Android 数据库简单程序不工作
Android Database simple program not working
我正在使用 SimpleCursorAdapter 开发一个简单的应用程序，但我收到错误 java.lang.IllegalArgumentException: column '_id' does not exist，即使我有一个 id=list 的列表视图。
在 运行 应用程序上，它说，不幸的是数据库已停止。
这是我的代码：
主要活动
package com.example.ayushi.database;
import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
public class MainActivity extends Activity {
EditText text1,text2;
DatabaseHelper dbHelp;
ListView alist;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text1 = (EditText) findViewById(R.id.EText1);
text2 = (EditText) findViewById(R.id.EText2);
dbHelp = new DatabaseHelper(this);
alist = (ListView) findViewById(R.id.newlist);
// alist = getListView();
getData();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void addNew(View view) {
String s1 = text1.getText().toString();
String s2 = text2.getText().toString();
dbHelp.addData(s1,s2);
getData();
}
public void getData()
{
Cursor cursor = dbHelp.fetchData();
ListAdapter myAdapter = new SimpleCursorAdapter(this,R.layout.tasks,
cursor,
new String[]{dbHelp._ID,dbHelp.COLUMN_1,dbHelp.COLUMN_2},
new int[]{R.id.idnum,R.id.c1,R.id.c2},0);
alist.setAdapter(myAdapter);
}
}
数据库助手
package com.example.ayushi.database;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME="DbApp";
public static final int DATABASE_VERSION=1;
public static final String TABLE = "DbTable";
public static final String _ID = "id";
public static final String COLUMN_1="Task";
public static final String COLUMN_2="status";
public static final String CREATE_TABLE="CREATE TABLE "
+ TABLE + " ( "
+ _ID + " INTEGER PRIMARY KEY, "
+ COLUMN_1 + " TEXT, "
+ COLUMN_2 + " TEXT)";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public void addData(String s1,String s2)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COLUMN_1,s1);
values.put(COLUMN_2,s2);
db.insert(TABLE,null,values);
db.close();
}
public Cursor fetchData()
{
SQLiteDatabase db = this.getReadableDatabase();
return db.query(TABLE,
new String[]{_ID,COLUMN_1,COLUMN_2},
null, null, null, null, null);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE);
onCreate(db);
}
}
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<TextView android:text="@string/hello_world"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/AppName"/>
<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:hint="@string/input1"
android:layout_below="@+id/AppName"
android:id="@+id/EText1"/>
<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:hint="@string/input2"
android:layout_below="@+id/EText1"
android:id="@+id/EText2"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/EText2"
android:text="@string/submit"
android:onClick="addNew"
android:id="@+id/button"
/>
<ListView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/newlist"
android:layout_below="@+id/button">
</ListView>
</RelativeLayout>
tasks.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/idnum"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/c1"
android:layout_below="@+id/idnum"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/c2"
android:layout_below="@+id/c1"/>
</RelativeLayout>
LogCat:
03-25 19:02:08.320 31391-31391/com.example.ayushi.database D/dalvikvm﹕ Zygote::ForkAndSpecialize : 0
03-25 19:02:08.321 31391-31391/com.example.ayushi.database D/dalvikvm﹕ zygote get new systemTid : 31391
03-25 19:02:08.321 31391-31391/com.example.ayushi.database D/dalvikvm﹕ Late-enabling CheckJNI
03-25 19:02:08.324 31391-31391/com.example.ayushi.database D/jdwp﹕ prepping for JDWP over ADB
03-25 19:02:08.324 31391-31391/com.example.ayushi.database D/jdwp﹕ ADB transport startup
03-25 19:02:08.325 31391-31397/com.example.ayushi.database D/dalvikvm﹕ Elevating priority from 0 to -8
03-25 19:02:08.325 31391-31398/com.example.ayushi.database D/jdwp﹕ JDWP: thread running
03-25 19:02:08.326 31391-31398/com.example.ayushi.database D/jdwp﹕ acceptConnection
03-25 19:02:08.326 31391-31398/com.example.ayushi.database D/jdwp﹕ trying to receive file descriptor from ADB
03-25 19:02:08.327 31391-31391/com.example.ayushi.database D/dalvikvm﹕ zygote get thread init done
03-25 19:02:08.375 31391-31391/com.example.ayushi.database W/asset﹕ AssetManager-->addDefaultAssets CIP path not exsit!
