我刚刚创建了我的第一个数据库，但似乎我已经以一种奇怪的方式完成了我创建了一个adapter.java和一个下面显示的activity.java我想知道如何在屏幕上打印数据库信息因为我的所有尝试都失败了。
这是我的Activity Javas
package com.course.ucas;
import android.app.Activity;
import android.os.Bundle;
public class DatabaseActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DBAdapter db = new DBAdapter(this);
db.open();
long id;
id = db.insertTitle(
"UNIVERSITY OF ABERDEEN","Computer Science",310,84,0,"BBB","");
id = db.insertTitle(
"UNIVERSITY OF ABERTAY DUNDEE","Computer Science",300,0,70,"CCC","N/A");
id = db.insertTitle(
"ABERYSTWYTH UNIVERSITY","Computer Science",270,79,70,"BBC","N/A");
id = db.insertTitle(
"ANGLIA RUSKIN UNIVERSITY","Computer Science",220,69,50,"CCC","N/A");
id = db.insertTitle(
"ASTON UNIVERSITY","Computer Science",330,91,80,"BBB","N/A");
id = db.insertTitle(
"BANGOR UNIVERSITY","Computer Science",260,86,0,"CCC","N/A");
id = db.insertTitle(
"UNIVERSITY OF BATH","Computer Science",440,91,100,"AAA","A*AB");
id = db.insertTitle(
"UNIVERSITY OF BEDFORDSHIRE","Computer Science",120,74,50,"CCD","N/A");
id = db.insertTitle(
"UNIVERSITY OF BIRMINGHAM","Computer Science",400,76,90,"AAB","N/A");
id = db.insertTitle(
"BIRMINGHAM CITY UNIVERSITY","Computer Science",240,68,70,"BCC","N/A");
id = db.insertTitle(
"THE UNIVERSITY OF BOLTON","Computer Science",0,78,0,"CCC","N/A");
id = db.insertTitle(
"UNIVERSITY OF BRADFORD","Computer Science",180,72,50,"CCC","N/A");
id = db.insertTitle(
"UNIVERSITY OF BRIGHTON","Computer Science",270,80,69,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF BRISTOL","Computer Science",480,96,95,"AAA","N/A");
id = db.insertTitle(
"THE UNIVERSITY OF BUCKINGHAM","Computer Science",0,0,0,"BBC","N/A");
id = db.insertTitle(
"BUCKINGHAMSHIRE NEW UNIVERSITY","Computer Science",150,61,55,"CCD","N/A");
id = db.insertTitle(
"UNIVERSITY OF CAMBRIDGE","Computer Science",580,95,100,"A*AA","N/A");
id = db.insertTitle(
"CANTERBURY CHRIST CHURCH UNIVERSITY","Computer Science",170,81,45,"CCC","N/A");
id = db.insertTitle(
"CARDIFF UNIVERSITY","Computer Science",360,79,82,"ABB","N/A");
id = db.insertTitle(
"CARDIFF METROPOLITAN UNIVERSITY","Computer Science",200,93,55,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF CENTRAL LANCASHIRE","Computer Science",240,75,74,"CCC","BBC");
id = db.insertTitle(
"UNIVERSITY OF CHESTER","Computer Science",240,86,75,"CCC","N/A");
id = db.insertTitle(
"THE CITY UNIVERSITY","Computer Science",320,65,73,"AAA","N/A");
id = db.insertTitle(
"COVENTRY UNIVERSITY","Computer Science",230,67,65,"BBC","N/A");
id = db.insertTitle(
"THE UNIVERSITY OF CUMBRIA","Computer Science",0,0,0,"CCC","N/A");
id = db.insertTitle(
"DE MONTFORT UNIVERSITY","Computer Science",230,80,58,"AAA","N/A");
id = db.insertTitle(
"UNIVERSITY OF DERBY","Computer Science",260,73,70,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF DUNDEE","Computer Science",336,96,85,"BBB","N/A");
id = db.insertTitle(
"DURHAM UNIVERSITY","Computer Science",440,81,100,"AAA","N/A");
id = db.insertTitle(
"UNIVERSITY OF EAST ANGLIA","Computer Science",320,89,55,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF EAST LONDON","Computer Science",205,74,39,"CDD","N/A");
id = db.insertTitle(
"UNIVERSITY OF EDINBURGH","Computer Science",428,90,85,"AAA","ABB");
id = db.insertTitle(
"EDINBURGH NAPIER UNIVERSITY","Computer Science",260,83,58,"CCD","N/A");
