NullPointerException异常openOrCreateDatabase的Android [英] NullPointerException openOrCreateDatabase Android
问题描述
我M在我EhActivity类刚开一个NullPointerException异常而打开数据库
公共类EHActivity延伸活动{
ArrayList的<串GT;疑问句=新的ArrayList<串GT;();
ArrayList的<串GT; ANS =新的ArrayList<串GT;();
SQLiteDatabase DB2; 公众的ArrayList<串GT; getQues()
{
DB2 = openOrCreateDatabase(interview.db,MODE_PRIVATE,NULL);
db2.execSQL(CREATE TABLE诶(QID INT主键,疑问句VARCHAR,ANS字符));
db2.execSQL(插入主题值(1,'什么是例外?','A1')));
db2.execSQL(插入主题值(2,什么是错误?','A2')));
光标C = db2.rawQuery(从EH选择*,NULL);
而(c.moveToNext())
{
ques.add(c.getString(1));
}
返回疑问句;
}
}
日志猫的观点是:
14 03-21:06:15.910:E / AndroidRuntime(955):显示java.lang.NullPointerException
03-21 14:06:15.910:E / AndroidRuntime(955):在android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203)
03-21 14:06:15.910:E / AndroidRuntime(955):在interview.android.EHActivity.getQues(EHActivity.java:19)
块引用>解决方案尽量不要发送空..
openOrCreateDatabase有此的另一种方法。DB2 = openOrCreateDatabase(interview.db,MODE_PRIVATE);
或
的openDatabase(interview.db,MODE_PRIVATE,SQLiteDatabase.CREATE_IF_NECESSARY)
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; } }
log cat view is:
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)
解决方案try not sending null.. openOrCreateDatabase has another method for this..
db2=openOrCreateDatabase("interview.db", MODE_PRIVATE);
or
openDatabase("interview.db", MODE_PRIVATE, SQLiteDatabase.CREATE_IF_NECESSARY)
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