NullPointerException openOrCreateDatabase Android [英] NullPointerException openOrCreateDatabase Android

问题描述

我在打开数据库时在我的 EhActivity 类中得到 NullPointerException

i m gettin a NullPointerException in my EhActivity class while opening a database

 public class EHActivity extends Activity {
ArrayList<String>ques= new ArrayList<String>();
 ArrayList<String>ans=new ArrayList<String>();
 SQLiteDatabase db2;

  public ArrayList<String> getQues()
  {
   db2=openOrCreateDatabase("interview.db", MODE_PRIVATE, null);
   db2.execSQL("create table eh (qid int primary key,ques varchar,ans char)");
       db2.execSQL("insert into subject values(1,'What is an exception?','A1 '))");
   db2.execSQL("insert into subject values(2,'What is error?','A2 '))");
       Cursor c=db2.rawQuery("select * from eh",null);
   while(c.moveToNext())
   {
    ques.add(c.getString(1));
   }
   return ques;
  }
 }

日志猫视图是:

03-21 14:06:15.910: E/AndroidRuntime(955): java.lang.NullPointerException03-21 14:06:15.910: E/AndroidRuntime(955): 在 android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203)03-21 14:06:15.910: E/AndroidRuntime(955): at interview.android.EHActivity.getQues(EHActivity.java:19)

03-21 14:06:15.910: E/AndroidRuntime(955): java.lang.NullPointerException 03-21 14:06:15.910: E/AndroidRuntime(955): at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203) 03-21 14:06:15.910: E/AndroidRuntime(955): at interview.android.EHActivity.getQues(EHActivity.java:19)

推荐答案

尽量不要发送 null..openOrCreateDatabase 有另一种方法用于此..

try not sending null.. openOrCreateDatabase has another method for this..

db2=openOrCreateDatabase("interview.db", MODE_PRIVATE);

或

openDatabase("interview.db", MODE_PRIVATE, SQLiteDatabase.CREATE_IF_NECESSARY)

这篇关于NullPointerException openOrCreateDatabase Android的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！