03-25 19:02:08.380 31391-31391/com.example.ayushi.database W/ActivityThread﹕ Application com.example.ayushi.database is waiting for the debugger on port 8100...
03-25 19:02:08.386 31391-31391/com.example.ayushi.database I/System.out﹕ Sending WAIT chunk
03-25 19:02:08.407 31391-31398/com.example.ayushi.database D/jdwp﹕ received file descriptor 44 from ADB
03-25 19:02:08.436 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.437 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.437 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x13, id=0x40000101, flags=0x0, dataLen=0x8
03-25 19:02:08.443 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.443 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x17, id=0x40000102, flags=0x0, dataLen=0xC
03-25 19:02:08.445 31391-31398/com.example.ayushi.database D/jdwp﹕ sendBufferedRequest : len=0x14
03-25 19:02:08.446 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.446 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x13, id=0x40000103, flags=0x0, dataLen=0x8
03-25 19:02:08.448 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.448 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x13, id=0x40000104, flags=0x0, dataLen=0x8
03-25 19:02:08.448 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.448 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x14, id=0x40000105, flags=0x0, dataLen=0x9
03-25 19:02:08.453 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.453 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x7, cmdSet=0x1, len=0xB, id=0x97, flags=0x0, dataLen=0x0
03-25 19:02:08.453 31391-31398/com.example.ayushi.database I/dalvikvm﹕ Debugger is active
03-25 19:02:08.470 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.470 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xF, len=0x11, id=0x99, flags=0x0, dataLen=0x6
03-25 19:02:08.475 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.475 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xF, len=0x11, id=0x9B, flags=0x0, dataLen=0x6
03-25 19:02:08.586 31391-31391/com.example.ayushi.database I/System.out﹕ Debugger has connected
03-25 19:02:08.586 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=111
03-25 19:02:08.587 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:08.632 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.632 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0x1, len=0xB, id=0x9D, flags=0x0, dataLen=0x0
03-25 19:02:08.669 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.669 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x11, cmdSet=0x1, len=0xB, id=0x9F, flags=0x0, dataLen=0x0
03-25 19:02:08.692 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.692 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0xC, cmdSet=0x1, len=0xB, id=0xA1, flags=0x0, dataLen=0x0
03-25 19:02:08.694 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.694 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x14, cmdSet=0x1, len=0xB, id=0xA3, flags=0x0, dataLen=0x0
03-25 19:02:08.787 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=84
03-25 19:02:08.787 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:08.987 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=284
03-25 19:02:08.987 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.022 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:09.022 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x5, cmdSet=0x1, len=0xB, id=0xA5, flags=0x0, dataLen=0x0
03-25 19:02:09.024 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:09.024 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xF, len=0x11, id=0xA7, flags=0x0, dataLen=0x6
03-25 19:02:09.029 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:09.029 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xF, len=0x11, id=0xA9, flags=0x0, dataLen=0x6
03-25 19:02:09.187 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=159
03-25 19:02:09.187 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.388 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=359
03-25 19:02:09.388 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.588 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=559
03-25 19:02:09.588 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.788 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=760
03-25 19:02:09.788 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.989 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=960
03-25 19:02:09.989 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:10.189 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=1160
03-25 19:02:10.189 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:10.389 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=1361
03-25 19:02:10.390 31391-31391/com.example.ayushi.database I/System.out﹕ debugger has settled (1361)
03-25 19:02:10.401 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x58
03-25 19:02:10.427 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x53
03-25 19:02:10.428 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x4B
03-25 19:02:10.453 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x57
03-25 19:02:10.453 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x62
03-25 19:02:10.470 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x5C
03-25 19:02:10.487 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x43
03-25 19:02:10.503 31391-31391/com.example.ayushi.database D/AbsListView﹕ checkAbsListViewlLogProperty get invalid command
03-25 19:02:10.507 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x5A
03-25 19:02:10.528 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x54
03-25 19:02:10.528 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x52
