
setContentView(R.layout.motion_view);
MyView myView = findViewById(R.id.main);
myView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
}
});
}
}
And here is the code of the custom view:
public class MyView extends View {
public Paint paint = null;
public int radius = 82;
public List<CoordinateButton> arrButton = new ArrayList<CoordinateButton>();
MyView(Context context){
this(context, null);
}
public MyView(Context context, AttributeSet attributeSet) {
super(context);
arrButton.add(new CoordinateButton("S",(float)46.0 , (float) 37.0, 1, "#F08080", "#DC143C", "#F08080"));
arrButton.add(new CoordinateButton("H",(float)1866.0 , (float) 699.0, 4, "#F0E68C", "#FFFF00", "#F0E68C"));
paint = new Paint();
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for(CoordinateButton button : arrButton){
paint.setColor(Color.parseColor(button.getColorButton()));
canvas.drawCircle(button.getXButton() + radius, button.getYButton() + radius, radius, paint);
paint.setColor(Color.BLACK);
paint.setTextSize(45);
paint.setTextAlign(Paint.Align.CENTER);
canvas.drawText(button.getTextButton(),button.getXButton() + radius, button.getYButton() + radius +15, paint);
}
}
}
And here is the code of the xml file:
<?xml version="1.0" encoding="utf-8"?>
<com.example.motionevent.MyView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MotionEventActivity">
</com.example.motionevent.MyView>

onTouch and OnDraw in SurfaceView

I am trying to draw based on my trace over the screen. In this process my onTouch and OnDraw is not being executed. Could you please assist me to correct this code ?
Xml
<LinearLayout
xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="100"
android:orientation="vertical"
android:background="#ffff0000" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="60"
android:gravity="center" >
<com.example.test2.PathDraw
android:id="#+id/surfaceView"
android:layout_width="match_parent"
android:layout_height="140dp" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="40"
android:gravity="center" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/lion" />
</LinearLayout>
MainActivity
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
PathDraw sineWaveSurfaceView = (PathDraw) findViewById(R.id.surfaceView);
}
}
PathDraw
public class PathDraw extends SurfaceView implements SurfaceHolder.Callback
{
private Context context;
// List<Point> points;
ArrayList<Point> points = new ArrayList<Point>();
public PathDraw(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
public PathDraw(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
this.context = context;
getHolder().addCallback(this);
}
public PathDraw(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
}
protected void OnDraw(Canvas canvas, int value) {
Paint paint = new Paint();
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(2);
paint.setColor(Color.WHITE);
Path path = new Path();
boolean first = true;
for(Point point : points){
if(first){
first = false;
path.moveTo(point.x, point.y);
}
else{
path.lineTo(point.x, point.y);
}
}
canvas.drawPath(path, paint);
}
public boolean onTouch(View view, MotionEvent event) {
// if(event.getAction() != MotionEvent.ACTION_DOWN)
// return super.onTouchEvent(event);
Point point = new Point();
point.x = event.getX();
point.y = event.getY();
points.add(point);
invalidate();
Log.d("PathDraw", "point: " + point);
return true;
}
#Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub
}
#Override
public void surfaceCreated(SurfaceHolder arg0) {
// TODO Auto-generated method stub
}
#Override
public void surfaceDestroyed(SurfaceHolder arg0) {
// TODO Auto-generated method stub
}
}

OnTouch is not called
I also had the exact same problem earlier today.
Class PathDraw should implement OnTouchListener, then set the listener to itself, do something like this:
public class PathDraw extends SurfaceView implements OnTouchListener, SurfaceHolder.Callback{
...
public PathDraw(Context context){
super(context);
setOnTouchListener(PathDraw.this);
}
OnDraw is not called
This post might help:
Android Custom Layout - onDraw() never gets called

setting onClickListener on views drawn on a canvas

So basically I have some image views drawn over my canvas, but when I try to set up onclick listeners and try to handle events, it doesn't work.
public class DrawView extends View implements OnClickListener{
Paint paint = new Paint();
RectF rf = new RectF(30, 30, 80, 80);
BallView ball = new BallView(getContext());
Bitmap bmp = BitmapFactory.decodeResource(getContext().getResources(), R.drawable.ic_launcher);
public DrawView(Context context) {
super(context);
}
#Override
public void onDraw(Canvas canvas) {
ball.setOnClickListener(this);
ball.draw(canvas);
canvas.drawBitmap(bmp, 110, 10, paint);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Toast.makeText(getContext(), "Mock", Toast.LENGTH_SHORT).show();
}
}
BallView.java
public class BallView extends ImageView {
Paint b = new Paint();
public BallView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
public void onDraw(Canvas c){
b.setColor(Color.BLUE);
c.drawCircle(50, 50, 40, b);
}
}

