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POError when creating a custom view
 

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  1. POError when creating a custom view
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    <p>I'm very new to android. I've been reading a whole lot of tutorials. But I want to get a simple piece of code to work. I want to do a card game. So I thought I'd start with creating a class that draws a rounded rectangle of a specific dimiension (I don't want to sell or share the game so portability is not an issue). </p> <p>This is the class I wrote:</p> <pre><code>public class Card extends View{ RectF borders; Paint paint; float rad; public Card(Context context) { super(context); // TODO Auto-generated constructor stub borders.set((float)0.0, (float)0.0, (float)2.5, (float)3.5); rad = 1; paint.setARGB(0, 117, 217, 222); } protected void onDraw(Canvas canvas){ canvas.drawRoundRect(borders, rad, rad, paint); } } </code></pre> <p>I created a Linear layout in xml and then this is code for the main activity:</p> <pre><code>public class MainActivity extends Activity { LinearLayout HandLayout; Card card; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); HandLayout = (LinearLayout)findViewById(R.id.hand_gallery); HandLayout.addView(card); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } } </code></pre> <p>When I execute that I get an NullPointer Exception. My guess is because I should add a line like card = new Card(context) but I don't know where to get the context...</p> <p>Thanks for any help!!!</p> <p>EDIT: </p> <p>This is the error code</p> <pre><code>12-14 14:23:36.900: E/AndroidRuntime(22580): FATAL EXCEPTION: main 12-14 14:23:36.900: E/AndroidRuntime(22580): java.lang.RuntimeException: Unable to start activity ComponentInfo{legen.dary/legen.dary.MainActivity}: java.lang.NullPointerException 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.app.ActivityThread.access$600(ActivityThread.java:130) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.os.Handler.dispatchMessage(Handler.java:99) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.os.Looper.loop(Looper.java:137) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.app.ActivityThread.main(ActivityThread.java:4745) 12-14 14:23:36.900: E/AndroidRuntime(22580): at java.lang.reflect.Method.invokeNative(Native Method) 12-14 14:23:36.900: E/AndroidRuntime(22580): at java.lang.reflect.Method.invoke(Method.java:511) 12-14 14:23:36.900: E/AndroidRuntime(22580): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 12-14 14:23:36.900: E/AndroidRuntime(22580): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 12-14 14:23:36.900: E/AndroidRuntime(22580): at dalvik.system.NativeStart.main(Native Method) 12-14 14:23:36.900: E/AndroidRuntime(22580): Caused by: java.lang.NullPointerException 12-14 14:23:36.900: E/AndroidRuntime(22580): at legen.dary.Card.&lt;init&gt;(Card.java:18) 12-14 14:23:36.900: E/AndroidRuntime(22580): at legen.dary.MainActivity.onCreate(MainActivity.java:28) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.app.Activity.performCreate(Activity.java:5008) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 12-14 14:23:36.900: E/AndroidRuntime(22580): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023) 12-14 14:23:36.900: E/AndroidRuntime(22580): ... 11 more </code></pre> <p>I have tried the following changes to code:</p> <pre><code>public class MainActivity extends Activity { LinearLayout HandLayout; Card card; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); HandLayout = (LinearLayout)findViewById(R.id.hand_gallery); card = new Card(this); HandLayout.addView(card); } } </code></pre>
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