Newbie - Force close on simple method

xml and logcat now added, now custom view code, unfortunately i am away from devel computer so i cant check your suggestio开发者_如何转开发ns, @jems, i may have the wrong constructor for my custom view? @Falmarri, i think the build target is 2.2

Hopefully a simple thing I don't know about:

I have a main game activity, and this calls a class which i have extended from the view class. Here it is, in working form:

public class guappsXOMainGame extends Activity {

private static final int cellsX=10;
private static final int cellsY=10;

private guappsXOBoardView mBoardView;



@Override
public void onCreate(Bundle bund) {
    super.onCreate(bund);


    setContentView(R.layout.gamescreen);//loads xml layout called gamescreen
    mBoardView = (guappsXOBoardView) findViewById(R.id.boardview);

}

It all was going well, showing my game screen well, until I tried the following, which gives a force close:

public void onCreate(Bundle bund) {
    super.onCreate(bund);

    setContentView(R.layout.gamescreen);//loads xml layout called gamescreen
    mBoardView = (guappsXOBoardView) findViewById(R.id.boardview);
    mBoardView.hello();//problem line



}

What I want is to run a method that will get some info from the guappsxoboardview class, and this was the test case. The method looks like this:

    public void hello(){

    int x = 1;

}

LogCat says:

01-29 20:50:46.415: INFO/ActivityManager(60): Starting activity: Intent { cmp=com.guapps/.guappsXOMainGame }
01-29 20:50:46.535: DEBUG/AndroidRuntime(564): Shutting down VM
01-29 20:50:46.535: WARN/dalvikvm(564): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
01-29 20:50:46.566: ERROR/AndroidRuntime(564): FATAL EXCEPTION: main
01-29 20:50:46.566: ERROR/AndroidRuntime(564): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.guapps/com.guapps.guappsXOMainGame}: java.lang.NullPointerException
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.os.Looper.loop(Looper.java:123)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.app.ActivityThread.main(ActivityThread.java:4627)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at java.lang.reflect.Method.invokeNative(Native Method)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at java.lang.reflect.Method.invoke(Method.java:521)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at dalvik.system.NativeStart.main(Native Method)
01-29 20:50:46.566: ERROR/AndroidRuntime(564): Caused by: java.lang.NullPointerException
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at com.guapps.guappsXOMainGame.onCreate(guappsXOMainGame.java:38)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
01-29 20:50:46.566: ERROR/AndroidRuntime(564):     ... 11 more
01-29 20:50:46.596: WARN/ActivityManager(60):   Force finishing activity com.guapps/.guappsXOMainGame
01-29 20:50:46.596: WARN/ActivityManager(60):   Force finishing activity com.guapps/.guappsXOStart
01-29 20:50:46.745: DEBUG/dalvikvm(60): GC_FOR_MALLOC freed 7966 objects / 468848 bytes in 99ms
01-29 20:50:47.108: WARN/ActivityManager(60): Activity pause timeout for HistoryRecord{44009a08 com.guapps/.guappsXOMainGame}
01-29 20:50:48.375: INFO/Process(564): Sending signal. PID: 564 SIG: 9
01-29 20:50:48.385: INFO/ActivityManager(60): Process com.guapps (pid 564) has died.
01-29 20:50:48.385: INFO/WindowManager(60): WIN DEATH: Window{440530d0 com.guapps/com.guapps.guappsXOStart paused=true}
01-29 20:50:48.445: WARN/InputManagerService(60): Got RemoteException sending setActive(false) notification to pid 564 uid 10032
01-29 20:50:57.482: WARN/ActivityManager(60): Activity destroy timeout for HistoryRecord{43fc4248 com.guapps/.guappsXOStart}
01-29 20:50:57.488: WARN/ActivityManager(60): Activity destroy timeout for HistoryRecord{44009a08 com.guapps/.guappsXOMainGame}

Here is the XML for this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center_horizontal"
>

<com.guapps.guappsXOBoardView
    android:id="@+id/boardview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"


    />

</LinearLayout>

Hopefully I have done something obvious wrong, thanks.

Now most of the custom view code also:

package com.guapps;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;



public class guappsXOBoardView extends View {

    int screenHeight;
    int screenWidth;
    Context mContext;
    private float leftG;
    private float topG;
    private float rightG;
    private float botG;




    Bitmap boardGrid;




    public guappsXOBoardView(Context context, AttributeSet attrs) {
            super(context);
            requestFocus();


    }


    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){

        screenWidth = View.MeasureSpec.getSize(widthMeasureSpec);
        screenHeight = View.MeasureSpec.getSize(heightMeasureSpec);

        setMeasuredDimension(screenWidth, screenHeight);


    }

    @Override
    protected void onDraw(Canvas canvas){



        canvas.drawColor(Color.WHITE);


         }
.....

Seems stupid but so many people forget... Did you add the activity to the Manifest?

Maybe try to remove the requestFocus() from the constructor. Why do you need it anyway?

thanks for you help, I found my bug.

The constructor of my custom view had super(context); instead of super(context, attrs), which was causing findviewbyid to return null.