Unfortunatly, Sudoku has stopped

[shivam singhal]

I am new in android development.. and my app showing "Unfortunatly, Sudoku has stopped" please help..
LOGCAT

04-05 10:31:42.061: E/AndroidRuntime(848): FATAL EXCEPTION: main

04-05 10:31:42.061: E/AndroidRuntime(848): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sudoku/com.example.sudoku.Sudoku}: java.lang.NullPointerException

04-05 10:31:42.061: E/AndroidRuntime(848): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.app.ActivityThread.access$600(ActivityThread.java:141)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.os.Handler.dispatchMessage(Handler.java:99)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.os.Looper.loop(Looper.java:137)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.app.ActivityThread.main(ActivityThread.java:5039)

04-05 10:31:42.061: E/AndroidRuntime(848): at java.lang.reflect.Method.invokeNative(Native Method)

04-05 10:31:42.061: E/AndroidRuntime(848): at java.lang.reflect.Method.invoke(Method.java:511)

04-05 10:31:42.061: E/AndroidRuntime(848): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)

04-05 10:31:42.061: E/AndroidRuntime(848): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)

04-05 10:31:42.061: E/AndroidRuntime(848): at dalvik.system.NativeStart.main(Native Method)

04-05 10:31:42.061: E/AndroidRuntime(848): Caused by: java.lang.NullPointerException

04-05 10:31:42.061: E/AndroidRuntime(848): at com.example.sudoku.Sudoku.onCreate(Sudoku.java:24)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.app.Activity.performCreate(Activity.java:5104)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)

04-05 10:31:42.061: E/AndroidRuntime(848): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)

04-05 10:31:42.061: E/AndroidRuntime(848): ... 11 more

04-05 10:31:46.191: I/Process(848): Sending signal. PID: 848 SIG: 9

[Ulf Dittmer]

That's the important part: Caused by: java.lang.NullPointerException at com.example.sudoku.Sudoku.onCreate(Sudoku.java:24)

You need to find out which object is null in that line of code, and deal with that.

[Steve Luke]

shivam singhal wrote:04-05 10:31:42.061: E/AndroidRuntime(848): FATAL EXCEPTION: main
04-05 10:31:42.061: E/AndroidRuntime(848): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sudoku/com.example.sudoku.Sudoku}: java.lang.NullPointerException

You have a Null Pointer Exception

...
04-05 10:31:42.061: E/AndroidRuntime(848): Caused by: java.lang.NullPointerException
04-05 10:31:42.061: E/AndroidRuntime(848): at com.example.sudoku.Sudoku.onCreate(Sudoku.java:24)

On Sudoku line 24, in the onCreate() method. Some object you are trying to use there is null, and needs to be not null.

[shivam singhal]

Thanks Steve..

[shivam singhal]

protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.sudoku_main);
		    
		       View ContinueButton = findViewById(R.id.continue_label);
//next is line 24 			
                       ContinueButton.setOnClickListener(this);
			
			View PlayButton = findViewById(R.id.play_label);
			PlayButton.setOnClickListener(this);
			
			View AboutButton = findViewById(R.id.about_content);
			AboutButton.setOnClickListener(this);
			
			View ExitButton = findViewById(R.id.exit_label);
			ExitButton.setOnClickListener(this);
		
	}

what else i am missin in line 24?

[Steve Luke]

shivam singhal wrote:what else i am missin in line 24?

Apparently an object ;)

Check the layout and make sure that the view you are trying to use exists and has the id set to continue_label. You might have different layouts in different resource folders based on screen size, language, or rotation. So double check all locations.

[shivam singhal]

sorry unable to find my error..

here is my strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">Sudoku</string>
    <string name="sudoku">Android Sudoku</string>
    <string name="menu_settings">Settings</string>
    <string name="continue_label">Continue</string>
    <string name="play_label">Play</string>
    <string name="settings_label">Settings</string>
    <string name="exit_label">Exit</string>
    <string name="about">Sudoku is a logic-based number placement puzzle. Starting with a 
partially completed 9x9 grid, theobjective is to fill the grid so that eachrow, each column, and each of the 3x3 boxes(also called 
<i>blocks</i>) contains the digits1 to 9 exactly once.</string>
    <string name="music_title">Music</string>
    <string name="music_summary">Music Summary</string>
    <string name="hints_title">Hints</string>
    <string name="hints_summary">Hints Summary</string>