id = db.insertTitle(
"UNIVERSITY OF ESSEX","Computer Science",315,84,75,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF EXETER","Computer Science",0,86,95,"ABB","N/A");
id = db.insertTitle(
"UNIVERSITY OF GLAMORGAN / PRIFYSGOL MORGANNWG","Computer Science",280,69,52,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF GLASGOW","Computer Science",384,98,90,"ABB","N/A");
id = db.insertTitle(
"GLASGOW CALEDONIAN UNIVERSITY","Computer Science",258,80,51,"CC","N/A");
id = db.insertTitle(
"UNIVERSITY OF GLOUCESTERSHIRE","Computer Science",220,73,71,"CCC","N/A");
id = db.insertTitle(
"GLYNDWR UNIVERSITY","Computer Science",200,75,70,"CCC","N/A");
id = db.insertTitle(
"GOLDSMITHS' COLLEGE","Computer Science",220,83,70,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF GREENWICH","Computer Science",180,89,54,"BBC","N/A");
id = db.insertTitle(
"HERIOT-WATT UNIVERSITY","Computer Science",288,77,90,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF HERTFORDSHIRE","Computer Science",180,80,62,"CDD","N/A");
id = db.insertTitle(
"UNIVERSITY OF THE HIGHLANDS AND ISLANDS","Computer Science",0,0,0,"D","N/A");
id = db.insertTitle(
"UNIVERSITY OF HUDDERSFIELD","Computer Science",240,63,84,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF HULL","Computer Science",240,83,95,"BBC","N/A");
id = db.insertTitle(
"IMPERIAL COLLEGE, LONDON","Computer Science",510,84,98,"AAA","N/A");
id = db.insertTitle(
"KEELE UNIVERSITY","Computer Science",260,74,0,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF KENT","Computer Science",310,80,90,"BBB","N/A");
id = db.insertTitle(
"KING'S COLLEGE LONDON","Computer Science",370,82,90,"AAB","N/A");
id = db.insertTitle(
"KINGSTON UNIVERSITY","Computer Science",200,73,68,"BBC","N/A");
id = db.insertTitle(
"LANCASTER UNIVERSITY","Computer Science",380,81,80,"ABB","N/A");
id = db.insertTitle(
"UNIVERSITY OF LEEDS","Computer Science",370,69,90,"AAA","N/A");
id = db.insertTitle(
"LEEDS METROPOLITAN UNIVERSITY","Computer Science",180,71,57,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF LEICESTER","Computer Science",330,92,80,"ABB","N/A");
id = db.insertTitle(
"UNIVERSITY OF LIVERPOOL","Computer Science",360,89,80,"AAB","ABB");
id = db.insertTitle(
"LIVERPOOL HOPE UNIVERSITY","Computer Science",280,78,40,"ABB","N/A");
id = db.insertTitle(
"UNIVERSITY COLLEGE LONDON","Computer Science",430,87,90,"A*AA","N/A");
id = db.insertTitle(
"LONDON METROPOLITAN UNIVERSITY","Computer Science",140,73,55,"ABB","N/A");
id = db.insertTitle(
"LOUGHBOROUGH UNIVERSITY","Computer Science",340,88,88,"ABB","N/A");
id = db.insertTitle(
"THE UNIVERSITY OF MANCHESTER","Computer Science",400,82,83,"AAB","N/A");
id = db.insertTitle(
"THE MANCHESTER METROPOLITAN UNIVERSITY","Computer Science",220,67,66,"CCC","N/A");
id = db.insertTitle(
"MIDDLESEX UNIVERSITY","Computer Science",140,73,50,"CDD","N/A");
id = db.insertTitle(
"NEWCASTLE UNIVERSITY","Computer Science",350,88,90,"ABB","N/A");
id = db.insertTitle(
"THE UNIVERSITY OF NORTHAMPTON","Computer Science",200,75,60,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF NORTHUMBRIA","Computer Science",240,80,77,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF NOTTINGHAM","Computer Science",360,82,90,"BBB","N/A");
id = db.insertTitle(
"NOTTINGHAM TRENT UNIVERSITY","Computer Science",260,69,68,"BBC","N/A");
