App mit zwei Klassen in Android Studio

package grafik1.carpelibrum.de.grafik1;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.RelativeLayout;


public class GrafikActivity extends ActionBarActivity {

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

        // selbst eingefügt
        RelativeLayout layout = (RelativeLayout) findViewById(R.id.layout1);
        layout.addView(layout);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_grafik, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

<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="250dp"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".GrafikActivity">

    <de.carpelibrum.grafik.ZeichnenView
        android:id="@+id/layout1"
        android:layout_width="match_parent"
        android:layout_height="250dp"
        android:background="#ffff00"/>
</RelativeLayout>

package de.carpelibrum.grafik;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

/**
 * Created by lard on 29.01.15.
 */
public class ZeichnenView extends View {
    public ZeichnenView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    // nicht generierter Teil:
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // 1. Paint-Objekt für Blau und 5Px Breite
        Paint pinsel = new Paint();
        pinsel.setColor(Color.rgb(64, 64, 255));
        pinsel.setStrokeWidth(5);
        // Diagonale durch Leinwand zeichnen
        canvas.drawLine(0, 0, getWidth(), getHeight(), pinsel);
    }
}

---- beginning of crash
01-29 16:58:15.182    1934-1934/grafik1.carpelibrum.de.grafik1 E/AndroidRuntime FATAL EXCEPTION: main
    Process: grafik1.carpelibrum.de.grafik1, PID: 1934
     java.lang.RuntimeException: Unable to start activity  ComponentInfo{grafik1.carpelibrum.de.grafik1/grafik1.carpelibrum.de.grafik1.GrafikActivity}:  android.view.InflateException: Binary XML file line #11: Error  inflating class de.carpelibrum.grafik.ZeichnenView
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
      Caused by: android.view.InflateException: Binary XML file line #11:  Error inflating class de.carpelibrum.grafik.ZeichnenView
            at android.view.LayoutInflater.createView(LayoutInflater.java:616)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
            at android.support.v7.app.ActionBarActivityDelegateBase.setContentView(ActionBarActivityDelegateBase.java:228)
            at android.support.v7.app.ActionBarActivity.setContentView(ActionBarActivity.java:102)
            at grafik1.carpelibrum.de.grafik1.GrafikActivity.onCreate(GrafikActivity.java:15)
            at android.app.Activity.performCreate(Activity.java:5933)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.NoSuchMethodException: <init> [class and