I keep facing this type of error about java.lng.NullPointerExeption .Anyone know how to solve it ?
main.java
package com.example.shoppingassistantnew;
import greendroid.app.GDActivity;
import greendroid.widget.ActionBarItem;
import greendroid.widget.ActionBarItem.Type;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.MenuItem;
import android.support.v4.app.NavUtils;
public class main extends GDActivity {
private static final int EXPAND = 0;
private static final int ADD = 1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setActionBarContentView(R.layout.shoppinglist);
initActionBar();
}
private void initActionBar(){
addActionBarItem(Type.List,EXPAND);
addActionBarItem(Type.Add,ADD);
}
@Override
public boolean onHandleActionBarItemClick(ActionBarItem item, int position) {
// TODO Auto-generated method stub
switch(item.getItemId()){
case ADD:
Intent intent=new Intent(main.this,AddShoppingList.class);
startActivity(intent);
}
return super.onHandleActionBarItemClick(item, position);
}
static final class ProductData{
String barcode;
String format;
}
}
AddShoppingList.java
package com.example.shoppingassistantnew;
import com.cyrilmottier.android.greendroid.R;
import com.example.shoppingassistantnew.main.ProductData;
import android.app.ActionBar.LayoutParams;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import greendroid.app.GDActivity;
public class AddShoppingList extends Activity implements OnClickListener {
private static final ProductData mProductData = new ProductData();
private Button mSaveBttn;
EditText mBarcodeEdit;
EditText mFormatEdit;
ProductDatabase mProductDb;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.addshoppinglist);
mBarcodeEdit = (EditText) findViewById(R.id.shoppingListNameEdit);
mFormatEdit = (EditText) findViewById(R.id.shoppingDateEdit);
mSaveBttn.setOnClickListener(this);
}
private void showInfoDialog(Context context, String title,
String information) {
new AlertDialog.Builder(context).setMessage(information)
.setTitle(title)
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
}).show();
}
public void onClick(View v) {
// TODO Auto-generated method stub
}
}
ProductDatabase.java
package com.example.shoppingassistantnew;
import com.example.shoppingassistantnew.main.ProductData;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class ProductDatabase {
private static final String PRODUCT_TABLE="products";
private static final String DATABASE_NAME="spot_pay.db";
private static final int DATABASE_VERSION=1;
private SQLiteDatabase db;
private static class ProductDatabaseHelper extends SQLiteOpenHelper {
private static final String TAG = null;
public ProductDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
StringBuilder sql=new StringBuilder();
sql.append("create table ").append(PRODUCT_TABLE)
.append("( ")
.append(" _id integer primary key,")
.append(" barcode text,")
.append(" format text,")
.append(") ");
db.execSQL(sql.toString());
Log.d(TAG, PRODUCT_TABLE + "table created");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
db.execSQL("drop table if exists " + PRODUCT_TABLE);
onCreate(db);
}
}
public ProductDatabase(Context context){
ProductDatabaseHelper helper = new ProductDatabaseHelper(context);
db = helper.getWritableDatabase();
}
public boolean insert(ProductData product){
ContentValues vals = new ContentValues();
vals.put("barcode", product.barcode);
vals.put("format", product.format);
return db.insert(PRODUCT_TABLE, null, vals) != -1;
}
}
AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.shoppingassistantnew"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="7"
android:targetSdkVersion="15" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/Theme.GDActionBarExample"
android:name=".GDIntroApp">
<activity
android:name=".main"
android:label="@string/title_activity_main" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".AddShoppingList" android:theme="@style/myDialog"></activity>
</application>
</manifest>
LOGCAT
10-27 10:18:15.545: D/AndroidRuntime(1633): Shutting down VM
10-27 10:18:15.545: W/dalvikvm(1633): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
10-27 10:18:15.555: E/AndroidRuntime(1633): FATAL EXCEPTION: main
10-27 10:18:15.555: E/AndroidRuntime(1633): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.shoppingassistantnew/com.example.shoppingassistantnew.AddShoppingList}: java.lang.NullPointerException
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.os.Handler.dispatchMessage(Handler.java:99)
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.os.Looper.loop(Looper.java:123)
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.app.ActivityThread.main(ActivityThread.java:4627)
10-27 10:18:15.555: E/AndroidRuntime(1633): at java.lang.reflect.Method.invokeNative(Native Method)
10-27 10:18:15.555: E/AndroidRuntime(1633): at java.lang.reflect.Method.invoke(Method.java:521)
10-27 10:18:15.555: E/AndroidRuntime(1633): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
10-27 10:18:15.555: E/AndroidRuntime(1633): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
10-27 10:18:15.555: E/AndroidRuntime(1633): at dalvik.system.NativeStart.main(Native Method)
10-27 10:18:15.555: E/AndroidRuntime(1633): Caused by: java.lang.NullPointerException
10-27 10:18:15.555: E/AndroidRuntime(1633): at com.example.shoppingassistantnew.AddShoppingList.onCreate(AddShoppingList.java:39)
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-27 10:18:15.555: E/AndroidRuntime(1633): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
10-27 10:18:15.555: E/AndroidRuntime(1633): ... 11 more
10-27 10:18:17.825: I/Process(1633): Sending signal. PID: 1633 SIG: 9
in
AddShoppingList.java ,mSaveBttn is nullgive refrence first from xml , then use it