这是主要活动
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
EditText myinput;
TextView mytext;
MyDBHandler dbhandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myinput =(EditText) findViewById(R.id.myinput);
mytext =(TextView) findViewById(R.id.mytext);
dbhandler= new MyDBHandler(this, null, null, 1);
printDatabase();
}
//add product to database
public void addstuff(View view)
{
products product = new products(myinput.getText().toString());
dbhandler.addProduct(product);
printDatabase();
}
//delete items from database
public void deletestuff(View view)
{
String inputtext= myinput.getText().toString();
dbhandler.deleteProduct(inputtext);
printDatabase();
}
public void printDatabase()
{
String dbString= dbhandler.databaseToString();
mytext.setText(dbString);
myinput.setText("");
}
}
产品类，获取和设置产品
public class products {
private int _id;
private String _productname;
public products()
{
}
public products(String productname) {
this._productname = productname;
}
public void set_id(int _id) {
this._id = _id;
}
public void set_productname(String _productname) {
this._productname = _productname;
}
public int get_id() {
return _id;
}
public String get_productname() {
return _productname;
}
}
数据库处理程序类
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.Cursor;
import android.content.Context;
import android.content.ContentValues;
public class MyDBHandler extends SQLiteOpenHelper{
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "products.db";
public static final String TABLE_PRODUCTS = "products";
public static final String COLUMN_ID ="_id";
public static final String COLUMN_PRODUCTNAME ="productname";
public MyDBHandler(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, DATABASE_NAME, factory, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String query= "CREATE TABLE " + TABLE_PRODUCTS + "(" +
COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT , " +
COLUMN_PRODUCTNAME + " TEXT " +
");";
db.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS "+TABLE_PRODUCTS);
onCreate(db);
}
//add a new row to the database
public void addProduct(products product)
{
ContentValues values = new ContentValues();
values.put(COLUMN_PRODUCTNAME, product.get_productname());
SQLiteDatabase db= getWritableDatabase();
db.insert(TABLE_PRODUCTS, null, values);
db.close();
}
//delete product from the database
public void deleteProduct(String productname)
{
SQLiteDatabase db= getWritableDatabase();
db.execSQL("DELETE FROM "+ TABLE_PRODUCTS + " WHERE " + COLUMN_PRODUCTNAME + " =\"" + productname + "\";" );
}
//printing out the database as a string
public String databaseToString()
{
String dbString ="";
SQLiteDatabase db= getWritableDatabase();
String query = "SELECT * FROM "+ TABLE_PRODUCTS + " WHERE 1";
//CURSOR POINTS TO A LOCATION IN THE DATABASE RESULTS
Cursor c= db.rawQuery(query,null);
//go to 1st row in your results
c.moveToFirst();
while(!c.isAfterLast())
{
if(c.getString(c.getColumnIndex("productname"))!=null)
{
dbString += c.getString(c.getColumnIndex("productname"));
dbString += "\n";
}
}
db.close();
return dbString;
}
}
我尝试将getwritabledatabase（）代码放在runnables中，但是他们可以为databasetostring（）方法执行此操作。
如何从Intent Service调用getWritableDatabase（）？
我想将此intent服务用于getWritableDatabase（）
import android.app.IntentService;
import android.content.Intent;
public class myintent extends IntentService{
public myintent(String name) {
super("myintent");
}
@Override
protected void onHandleIntent(Intent intent) {
}
}
我不知道如何通过INTENT SERVICE
来做到这一点这是应用启动后的logcat
8-19 17:56:08.848 15523-15523/? I/art﹕ Late-enabling -Xcheck:jni
08-19 17:56:08.848 15523-15523/? I/art﹕ VMHOOK: rlim_cur : 0 pid:15523
08-19 17:56:09.218 15523-15523/com.example.vashisht.sqliteapp D/Atlas﹕ Validating map...