Basically the answer is: Your view is not receiving touch events, because it's not in views hierarchy, so click callback is also not called. Actually, view should be in View hierarchy (in other words, added to some upper level view and finally, to the window) in order to participate is user interactions.
So, if You want to implement somthing covering Your view, then it should be ViewGroup or shouldn't be related to view at all and be some abstract container.
E.g. using the way below click works without any issues (but You will need second view or modify BallView to draw bmp):
DrawView:
public class DrawView extends FrameLayout implements View.OnClickListener {
BallView ball = new BallView(getContext());
public DrawView(Context context) {
this(context, null, 0);
}
public DrawView(final Context context, final AttributeSet attrs) {
this(context, attrs, 0);
}
public DrawView(final Context context, final AttributeSet attrs, final int defStyle) {
super(context, attrs, defStyle);
addView(ball);
ball.setOnClickListener(this);
}
#Override
public void onClick(View v) {
Toast.makeText(getContext(), "Mock", Toast.LENGTH_SHORT).show();
}
}
BallView class stays the same.
Layout:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.ruinalst.performance.tests.views.DrawView
android:id="#+id/oscillator"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true" />
</RelativeLayout>

How to display the Canvas part of a view in android?

I am working on a code where we use canvas to detect the touch on the screen.As of now the canvas is been directly drawn.How to add it as part of a view which comprises of other elements in xml.Here is the code
public class Tutorial2D extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(new Panel(this));
}
}
Here is the other part of it
public class Panel extends SurfaceView implements SurfaceHolder.Callback {
private ViewThread mThread;
private ArrayList<Element> mElements = new ArrayList<Element>();
public Panel(Context context) {
super(context);
getHolder().addCallback(this);
mThread = new ViewThread(this);
}
public void doDraw(Canvas canvas) {
canvas.drawColor(Color.TRANSPARENT);
synchronized (mElements) {
for (Element element : mElements) {
element.doDraw(canvas);
}
}
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// TODO Auto-generated method stub
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
if (!mThread.isAlive()) {
mThread = new ViewThread(this);
mThread.setRunning(true);
mThread.start();
}
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
if (mThread.isAlive()) {
mThread.setRunning(false);
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
synchronized (mElements) {
mElements.add(new Element(getResources(), (int) event.getX(), (int) event.getY()));
}
return super.onTouchEvent(event);
}
}
How to add this canvas to the main xml and been displayed over an image,any snippet on this or how should I change working on this code,anything will be greatful.Thanks

Try this constructor for the Panel class:
public Panel(Context context, AttributeSet attrs) {
super(context, attrs);
getHolder().addCallback(this);
mThread = new ViewThread(this);
}

You can use the custom view in xml layout with its package name. For example, in main.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Hello" />
<your.package.name.Panel
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
Then, in onCreate of your activity:
setContentView(R.layout.main);

It is possible to set the text of a "TextView" from within a class 'extends View'

I've insert a custom View called "disegno" inside a Layout xml:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="?windowsBackground">
<it.package.myapp.Disegno
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/finestraDisegno"
android:isScrollContainer="true" />
<FrameLayout
android:layout_height="0dp"
android:layout_width="0dp"
...
<EditText
...
android:id="#+id/et_MOD_x">
</EditText>
Then I've implemented the extends View class for populate the custom layout:
package it.package.myapp;
import android.content.Context;
...
public class Disegno extends View {
public Disegno(Context context) {
this(context, null, 0); }
public Disegno(Context context, AttributeSet attrs) {
this(context, attrs, 0);
setContentView(R.layout.main); }
public Disegno(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
init(attrs); }
...
#Override
protected void onDraw(Canvas canvas) {
paint.setStyle(Paint.Style.FILL);
paint.setAntiAlias(true);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
// chiamo routine assi cartesiani
AssiCartesiani(canvas);
// chiamo routine polilinea
Polilinea(canvas); }
...
Now I would to set the text of the textView "et_MOD_x" by "findViewById(R.Id.et_MOD_x)" changing the code like this:
#Override
protected void onDraw(Canvas canvas) {
paint.setStyle(Paint.Style.FILL);
paint.setAntiAlias(true);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
// chiamo routine assi cartesiani
AssiCartesiani(canvas);
// chiamo routine polilinea
Polilinea(canvas);
EditText et_MOD_x = (EditText) findViewById(R.Id.et_MOD_x)
et_MOD_x.setText("abcd");
}
but without "setContentView(...)" is not possible!
Summing: I would to set the text of a "EditText" from within an "extends View" class. I'd to pointing to an external layout... mmmhh!
There is any way to do this?!

have a reference in your custom view
public class Disegno extends View {
private TextView textView;
public void setTextView(TextView tv){
textview = tv;
}
#Override
protected void onDraw(Canvas canvas) {
textview.setText("Your text here!")
}
}
in your Activity.onCreate()
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setContentView(R.layout.my_layout);
EditText et_MOD_x = (EditText) findViewById(R.Id.et_MOD_x);
Disegno finestraDisegno = (Disegno)findViewById(R.Id.finestraDisegno);
finestraDisegno.setTextView(et_MOD_x) ;
}

May be this is not the right way but you can :
Get your editText in your activity and declare it as static.
public static EditText et_MOD_x;
et_MOD_x = (EditText) findViewById(R.Id.et_MOD_x)
and In your View class set the text by :
YourActivity.et_MOD_x.setText("abcd");
Hope it helps..