我的Android SQLite数据库存在多个问题。我是自己开发和学习的新手。所以请使用laymens术语，并假设我不知道你在说什么哈哈。具体来说，我遇到了方法问题：
如果您发现任何其他错误，我会接受反馈。感谢您提供的所有帮助。这是我的数据库代码
package com.swavey.testing;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.provider.BaseColumns;
import android.security.KeyChain;
import java.util.Date;
/**
* Created by Adrian on 11/5/2014.
*/
public class smsDatabase {
private static final String KEY_ID = "_id";
private static final int COLUMN_ID =0;
// database info
public static final String DATABASE_NAME = "texts";
public static final String DATABASE_TABLE = "mainTable";
public static final int DATABASE_VERSION = 4;
// list of fields
public static final String KEY_ADDRESS = "address";
public static final String KEY_BODY = "body";
private static final String KEY_DATE = "date";
private static final String KEY_READ = "read";
private static final String KEY_THREADID = "thread_id";
private static final String KEY_TYPE = "type";
private static final String KEY_SEEN = "seen";
//list of field numbers
private static final int COL_ADDRESS = 1;
private static final int COL_BODY = 2;
private static final int COL_DATE = 3;
private static final int COL_READ = 4;
private static final int COL_THREADID = 5;
private static final int COL_TYPE = 6;
private static final int COL_SEEN = 7;
//create string array of all fields;
public static final String[] ALL_KEYS = new String[] {KEY_ID, KEY_ADDRESS, KEY_BODY, KEY_DATE,
KEY_READ, KEY_THREADID, KEY_TYPE, KEY_SEEN};
private static final String DATABASE_CREATE_SQL = "create table " + DATABASE_TABLE
+ " (" + KEY_ID + " integer primary key autoincrement, "
+KEY_ADDRESS + " text not null, "
+KEY_BODY + " text not null, "
+KEY_DATE + " text not null, "
+KEY_READ+ " text not null, "
+KEY_THREADID+ " text not null, "
+KEY_TYPE+ " text not null, "
+KEY_SEEN+ " text not null"
+ ");";
private final Context context;
private DatabaseHelper dbHelper;
private SQLiteDatabase db;
public smsDatabase (Context cxt) {
this.context = cxt;
dbHelper = new DatabaseHelper(context);
}
//open database
public void open() {
db = dbHelper.getWritableDatabase();
}
//close database
public void close() {
dbHelper.close();
}
//returns a cursor with all rows loaded
public Cursor getAllRows() {
String where = null;
Cursor cursor = db.query(true, DATABASE_TABLE, ALL_KEYS, where, null, null, null,
null, null);
if (cursor != null) {
cursor.moveToFirst();
}
return cursor;
}
public boolean isEmpty() {
String where = null;
Cursor cursor = db.query(true, DATABASE_TABLE, ALL_KEYS, where, null, null, null,
null, null);
if (cursor!=null) return false;
return true;
}
// insert sms into table
public long insertSMS (SMS sms) {
ContentValues iv = new ContentValues();
iv.put(KEY_ADDRESS, sms.getAddress());
iv.put(KEY_BODY, sms.getBody());
iv.put(KEY_DATE, sms.getDate());
iv.put(KEY_READ, sms.getRead());
iv.put(KEY_THREADID, sms.getThread_id());
iv.put(KEY_TYPE, sms.getType());
iv.put(KEY_SEEN, sms.getSeen());
return db.insert(DATABASE_TABLE, null, iv);
}
public Cursor getLast() {
SMS txt = new SMS();
String where = null;
Cursor c = db.query(true, DATABASE_TABLE,ALL_KEYS, where, null, null, null, null, null);
c.moveToLast();
return c;
}
public void deleteLast() {
String where = null;
Cursor c = db.query(true, DATABASE_TABLE,ALL_KEYS, where, null, null, null, null, null);
String las = Integer.toString(c.getCount());
db.delete(DATABASE_TABLE, KEY_ID + "=" + las, null);
}
public void deleteRow(String address, String date, String body ) {
db.delete(DATABASE_TABLE, KEY_ADDRESS + "=" + address +" and " + KEY_DATE + "=" +
date + " and " + KEY_BODY + "=" + body, null);
}
public String getLatestSubjectForContact() {
Cursor c = getLast();
String sub = c.getString(c.getColumnIndex("body"));
if (sub.length() > 30) {
sub = sub.substring(0, 30) + "...";
return sub;
}
sub = sub + "...";
return sub;
}
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public void onCreate(SQLiteDatabase _db) {
_db.execSQL(DATABASE_CREATE_SQL);
}
public void onUpgrade(SQLiteDatabase _db, int oldVersion, int newVersion) {
_db.execSQL("DROP TABLE IF EXISTS "+ DATABASE_TABLE);
onCreate(_db);
}
}
}
getLast（）方法的logcat：
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.swavey.testing/com.swavey.testing.MainActivity}: java.lang.IllegalStateException: Couldn't read row 23, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalStateException: Couldn't read row 23, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.database.CursorWindow.nativeGetString(Native Method)
at android.database.CursorWindow.getString(CursorWindow.java:434)
at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:51)
at com.swavey.testing.MainActivity.addText(MainActivity.java:144)
at com.swavey.testing.MainActivity.initialSync(MainActivity.java:105)
at com.swavey.testing.MainActivity.Sync(MainActivity.java:71)
at com.swavey.testing.MainActivity.onCreate(MainActivity.java:41)
at android.app.Activity.performCreate(Activity.java:5008)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
试试这个：
public Cursor getLast() {
SMS txt = new SMS();
String query = "SELECT * FROM mainTable";
Cursor c = db.rawQuery(query, null);
if(c != null && c.getCount() > 1)
return c.moveToLast();
return null;
}
public void deleteLast() {
String query = "SELECT KEY_ID from mainTable order by KEY_ID DESC limit 1";
long lastId = -1;
Cursor c = db.rawQuery(query, null);
if (c != null && c.moveToFirst()) {
lastId = c.getLong(0);
}
if(lastId != -1)
db.delete(DATABASE_TABLE, KEY_ID + "=" + lastId, null);
}