03-25 19:02:10.529 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x53
03-25 19:02:10.531 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x5B
03-25 19:02:10.531 31391-31391/com.example.ayushi.database D/AndroidRuntime﹕ Shutting down VM
03-25 19:02:10.531 31391-31391/com.example.ayushi.database W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x40cf29a8)
03-25 19:02:10.551 31391-31391/com.example.ayushi.database E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ayushi.database/com.example.ayushi.database.MainActivity}: java.lang.IllegalArgumentException: column '_id' does not exist
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2343)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
at android.app.ActivityThread.access0(ActivityThread.java:162)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5371)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:303)
at android.widget.CursorAdapter.init(CursorAdapter.java:168)
at android.widget.CursorAdapter.<init>(CursorAdapter.java:145)
at android.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:91)
at android.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:104)
at com.example.ayushi.database.MainActivity.getData(MainActivity.java:65)
at com.example.ayushi.database.MainActivity.onCreate(MainActivity.java:29)
at android.app.Activity.performCreate(Activity.java:5122)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
at android.app.ActivityThread.access0(ActivityThread.java:162) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)at android.app.ActivityThread.main(ActivityThread.java:5371)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) at dalvik.system.NativeStart.main(Native Method)
03-25 19:02:13.148 31391-31391/com.example.ayushi.database I/Process﹕ Sending signal. PID: 31391 SIG: 9
编辑：在原始问题中，错误是：符号变量列表不存在。
java.lang.IllegalArgumentException: column '_id' does not exist
当您查询数据时会发生这种情况，在本例中，它是您的 fetchData() 方法。
尝试这样的事情：
public Cursor fetchData() {
String getData = ("SELECT id as _id, Task, status FROM DbTable);
return db.rawQuery(getData,null);
}
或
public Cursor fetchData() {
String getData = ("SELECT * FROM DbTable);
return db.rawQuery(getData,null);
}
您可以参考以下链接以获得进一步的解释：
Link 1 Link 2 and Link 3
希望对您有所帮助！祝你好运！ :)
尝试将 DatabaseHelper class 中的 public static final String _ID = "id"; 替换为 public static final String _ID = "_id";
或者如@Angeline 所说编写自定义查询。
我正在使用 SimpleCursorAdapter 开发一个简单的应用程序，但我收到错误 java.lang.IllegalArgumentException: column '_id' does not exist，即使我有一个 id=list 的列表视图。
在 运行 应用程序上，它说，不幸的是数据库已停止。
这是我的代码：
主要活动
package com.example.ayushi.database;
import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
public class MainActivity extends Activity {
EditText text1,text2;
DatabaseHelper dbHelp;
ListView alist;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text1 = (EditText) findViewById(R.id.EText1);
text2 = (EditText) findViewById(R.id.EText2);
dbHelp = new DatabaseHelper(this);
alist = (ListView) findViewById(R.id.newlist);
// alist = getListView();
getData();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void addNew(View view) {
String s1 = text1.getText().toString();
String s2 = text2.getText().toString();
dbHelp.addData(s1,s2);
getData();
}
public void getData()
{
Cursor cursor = dbHelp.fetchData();
ListAdapter myAdapter = new SimpleCursorAdapter(this,R.layout.tasks,
cursor,
new String[]{dbHelp._ID,dbHelp.COLUMN_1,dbHelp.COLUMN_2},
new int[]{R.id.idnum,R.id.c1,R.id.c2},0);
alist.setAdapter(myAdapter);
}
}
数据库助手
package com.example.ayushi.database;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME="DbApp";
public static final int DATABASE_VERSION=1;
public static final String TABLE = "DbTable";
public static final String _ID = "id";
public static final String COLUMN_1="Task";
public static final String COLUMN_2="status";
public static final String CREATE_TABLE="CREATE TABLE "
+ TABLE + " ( "
+ _ID + " INTEGER PRIMARY KEY, "
+ COLUMN_1 + " TEXT, "
+ COLUMN_2 + " TEXT)";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public void addData(String s1,String s2)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COLUMN_1,s1);
values.put(COLUMN_2,s2);
db.insert(TABLE,null,values);
db.close();
}
public Cursor fetchData()
{
SQLiteDatabase db = this.getReadableDatabase();
return db.query(TABLE,
new String[]{_ID,COLUMN_1,COLUMN_2},
null, null, null, null, null);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE);
onCreate(db);
}
}
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">
<TextView android:text="@string/hello_world"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/AppName"/>
<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:hint="@string/input1"
android:layout_below="@+id/AppName"
android:id="@+id/EText1"/>
<EditText
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:hint="@string/input2"
android:layout_below="@+id/EText1"
android:id="@+id/EText2"/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/EText2"
android:text="@string/submit"
android:onClick="addNew"
android:id="@+id/button"
/>
<ListView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/newlist"
android:layout_below="@+id/button">
</ListView>
</RelativeLayout>
tasks.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent" android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/idnum"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/c1"
android:layout_below="@+id/idnum"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/c2"
android:layout_below="@+id/c1"/>
</RelativeLayout>
LogCat:
03-25 19:02:08.320 31391-31391/com.example.ayushi.database D/dalvikvm﹕ Zygote::ForkAndSpecialize : 0
