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I have created a custom View which draws a line:

public class DrawView extends View { Paint paint = new Paint(); public DrawView(Context context) { super(context); paint.setColor(Color.BLACK); } @Override public void onDraw(Canvas canvas) { canvas.drawLine(0, 0, 100, 100, paint); } }

I have a MainActivity class and activity_main layout where my layout contains an image and several buttons. I want to put the custom view that I created to my XML file(activity_main) where a line would be drawn on top of the image.

I tried adding it:

<RelativeLayout 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" tools:context=".MainActivity"> //imageview and buttons here <com.myapp.alphasickbro.myapplication2.DrawView android:id="@+id/paintView" android:layout_width="100dp" android:layout_height="100dp" /> </RelativeLayout>

Here is my MainActivity:

public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } }

But when I run it, the app unfortunately stops. Did I miss something? What lines of code should I add?

Any answer would be appreciated

EDIT:

04-18 15:24:47.517 26732-26732/com.myapp.alphasickbro.myapplication2 E/AndroidRuntime﹕ FATAL EXCEPTION: main Process: com.myapp.alphasickbro.myapplication2, PID: 26732 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.alphasickbro.myapplication2/com.myapp.alphasickbro.myapplication2.MainActivity}: android.view.InflateException: Binary XML file line #6: Error inflating class com.myapp.alphasickbro.myapplication2.DrawView at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2318) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2396) at android.app.ActivityThread.access$800(ActivityThread.java:139) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:149) at android.app.ActivityThread.main(ActivityThread.java:5268) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:515) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609) at dalvik.system.NativeStart.main(Native Method) Caused by: android.view.InflateException: Binary XML file line #6: Error inflating class com.myapp.alphasickbro.myapplication2.DrawView at android.view.LayoutInflater.createView(LayoutInflater.java:620) at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:696) at android.view.LayoutInflater.rInflate(LayoutInflater.java:755) at android.view.LayoutInflater.inflate(LayoutInflater.java:492) at android.view.LayoutInflater.inflate(LayoutInflater.java:397) at android.view.LayoutInflater.inflate(LayoutInflater.java:353) at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290) at android.app.Activity.setContentView(Activity.java:2002) at com.myapp.alphasickbro.myapplication2.MainActivity.onCreate(MainActivity.java:15) at android.app.Activity.performCreate(Activity.java:5411) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2396)             at android.app.ActivityThread.access$800(ActivityThread.java:139)             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293)             at android.os.Handler.dispatchMessage(Handler.java:102)             at android.os.Looper.loop(Looper.java:149)             at android.app.ActivityThread.main(ActivityThread.java:5268)             at java.lang.reflect.Method.invokeNative(Native Method)             at java.lang.reflect.Method.invoke(Method.java:515)             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)             at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.reflect.InvocationTargetException at java.lang.reflect.Constructor.constructNative(Native Method) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at android.view.LayoutInflater.createView(LayoutInflater.java:594)             at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:696)             at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)             at android.view.LayoutInflater.inflate(LayoutInflater.java:492)             at android.view.LayoutInflater.inflate(LayoutInflater.java:397)             at android.view.LayoutInflater.inflate(LayoutInflater.java:353)             at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)             at android.app.Activity.setContentView(Activity.java:2002)             at com.myapp.alphasickbro.myapplication2.MainActivity.onCreate(MainActivity.java:15)             at android.app.Activity.performCreate(Activity.java:5411)             at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2396)             at android.app.ActivityThread.access$800(ActivityThread.java:139)             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293)             at android.os.Handler.dispatchMessage(Handler.java:102)             at android.os.Looper.loop(Looper.java:149)             at android.app.ActivityThread.main(ActivityThread.java:5268)             at java.lang.reflect.Method.invokeNative(Native Method)             at java.lang.reflect.Method.invoke(Method.java:515)             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)             at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.NullPointerException at com.myapp.alphasickbro.myapplication2.DrawView.<init>(DrawView.java:27)             at java.lang.reflect.Constructor.constructNative(Native Method)             at java.lang.reflect.Constructor.newInstance(Constructor.java:423)             at android.view.LayoutInflater.createView(LayoutInflater.java:594)             at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:696)             at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)             at android.view.LayoutInflater.inflate(LayoutInflater.java:492)             at android.view.LayoutInflater.inflate(LayoutInflater.java:397)             at android.view.LayoutInflater.inflate(LayoutInflater.java:353)             at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)             at android.app.Activity.setContentView(Activity.java:2002)             at com.myapp.alphasickbro.myapplication2.MainActivity.onCreate(MainActivity.java:15)             at android.app.Activity.performCreate(Activity.java:5411)             at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2270)             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2396)             at android.app.ActivityThread.access$800(ActivityThread.java:139)             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1293)             at android.os.Handler.dispatchMessage(Handler.java:102)             at android.os.Looper.loop(Looper.java:149)             at android.app.ActivityThread.main(ActivityThread.java:5268)             at java.lang.reflect.Method.invokeNative(Native Method)             at java.lang.reflect.Method.invoke(Method.java:515)             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)             at dalvik.system.NativeStart.main(Native Method)
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  • 1
    Please show log-cat result Commented Apr 18, 2015 at 6:26
  • You have created a paintView in XML, but you have not set the canvas to it. Commented Apr 18, 2015 at 6:40
  • @Iqbal How would I do that? Can you post it as an answer. Just a newbie here Commented Apr 18, 2015 at 6:44
  • @ρяσѕρєяK logcat result is displayed Commented Apr 18, 2015 at 6:46

1 Answer 1

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I think you need to add the missing constructors. Clean your project.

public class DrawView extends View { Paint paint; public DrawView(Context context) { super(context); init(); } public DrawView(Context context, AttributeSet attrs) { super(context, attrs); init(); } public DrawView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(); } private void init() { paint = new Paint(); paint.setColor(Color.BLACK); } }
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3 Comments

Missing constructors? I already created a constructor for DrawView, what else should I add.
When you use your view from xml, the constructor with attributeset is used, since you had none.. The problem. See edit.
I tried it but it still stopped when I run it. No errors but when ran, a lot of errors are shown in logcat. I updated my post, pls see logcat if necessary.

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