    <string name="Difficulty">DIFICULTY LEVEL</string>
    <string name="easy">Easy</string>
    <string name="medium">Medium</string>
    <string name="hard">Hard</string>

and my R.java file

/* AUTO-GENERATED FILE.  DO NOT MODIFY.
 *
 * This class was automatically generated by the
 * aapt tool from the resource data it found.  It
 * should not be modified by hand.
 */

package com.example.sudoku;

public final class R {
    public static final class array {
        public static final int difficulty=0x7f050000;
    }
    public static final class attr {
    }
    public static final class color {
        public static final int background=0x7f060000;
    }
    public static final class drawable {
        public static final int ic_launcher=0x7f020000;
    }
    public static final class id {
        public static final int about_content=0x7f0a0000;
        public static final int continue_label=0x7f0a0001;
        public static final int exit_label=0x7f0a0004;
        public static final int menu_settings=0x7f0a0005;
        public static final int play_label=0x7f0a0002;
        public static final int settings_label=0x7f0a0003;
    }
    public static final class layout {
        public static final int activity_sudoku=0x7f030000;
        public static final int anout=0x7f030001;
        public static final int sudoku_main=0x7f030002;
    }
    public static final class menu {
        public static final int activity_sudoku=0x7f090000;
    }
    public static final class string {
        public static final int Difficulty=0x7f07000c;
        public static final int about=0x7f070007;
        public static final int app_name=0x7f070000;
        public static final int continue_label=0x7f070003;
        public static final int easy=0x7f07000d;
        public static final int exit_label=0x7f070006;
        public static final int hard=0x7f07000f;
        public static final int hints_summary=0x7f07000b;
        public static final int hints_title=0x7f07000a;
        public static final int medium=0x7f07000e;
        public static final int menu_settings=0x7f070002;
        public static final int music_summary=0x7f070009;
        public static final int music_title=0x7f070008;
        public static final int play_label=0x7f070004;
        public static final int settings_label=0x7f070005;
        public static final int sudoku=0x7f070001;
    }
    public static final class style {
        /** 
        Base application theme, dependent on API level. This theme is replaced
        by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
    

            Theme customizations available in newer API levels can go in
            res/values-vXX/styles.xml, while customizations related to
            backward-compatibility can go here.
        

        Base application theme for API 11+. This theme completely replaces
        AppBaseTheme from res/values/styles.xml on API 11+ devices.
    
 API 11 theme customizations can go here. 

        Base application theme for API 14+. This theme completely replaces
        AppBaseTheme from BOTH res/values/styles.xml and
        res/values-v11/styles.xml on API 14+ devices.
    
 API 14 theme customizations can go here. 
         */
        public static final int AppBaseTheme=0x7f080000;
        /**  Application theme. 
 All customizations that are NOT specific to a particular API-level can go here. 
         */
        public static final int AppTheme=0x7f080001;
    }
    public static final class xml {
        public static final int settings=0x7f040000;
    }
}

[Steve Luke]

shivam singhal wrote:here is my strings.xml
...
and my R.java file

Thats all well and good, but, as I said, the place you should be looking is your layout.

[shivam singhal]

I am Working on eclipse(ADT)
And I think the naming mistake couldn't happen in eclipse as on every moment when i am writing the code IDE always looking up for the same name in the defined file..

Steve I am New to Android Development and there are lots of files linked with each other may be that's why I am unable to findout my error..

Here is the layout file, that I am using

        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:orientation="vertical"
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:gravity="center"
        android:padding="30dip" 
        tools:context=".Sudoku"
        android:background="@color/background" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="24.5dip"
        android:gravity="center"
        android:paddingTop="15dip"
        android:text="@string/sudoku" />
 
    <TableLayout 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center">
        
    <TableRow>
    <Button
        android:id="@+id/continue_label"
        android:text="@string/continue_label"/>

    <Button
        android:id="@+id/play_label"
        android:text="@string/play_label"/>
    </TableRow>
    <TableRow>
        <Button
        android:id="@+id/settings_label"
        android:text="@string/settings_label"/>    
    
    <Button
       android:id="@+id/exit_label"
        android:text="@string/exit_label"/>
    </TableRow>
    </TableLayout>
    </LinearLayout>

[shivam singhal]

Now., I Think have found my mistake..
Thanks steve..

[shivam singhal]

please tell me one thing ..
how do you know that its a layout problem??

[Steve Luke]

shivam singhal wrote:please tell me one thing ..
how do you know that its a layout problem??

I didn't know, but I had a strong inkling it was layout related.

The line you pointed to had two references in it, this and ContinueButton. The value pointed to by this can't be null. so the other reference had to be null. The ContinueButton was retrieved by findViewById(), which, as you can see in the API returns null when the view can't be found. The id you pass in must exist, or at least existed in the past, because it was present in R.id. So if the View exists and it isn't found then the view must not be present in the current layout. That means your layout might not be what you think it is. There is plenty of room for this type of mistake so it seemed a likely cause of the problem (a problem I have stepped into a fair amount of times).

[shivam singhal]

Thanks steve..

Done ..