03-25 19:02:08.321 31391-31391/com.example.ayushi.database D/dalvikvm﹕ zygote get new systemTid : 31391
03-25 19:02:08.321 31391-31391/com.example.ayushi.database D/dalvikvm﹕ Late-enabling CheckJNI
03-25 19:02:08.324 31391-31391/com.example.ayushi.database D/jdwp﹕ prepping for JDWP over ADB
03-25 19:02:08.324 31391-31391/com.example.ayushi.database D/jdwp﹕ ADB transport startup
03-25 19:02:08.325 31391-31397/com.example.ayushi.database D/dalvikvm﹕ Elevating priority from 0 to -8
03-25 19:02:08.325 31391-31398/com.example.ayushi.database D/jdwp﹕ JDWP: thread running
03-25 19:02:08.326 31391-31398/com.example.ayushi.database D/jdwp﹕ acceptConnection
03-25 19:02:08.326 31391-31398/com.example.ayushi.database D/jdwp﹕ trying to receive file descriptor from ADB
03-25 19:02:08.327 31391-31391/com.example.ayushi.database D/dalvikvm﹕ zygote get thread init done
03-25 19:02:08.375 31391-31391/com.example.ayushi.database W/asset﹕ AssetManager-->addDefaultAssets CIP path not exsit!
03-25 19:02:08.380 31391-31391/com.example.ayushi.database W/ActivityThread﹕ Application com.example.ayushi.database is waiting for the debugger on port 8100...
03-25 19:02:08.386 31391-31391/com.example.ayushi.database I/System.out﹕ Sending WAIT chunk
03-25 19:02:08.407 31391-31398/com.example.ayushi.database D/jdwp﹕ received file descriptor 44 from ADB
03-25 19:02:08.436 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.437 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.437 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x13, id=0x40000101, flags=0x0, dataLen=0x8
03-25 19:02:08.443 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.443 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x17, id=0x40000102, flags=0x0, dataLen=0xC
03-25 19:02:08.445 31391-31398/com.example.ayushi.database D/jdwp﹕ sendBufferedRequest : len=0x14
03-25 19:02:08.446 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.446 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x13, id=0x40000103, flags=0x0, dataLen=0x8
03-25 19:02:08.448 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.448 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x13, id=0x40000104, flags=0x0, dataLen=0x8
03-25 19:02:08.448 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.448 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xC7, len=0x14, id=0x40000105, flags=0x0, dataLen=0x9
03-25 19:02:08.453 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.453 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x7, cmdSet=0x1, len=0xB, id=0x97, flags=0x0, dataLen=0x0
03-25 19:02:08.453 31391-31398/com.example.ayushi.database I/dalvikvm﹕ Debugger is active
03-25 19:02:08.470 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.470 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xF, len=0x11, id=0x99, flags=0x0, dataLen=0x6
03-25 19:02:08.475 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.475 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xF, len=0x11, id=0x9B, flags=0x0, dataLen=0x6
03-25 19:02:08.586 31391-31391/com.example.ayushi.database I/System.out﹕ Debugger has connected
03-25 19:02:08.586 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=111
03-25 19:02:08.587 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:08.632 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.632 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0x1, len=0xB, id=0x9D, flags=0x0, dataLen=0x0
03-25 19:02:08.669 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.669 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x11, cmdSet=0x1, len=0xB, id=0x9F, flags=0x0, dataLen=0x0
03-25 19:02:08.692 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.692 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0xC, cmdSet=0x1, len=0xB, id=0xA1, flags=0x0, dataLen=0x0
03-25 19:02:08.694 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:08.694 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x14, cmdSet=0x1, len=0xB, id=0xA3, flags=0x0, dataLen=0x0
03-25 19:02:08.787 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=84
03-25 19:02:08.787 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:08.987 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=284
03-25 19:02:08.987 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.022 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:09.022 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x5, cmdSet=0x1, len=0xB, id=0xA5, flags=0x0, dataLen=0x0
03-25 19:02:09.024 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:09.024 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xF, len=0x11, id=0xA7, flags=0x0, dataLen=0x6
03-25 19:02:09.029 31391-31398/com.example.ayushi.database D/jdwp﹕ processIncoming
03-25 19:02:09.029 31391-31398/com.example.ayushi.database D/jdwp﹕ handlePacket : cmd=0x1, cmdSet=0xF, len=0x11, id=0xA9, flags=0x0, dataLen=0x6
03-25 19:02:09.187 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=159
03-25 19:02:09.187 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.388 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=359
03-25 19:02:09.388 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.588 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=559
03-25 19:02:09.588 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.788 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=760
03-25 19:02:09.788 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:09.989 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=960
03-25 19:02:09.989 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:10.189 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=1160
03-25 19:02:10.189 31391-31391/com.example.ayushi.database I/System.out﹕ waiting for debugger to settle...
