数据没有gettting在Android应用中插入表中

Question

我需要在表中插入一些数据，但是当我在表中插入数据时，我在db.insert（Table_Name，null，cm）处得到空指针异常，声明，我无法解决。请帮助。提前感谢。

package com.example.movietrivia; 

import java.util.ArrayList; 
import java.util.List; 

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteDatabase.CursorFactory; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.util.Log; 

public class QuizHelper extends SQLiteOpenHelper { 

public static final String Db_Name="Movie.db"; 
public static final String Table_Name="MovieTrivia"; 
public static int Version_Number=1; 
public static final String Key_Id="Id"; 
public static final String key_quest="question"; 
public static final String key_ans="Answer"; 
public static final String key_opta="OPTA"; 
public static final String key_optb="OPTB"; 
public static final String key_optc="OPTC"; 
public static final String key_optd="OPTD"; 
private SQLiteDatabase db; 
public QuizHelper(Context context) { 
    super(context, Db_Name, null, Version_Number); 

    // this.db = this.getWritableDatabase(); 
    // TODO Auto-generated constructor stub 
} 
//"Create Table " + table_name + "(" + Col_Name + " TEXT , " + COL_Age + " TEXT)"; 
@Override 
public void onCreate(SQLiteDatabase d) { 
    // TODO Auto-generated method stub 



    String query="Create Table " + Table_Name + " (" 
      + Key_Id + " INTEGER PRIMARY KEY," + key_quest + " TEXT," 
      + key_ans + " TEXT," 
      + key_opta + " TEXT," 
      + key_optb + " TEXT," 
      + key_optc + " TEXT," 
      + key_optd + " TEXT" 
      + ");"; 
    d.execSQL(query); 
    Log.d("Query",query); 
    addQuestion(); 
    //Log.d("Query",query); 
} 
private void addQuestion() 
{ 
    this.getWritableDatabase(); 
    Question q1=new Question("Who is Jack Sparrow in Pirates of 
    Carribean??","dfd","dsdsd","sd","Johnny Depp","D"); 
    Log.d("Here","Where"); 
    this.addQuestions(q1); 
    Question q2=new Question("Who plays batman in Dark Knight??","dfd","Christian 
    Bale","jmjjm","dffdfdfd","B"); 
    this.addQuestions(q2); 
    Question q3=new Question("Who pLays Iron Man in the Series??","Robert Downey 
    Jr.","fdfd","nbnbnb","trrrt","A"); 
    this.addQuestions(q3); 
} 
public void addQuestions(Question quest) 

{ 
    //this.getWritableDatabase(); 
    Log.d("Test","Testing"); 
    Log.d("key_quest",quest.getQuestions()); 
    ContentValues cm=new ContentValues(); 
    Log.d("key_quest",quest.getQuestions()); 
    Log.d("key_ans",quest.getAnswer()); 
    Log.d("key_opta",quest.getOPTA()); 
    Log.d("key_optb",quest.getOPTB()); 
    Log.d("key_optc",quest.getOPTC()); 
    Log.d("key_optd",quest.getOPTD()); 
    cm.put(key_quest,quest.getQuestions()); 
    cm.put(key_ans,quest.getAnswer()); 
    cm.put(key_opta,quest.getOPTA()); 
    cm.put(key_optb,quest.getOPTB()); 
    cm.put(key_optc,quest.getOPTC()); 
    cm.put(key_optd,quest.getOPTD()); 
    db.insert(Table_Name,null,cm); 
} 

public List<Question> getAllQuestion() 
{ 
    List<Question> quest=new ArrayList<Question>(); 
    String selectQuery="Select * from " + Table_Name; 
    SQLiteDatabase db; 
    db=this.getReadableDatabase(); 
    Cursor cursor=db.rawQuery(selectQuery, null); 

     if(cursor.moveToFirst()) 
    { 
     do{ 
      Question ques=new Question(); 
      ques.setId(cursor.getInt(0)); 
      ques.setQuestions(cursor.getString(1)); 
      ques.setAnswer(cursor.getString(2)); 
      ques.setOPTA(cursor.getString(3)); 
      ques.setOPTB(cursor.getString(4)); 
      ques.setOPTC(cursor.getString(5)); 
      ques.setOPTD(cursor.getString(6)); 
     }while(cursor.moveToNext()); 

    } 
    return quest; 
} 
public int rowcount() 
{ 
int row=0; 
String selectQuery = "SELECT * FROM " + Table_Name; 
SQLiteDatabase db = this.getWritableDatabase(); 
Cursor cursor = db.rawQuery(selectQuery, null); 
row=cursor.getCount(); 
return row; 
} 
@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    // TODO Auto-generated method stub 

} 

} 

Answer 1

你打电话getWritableDatabase()递归addQuestion()由onCreate()这又是getWritableDatbase()触发调用。

要么删除addQuestion()呼叫，要么传入SQLiteDatabase作为参数从onCreate()开始工作。