id = db.insertTitle(
"OXFORD UNIVERSITY","Computer Science",520,0,90,"AAA","N/A");
id = db.insertTitle(
"OXFORD BROOKES UNIVERSITY","Computer Science",260,85,85,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF PLYMOUTH","Computer Science",260,76,75,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF PORTSMOUTH","Computer Science",240,81,72,"BBC","N/A");
id = db.insertTitle(
"QUEEN'S UNIVERSITY BELFAST","Computer Science",320,84,84,"BBB","N/A");
id = db.insertTitle(
"QUEEN MARY, UNIVERSITY OF LONDON","Computer Science",300,88,65,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF READING","Computer Science",350,79,95,"ABB","N/A");
id = db.insertTitle(
"THE ROBERT GORDON UNIVERSITY","Computer Science",240,79,80,"CCC","N/A");
id = db.insertTitle(
"ROYAL HOLLOWAY, UNIVERSITY OF LONDON","Computer Science",320,82,0,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF SALFORD","Computer Science",240,89,75,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF SHEFFIELD","Computer Science",390,83,95,"ABB","N/A");
id = db.insertTitle(
"SHEFFIELD HALLAM UNIVERSITY","Computer Science",240,73,73,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF SOUTHAMPTON","Computer Science",450,92,95,"AAA","N/A");
id = db.insertTitle(
"SOUTHAMPTON SOLENT UNIVERSITY","Computer Science",240,68,85,"CDD","N/A");
id = db.insertTitle(
"STAFFORDSHIRE UNIVERSITY","Computer Science",240,70,78,"CDD","N/A");
id = db.insertTitle(
"UNIVERSITY OF ST ANDREWS","Computer Science",458,90,0,"AAB","N/A");
id = db.insertTitle(
"UNIVERSITY OF STIRLING","Computer Science",255,100,65,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF STRATHCLYDE","Computer Science",333,97,90,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF SUNDERLAND","Computer Science",225,59,70,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF SURREY","Computer Science",380,89,90,"AAB","N/A");
id = db.insertTitle(
"UNIVERSITY OF SUSSEX","Computer Science",360,84,85,"ABB","BBB");
id = db.insertTitle(
"SWANSEA UNIVERSITY","Computer Science",280,82,75,"ABB","N/A");
id = db.insertTitle(
"TEESSIDE UNIVERSITY","Computer Science",260,78,64,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF ULSTER","Computer Science",237,73,63,"BBB","N/A");
id = db.insertTitle(
"UNIVERSITY OF WALES: TRINITY SAINT DAVID","Computer Science",0,77,0,"CDD","N/A");
id = db.insertTitle(
"UNIVERSITY OF WALES, NEWPORT","Computer Science",230,81,50,"CDD","N/A");
id = db.insertTitle(
"UNIVERSITY OF WARWICK","Computer Science",480,87,100,"AAB","N/A");
id = db.insertTitle(
"UNIVERSITY OF THE WEST OF ENGLAND, BRISTOL","Computer Science",240,74,84,"BBB","N/A");
id = db.insertTitle(
"THE UNIVERSITY OF WEST LONDON","Computer Science",0,37,0,"CDD","N/A");
id = db.insertTitle(
"THE UNIVERSITY OF WESTMINSTER","Computer Science",180,54,63,"CCC","AA");
id = db.insertTitle(
"UNIVERSITY OF THE WEST OF SCOTLAND","Computer Science",238,69,52,"BBC","N/A");
id = db.insertTitle(
"UNIVERSITY OF WOLVERHAMPTON","Computer Science",150,70,61,"CCD","N/A");
id = db.insertTitle(
"UNIVERSITY OF WORCESTER","Computer Science",210,65,55,"CCC","N/A");
id = db.insertTitle(
"UNIVERSITY OF YORK","Computer Science",460,91,100,"AAA","N/A");
db.close();
}
}
这是我的databaseAdapter