03-25 19:02:10.389 31391-31391/com.example.ayushi.database D/jdwp﹕ +++ debugger interval=1361
03-25 19:02:10.390 31391-31391/com.example.ayushi.database I/System.out﹕ debugger has settled (1361)
03-25 19:02:10.401 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x58
03-25 19:02:10.427 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x53
03-25 19:02:10.428 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x4B
03-25 19:02:10.453 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x57
03-25 19:02:10.453 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x62
03-25 19:02:10.470 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x5C
03-25 19:02:10.487 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x43
03-25 19:02:10.503 31391-31391/com.example.ayushi.database D/AbsListView﹕ checkAbsListViewlLogProperty get invalid command
03-25 19:02:10.507 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x5A
03-25 19:02:10.528 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x54
03-25 19:02:10.528 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x52
03-25 19:02:10.529 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x53
03-25 19:02:10.531 31391-31391/com.example.ayushi.database D/jdwp﹕ sendRequest : Len=0x5B
03-25 19:02:10.531 31391-31391/com.example.ayushi.database D/AndroidRuntime﹕ Shutting down VM
03-25 19:02:10.531 31391-31391/com.example.ayushi.database W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x40cf29a8)
03-25 19:02:10.551 31391-31391/com.example.ayushi.database E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ayushi.database/com.example.ayushi.database.MainActivity}: java.lang.IllegalArgumentException: column '_id' does not exist
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2343)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
at android.app.ActivityThread.access0(ActivityThread.java:162)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5371)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:303)
at android.widget.CursorAdapter.init(CursorAdapter.java:168)
at android.widget.CursorAdapter.<init>(CursorAdapter.java:145)
at android.widget.ResourceCursorAdapter.<init>(ResourceCursorAdapter.java:91)
at android.widget.SimpleCursorAdapter.<init>(SimpleCursorAdapter.java:104)
at com.example.ayushi.database.MainActivity.getData(MainActivity.java:65)
at com.example.ayushi.database.MainActivity.onCreate(MainActivity.java:29)
at android.app.Activity.performCreate(Activity.java:5122)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
at android.app.ActivityThread.access0(ActivityThread.java:162) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)at android.app.ActivityThread.main(ActivityThread.java:5371)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) at dalvik.system.NativeStart.main(Native Method)
03-25 19:02:13.148 31391-31391/com.example.ayushi.database I/Process﹕ Sending signal. PID: 31391 SIG: 9
编辑：在原始问题中，错误是：符号变量列表不存在。
java.lang.IllegalArgumentException: column '_id' does not exist
当您查询数据时会发生这种情况，在本例中，它是您的 fetchData() 方法。 尝试这样的事情：
public Cursor fetchData() {
String getData = ("SELECT id as _id, Task, status FROM DbTable);
return db.rawQuery(getData,null);
}
或
public Cursor fetchData() {
String getData = ("SELECT * FROM DbTable);
return db.rawQuery(getData,null);
}
您可以参考以下链接以获得进一步的解释：
Link 1 Link 2 and Link 3
希望对您有所帮助！祝你好运！ :)
尝试将 DatabaseHelper class 中的 public static final String _ID = "id"; 替换为 public static final String _ID = "_id";
或者如@Angeline 所说编写自定义查询。