08-19 17:56:09.278 15523-15554/com.example.vashisht.sqliteapp I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: TEST SBA LA.BF.1.1.1_RB1 AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.012 + c1105519 + c_apilogging ()
OpenGL ES Shader Compiler Version: E031.25.03.00
Build Date: 01/23/15 Fri
Local Branch:
Remote Branch: refs/tags/AU_LINUX_ANDROID_LA.BF.1.1.1_RB1.05.00.02.042.012
Local Patches: NONE
Reconstruct Branch: NOTHING
08-19 17:56:09.478 15523-15523/com.example.vashisht.sqliteapp I/InputMethodManager﹕ [startInputInner] EditorInfo { packageName=com.example.vashisht.sqliteapp, inputType=0x20001, imeOptions=0x40000006, privateImeOptions=null }, windowGainingFocus=android.view.ViewRootImpl$W@1287b4e7, mServedView=android.support.v7.widget.AppCompatEditText{e909894 VFED..CL .F....I. 90,222-990,335 #7f0c004f app:id/myinput}, mServedInputConnectionWrapper=android.view.inputmethod.InputMethodManager$ControlledInputConnectionWrapper@18863f3d
当我在文本字段中输入文本并点击添加按钮（向数据库表添加条目）时，应用程序冻结，logcat如下所示：
8-19 17:56:09.478 15523-15523/com.example.vashisht.sqliteapp I/InputMethodManager﹕ [startInputInner] EditorInfo { packageName=com.example.vashisht.sqliteapp, inputType=0x20001, imeOptions=0x40000006, privateImeOptions=null }, windowGainingFocus=android.view.ViewRootImpl$W@1287b4e7, mServedView=android.support.v7.widget.AppCompatEditText{e909894 VFED..CL .F....I. 90,222-990,335 #7f0c004f app:id/myinput}, mServedInputConnectionWrapper=android.view.inputmethod.InputMethodManager$ControlledInputConnectionWrapper@18863f3d
08-19 17:57:30.878 15523-15523/com.example.vashisht.sqliteapp I/InputMethodManager﹕ [startInputInner] EditorInfo { packageName=com.example.vashisht.sqliteapp, inputType=0x20001, imeOptions=0x40000006, privateImeOptions=null }, windowGainingFocus=null, mServedView=android.support.v7.widget.AppCompatEditText{e909894 VFED..CL .F...... 90,222-990,335 #7f0c004f app:id/myinput}, mServedInputConnectionWrapper=android.view.inputmethod.InputMethodManager$ControlledInputConnectionWrapper@2072768a
08-19 17:57:30.888 15523-15523/com.example.vashisht.sqliteapp W/IInputConnectionWrapper﹕ performPrivateCommand on inactive InputConnection
08-19 17:57:30.918 15523-15523/com.example.vashisht.sqliteapp W/IInputConnectionWrapper﹕ performPrivateCommand on inactive InputConnection
08-19 17:57:35.338 15523-15523/com.example.vashisht.sqliteapp I/InputMethodManager﹕ [startInputInner] EditorInfo { packageName=com.example.vashisht.sqliteapp, inputType=0x20001, imeOptions=0x40000006, privateImeOptions=null }, windowGainingFocus=android.view.ViewRootImpl$W@1287b4e7, mServedView=android.support.v7.widget.AppCompatEditText{e909894 VFED..CL .F....I. 90,222-990,335 #7f0c004f app:id/myinput}, mServedInputConnectionWrapper=android.view.inputmethod.InputMethodManager$ControlledInputConnectionWrapper@2996b4fb
08-19 17:57:42.158 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.091ms
08-19 17:57:42.608 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 9.910ms
08-19 17:57:55.408 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 180(6KB) AllocSpace objects, 108(15MB) LOS objects, 43% free, 5MB/9MB, paused 9.448ms total 36.167ms
08-19 17:57:59.468 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 43(1488B) AllocSpace objects, 24(4MB) LOS objects, 40% free, 6MB/10MB, paused 10.028ms total 18.813ms
08-19 17:58:00.478 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 9.383ms
08-19 17:58:11.218 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.913ms
08-19 17:58:14.328 15523-15537/com.example.vashisht.sqliteapp I/art﹕ WaitForGcToComplete blocked for 5.482ms for cause HeapTrim
08-19 17:58:15.628 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 60(2064B) AllocSpace objects, 32(7MB) LOS objects, 39% free, 6MB/10MB, paused 11.181ms total 21.280ms
08-19 17:58:16.248 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 10.318ms
08-19 17:58:26.088 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background sticky concurrent mark sweep GC freed 19(688B) AllocSpace objects, 9(2MB) LOS objects, 24% free, 5MB/7MB, paused 5.279ms total 10.035ms
08-19 17:58:28.778 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.467ms