package com.course.ucas;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DBAdapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_UNIVERSITY = "University";
public static final String KEY_COURSE = "Course";
public static final String KEY_UCAS = "UCAS";
public static final String KEY_SATISFACTION = "Student_Satisfaction";
public static final String KEY_EMPLOYED = "Employed";
public static final String KEY_OFFER = "Offer";
public static final String KEY_OTHER = "Other";
private static final String TAG = "DBAdapter";
private static final String DATABASE_NAME = "UCAS";
private static final String DATABASE_TABLE ="computer";
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_CREATE =
"create table titles (_id integer primary key autoincrement, "
+ "University text not null, Course text not null, UCAS int not null, "
+ "Student Satisfaction int not null, Employed int not null, Offer text not null, Other text not null);";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(DATABASE_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
Log.w(TAG, "Upgrading database from version " + oldVersion
+ " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS titles");
onCreate(db);
}
}
public DBAdapter open() throws SQLException
{
db = DBHelper.getWritableDatabase();
return this;
}
//---closes the database---
public void close()
{
DBHelper.close();
}
//---insert a title into the database---
public long insertTitle(String university, String other, int i, int j,int k, String UCAS, String employed)
{
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_UNIVERSITY, university);
initialValues.put(KEY_COURSE, j);
initialValues.put(KEY_UCAS , UCAS);
initialValues.put(KEY_SATISFACTION, k);
initialValues.put(KEY_EMPLOYED , employed);
initialValues.put(KEY_OFFER , i);
initialValues.put(KEY_OTHER , other);
return db.insert(DATABASE_TABLE, null, initialValues);
}
//---deletes a particular title---
public boolean deleteTitle(long rowId)
{
return db.delete(DATABASE_TABLE, KEY_ROWID +
"=" + rowId, null) > 0;
}
//---retrieves all the titles---
public Cursor getAllTitles()
{
return db.query(DATABASE_TABLE, new String[] {
KEY_ROWID,
KEY_UNIVERSITY,
KEY_COURSE,
KEY_UCAS ,
KEY_SATISFACTION,
KEY_EMPLOYED,
KEY_OFFER,
KEY_OTHER,
},
null,
null,
null,
null,
null);
}
//---retrieves a particular title---
public Cursor getTitle(long rowId) throws SQLException
{
Cursor mCursor =
db.query(true, DATABASE_TABLE, new String[] {
KEY_ROWID,
KEY_UNIVERSITY,
KEY_COURSE,
KEY_UCAS,
KEY_SATISFACTION,
KEY_EMPLOYED,
KEY_OFFER,
KEY_OTHER,
},
KEY_ROWID + "=" + rowId,
null,
null,
null,
null,
null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
//---updates a title---
public boolean updateTitle(long rowID, String university, String other, int i, int j,int k, String UCAS, String employed)
{
ContentValues args = new ContentValues();
args.put(KEY_UNIVERSITY, university);
args.put(KEY_COURSE, i);
args.put(KEY_UCAS , UCAS);
args.put(KEY_SATISFACTION, j);
args.put(KEY_EMPLOYED , employed);
args.put(KEY_OFFER , k);
args.put(KEY_OTHER , other);
return db.update(DATABASE_TABLE, args,
KEY_ROWID + "=" + rowID, null) > 0;
}
}
答案 0 :(得分：0)
嗯，首先你的适配器代码必须正确。您仍然试图从您从未创建的表中插入和查询。
您需要将DATABASE_TABLE字符串更改为＆＃34;标题＆＃34; 或更改您的DATABASE_CREATE字符串以使用＆＃34;计算机＆＃34;而不是＆＃34;标题＆＃34;。
一旦你解决了这个问题，你需要一个光标来拉取数据，然后你可以手动使用光标来获取数据或将其输入ListView。
我建议去开发者网站阅读数据库，游标和ListBiews。实际上，我建议一般在Android上阅读。