我一直在处理一个问题，由于我遇到错误，导致无法将编辑文本和整数中的数据添加到SQL数据库中，导致无法添加数据并使崩溃应用。
我很感谢大家的投入或任何解决方案，因为我不确定我在这里做错了什么，并且我尝试了许多方法来解决它。
记录错误消息：
> java.lang.NullPointerException: Attempt to invoke virtual method 'boolean
com.infined.needomvp.GoalDatabaseHelper.addData(java.lang.String, int)' on a null object reference
at com.infined.needomvp.GoalActivity.AddData(GoalActivity.java:99)
at com.infined.needomvp.GoalActivity.onOptionsItemSelected(GoalActivity.java:74)
at android.app.Activity.onMenuItemSelected(Activity.java:3450)
at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:407)
at android.support.v7.app.AppCompatActivity.onMenuItemSelected(AppCompatActivity.java:195)
at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:108)
at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:108)
at android.support.v7.app.ToolbarActionBar$2.onMenuItemClick(ToolbarActionBar.java:63)
at android.support.v7.widget.Toolbar$1.onMenuItemClick(Toolbar.java:203)
at android.support.v7.widget.ActionMenuView$MenuBuilderCallback.onMenuItemSelected(ActionMenuView.java:780)
at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:822)
at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:171)
at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:973)
at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:963)
at android.support.v7.widget.ActionMenuView.invokeItem(ActionMenuView.java:624)
at android.support.v7.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:150)
GoalDatabaseHelper：
public class GoalDatabaseHelper extends SQLiteOpenHelper {
public static final String TAG = "GoalDatabaseHelper";
public static final String TABLE_NAME_G = "goal_table";
public static final String COL1 = "_id";
public static final String COL2 = "name";
public static final String COL3 = "priority";
public GoalDatabaseHelper(Context context) {
super(context, TABLE_NAME_G, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
String createTable = "CREATE TABLE " + TABLE_NAME_G + " (_id INTEGER PRIMARY KEY AUTOINCREMENT, '" +
COL2 + "' TEXT ,'" + COL3 + "' INTEGER)";
db.execSQL(createTable);
}
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME_G);
onCreate(db);
}
public boolean addData(String name, int pri) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL2, name);
contentValues.put(COL3, pri);
Log.d(TAG, "addData: Adding " + name + " to " + TABLE_NAME_G);
long result = db.insert(TABLE_NAME_G, null, contentValues);
//if data as inserted incorrectly it will return -1
if (result == -1) {
return false;
} else {
return true;
}
}
public Cursor getItemID(String name){
SQLiteDatabase db = this.getWritableDatabase();
String query = "SELECT " + COL1 + " FROM " + TABLE_NAME_G +
" WHERE " + COL2 + " = '" + name + "'";
Cursor data = db.rawQuery(query, null);
return data;
}
public void deleteName(int id, String name){
SQLiteDatabase db = this.getWritableDatabase();
String query = "DELETE FROM " + TABLE_NAME_G + " WHERE "
+ COL1 + " = '" + id + "'" +
" AND " + COL2 + " = '" + name + "'";
Log.d(TAG, "deleteName: query: " + query);
Log.d(TAG, "deleteName: Deleting " + name + " from database.");
db.execSQL(query);
}
}
GoalActivity：
public class GoalActivity extends AppCompatActivity {
public static final String TAG = "GoalActivity";
private TextView title;
private EditText goalInput;
GoalDatabaseHelper mDatabaseHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_goal);
Toolbar toolbar = (Toolbar) findViewById(R.id.goalBar);
title = (TextView) findViewById(R.id.titleG);
goalInput = (EditText) findViewById(R.id.goalEnter);
Button DISPLAY = (Button)findViewById(R.id.DISPLAY);
setSupportActionBar(toolbar);
getSupportActionBar().setTitle("");
final Typeface face = Typeface.createFromAsset(getAssets(),
"fonts/SourceSansPro-SemiBold.ttf");
final Typeface regface = Typeface.createFromAsset(getAssets(),
"fonts/SourceSansPro-Regular.ttf");
final Typeface smallface = Typeface.createFromAsset(getAssets(),
"fonts/SourceSansPro-Light.ttf");
goalInput.setText("");
title.setTypeface(regface);
DISPLAY.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Log.d(TAG,"STAGE 0/1 addData: Adding ");
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.goal_bar, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == R.id.action_done_goal) {
String Name = goalInput.getText().toString();
int Pri = 100;
if (goalInput.length() != 0) {
AddData(Name, Pri);
toastMessage("Task Name is" + Name);
Intent i = new Intent(GoalActivity.this, GoalDisplayActivity.class);
Log.d(TAG,"STAGE 2 addData: Adding " + Name);
startActivity(i);
overridePendingTransition(R.anim.fade_in_q, R.anim.fade_out_q);
finish();
} else {
toastMessage("You must put something in the text field!");
}
}
if (id == R.id.action_back_goal) {
Toast.makeText(GoalActivity.this, "Cancelled", Toast.LENGTH_LONG).show();
Intent i = new Intent(GoalActivity.this, ListDataActivity.class);
startActivity(i);
return true;
}
return super.onOptionsItemSelected(item);
}
public void AddData(String name, int pri) {
boolean insertData = mDatabaseHelper.addData(name, pri);
Log.d(TAG,"STAGE 1 addData: Adding " + name);
if (insertData) {
toastMessage("Data Successfully Inserted!");
} else {
toastMessage("Something went wrong");
}
}
private void toastMessage(String message){
Toast.makeText(this,message, Toast.LENGTH_SHORT).show();
}
}
我很感激！