08-19 17:58:31.278 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 6.368ms
08-19 17:58:34.298 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 6.308ms
08-19 17:58:34.348 15523-15537/com.example.vashisht.sqliteapp I/art﹕ WaitForGcToComplete blocked for 10.169ms for cause HeapTrim
08-19 17:58:36.798 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.915ms
08-19 17:58:38.918 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 16.815ms
08-19 17:58:44.538 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 8.032ms
08-19 17:58:44.878 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.364ms
08-19 17:58:44.878 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 35(1184B) AllocSpace objects, 22(7MB) LOS objects, 54% free, 3MB/7MB, paused 5.855ms total 17.791ms
08-19 17:58:46.248 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 7.053ms
08-19 17:58:46.268 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 9.842ms
08-19 17:58:46.268 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background sticky concurrent mark sweep GC freed 26(928B) AllocSpace objects, 12(4MB) LOS objects, 21% free, 6MB/7MB, paused 10.751ms total 18.381ms
08-19 17:58:48.828 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 5.178ms
08-19 17:58:48.868 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 7.268ms
08-19 17:58:49.538 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 9.654ms
08-19 17:58:50.838 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 7.434ms
08-19 17:58:54.758 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 8.813ms
08-19 17:58:54.758 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background sticky concurrent mark sweep GC freed 24(864B) AllocSpace objects, 11(3MB) LOS objects, 27% free, 6MB/8MB, paused 9.415ms total 14.852ms
08-19 17:58:56.798 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 9.198ms
08-19 17:58:56.808 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 39(1328B) AllocSpace objects, 23(8MB) LOS objects, 39% free, 6MB/10MB, paused 10.067ms total 19.829ms
08-19 17:59:03.098 15523-15538/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 7.042ms
08-19 17:59:03.108 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 23(784B) AllocSpace objects, 14(5MB) LOS objects, 54% free, 3MB/7MB, paused 7.720ms total 22.105ms
08-19 17:59:04.368 15523-15537/com.example.vashisht.sqliteapp I/art﹕ WaitForGcToComplete blocked for 8.374ms for cause HeapTrim
08-19 17:59:18.878 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 8.496ms
08-19 17:59:21.378 15523-15533/com.example.vashisht.sqliteapp W/art﹕ Suspending all threads took: 6.302ms
08-19 17:59:21.658 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 35(1184B) AllocSpace objects, 21(8MB) LOS objects, 39% free, 6MB/11MB, paused 5.077ms total 23.084ms
08-19 17:59:24.078 15523-15538/com.example.vashisht.sqliteapp I/art﹕ Background partial concurrent mark sweep GC freed 27(928B) AllocSpace objects, 15(6MB) LOS objects, 52% free, 3MB/7MB, paused 9.533ms total 23.103ms
然后我手动需要杀死应用程序，或者在一段时间后它说不响应!!
我修改了databasetostring（）方法以返回一个字符串数组，这样我就可以在listview中显示结果。
public String[] databaseToString()
{
String[] dbString;
dbString = new String[]{};
SQLiteDatabase db= getReadableDatabase();
String query = "SELECT * FROM "+ TABLE_PRODUCTS + " WHERE 1";
//CURSOR POINTS TO A LOCATION IN THE DATABASE RESULTS
Cursor c= db.rawQuery(query,null);
//go to 1st row in your results
c.moveToFirst();
int i=0;
while(!c.isAfterLast())
{
if(c.getString(c.getColumnIndex(COLUMN_PRODUCTNAME))!=null)
dbString[i] = c.getString(c.getColumnIndex(COLUMN_PRODUCTNAME));
i++;
}
db.close();
return dbString;
}
但是在这里，dbString[i] = c.getString(c.getColumnIndex(COLUMN_PRODUCTNAME));抛出数组超出范围异常???
答案 0 :(得分：1)
要从IntentService拨打电话，只需拨打此电话
sqLiteDatabase = getApplicationContext().getWritableDatabase();
自getApplicationContext()扩展IntentService
Context
答案 1 :(得分：-1)
}
db.close();
return dbString;
}
}
问题在这里，我忘了将光标移动到下一个结果，这导致无限循环！ oooops！
static FragmentB f;
public static FragmentB newInstance(String title) {
FragmentB f = new FragmentB();
Bundle b = new Bundle();
b.putString(ARG_STATION_TITLE, title);
f.setArguments(b);
return f;
}