如何通过数据库中的信息过滤listView

我已经编写了一个应用程序，可以在数据库中保存主题和标记。我必须解决的最后一个问题是，我如何从Marks类中筛选ListView，以便它只显示相应的主题。如何通过数据库中的信息过滤listView

该应用程序由三个类组成。

主营：

package maturaarbeit.nicola_pfister.marks; 

import maturaarbeit.nicola_pfister.marks.database.DBAdapter; 
import android.app.AlertDialog.Builder; 
import android.app.ListActivity; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.database.Cursor; 
import android.os.Bundle; 
import android.support.v4.widget.SimpleCursorAdapter; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemClickListener; 
import android.widget.EditText; 
import android.widget.ListView; 

public class Main extends ListActivity { 

    DBAdapter db = new DBAdapter(this); 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.subjects); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     db.close(); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     db.open(); 
     getData(); 
    } 

    @SuppressWarnings("deprecation") 
    private void getData() { 
     SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, 
       android.R.layout.simple_list_item_1, 
       db.getAllSubjects(), 
       new String[] { "subject" }, 
       new int[] { android.R.id.text1 }); 

     ListView listView = (ListView) findViewById(android.R.id.list); 
     listView.setAdapter(adapter); 
     listView.setOnItemClickListener(new OnItemClickListener() { 

      @Override 
      public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long id) { 

      Cursor cursor = db.getSubject(id); 
      String subject = null; 
      try { 
       subject = cursor.getString(cursor.getColumnIndex("subject")); 
      } catch (Exception e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
      Intent intent = new Intent(Main.this, Marks.class); 
      intent.putExtra("selected", subject); 
      startActivity(intent); 
      } 
     }); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.subjects, menu); 
     return true; 
    } 

    public boolean onOptionsItemSelected(MenuItem item) { 
     switch (item.getItemId()) { 
     case R.id.menu_add: 
      Builder builder = new Builder(this); 
      final EditText input = new EditText(this); 
      builder 
       .setTitle(R.string.dialog_addsubject) 
       .setView(input) 
       .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() { 

        public void onClick(DialogInterface dialog, int which) { 
         String value = input.getText().toString(); 
         db.insertSubject(value); 
         getData(); 
        } 
       }) 
       .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() { 

        public void onClick(DialogInterface dialog, int which) { 
        } 

       }) 
       .show(); 
      break; 
     case R.id.menu_delete: 
//   getData(); 
      break; 
     } 
     return super.onOptionsItemSelected(item); 
    } 
}

商标：

package maturaarbeit.nicola_pfister.marks; 

import java.util.Calendar; 

import maturaarbeit.nicola_pfister.marks.database.DBAdapter; 
import android.app.AlertDialog.Builder; 
import android.app.ListActivity; 
import android.content.DialogInterface; 
import android.os.Bundle; 
import android.support.v4.widget.SimpleCursorAdapter; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 
import android.widget.EditText; 
import android.widget.ListView; 


public class Marks extends ListActivity { 

    DBAdapter db = new DBAdapter(this); 


    String selection = null; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.marks); 

     final Bundle extras = getIntent().getExtras(); 
     selection = extras.getString("selected"); 

     if (extras!= null) { 
      setTitle(selection); 
     } 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     db.close(); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     db.open(); 
     getData(); 

    } 

    @SuppressWarnings("deprecation") 
    private void getData() { 
     SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, 
       android.R.layout.simple_list_item_1, 
       db.getAllMarks(), 
       new String[] { "value" }, 
       new int[] { android.R.id.text1 }); 


     ListView listView = (ListView) findViewById(android.R.id.list); 
     listView.setAdapter(adapter); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     MenuInflater inflater = getMenuInflater(); 
     inflater.inflate(R.menu.marks, menu); 
     return true; 
    } 

    public boolean onOptionsItemSelected(MenuItem item) { 
     switch (item.getItemId()) { 
     case R.id.menu_add: 
      Builder builder = new Builder(this); 
      final EditText input = new EditText(this); 
      builder 
       .setTitle(R.string.dialog_addmark) 
       .setView(input) 
       .setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() { 

        public void onClick(DialogInterface dialog, int which) { 
         String value = input.getText().toString(); 

         Calendar cal = Calendar.getInstance(); 
         int day = cal.get(Calendar.DAY_OF_MONTH); 
         int month = cal.get(Calendar.MONTH) + 1; 
         final String date = day + "." + month + "."; 

         db.insertMark(date, selection, value); 
         getData(); 
        } 
       }) 
       .setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() { 

        public void onClick(DialogInterface dialog, int which) { 
        } 

       }) 
       .show(); 
      break; 
     case R.id.menu_delete: 
      break; 
     } 
     return super.onOptionsItemSelected(item); 
    } 
}

而且将对DBAdapter：

package maturaarbeit.nicola_pfister.marks.database; 

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; 

public class DBAdapter { 

    int id = 0; 
    public static final String KEY_ROWID = "_id"; 
    public static final String KEY_DATE = "date"; 
    public static final String KEY_SUBJECT = "subject"; 
    public static final String KEY_VALUE = "value"; 
    public static final String TAG = "DBAdapter"; 

    private static final String DATABASE_NAME = "database"; 
    private static final String DATABASE_TABLE_MARKS = "marks"; 
    private static final String DATABASE_TABLE_SUBJECTS = "subjects"; 
    private static final int DATABASE_VERSION = 1; 

    private static final String DATABASE_CREATE_MARKS = 
      "create table " + DATABASE_TABLE_MARKS + " (" + KEY_ROWID + " integer primary key autoincrement, " + 
        KEY_DATE +" text not null, " + 
        KEY_SUBJECT +" text not null, " + 
        KEY_VALUE +" text not null" + ");"; 

    private static final String DATABASE_CREATE_SUBJECTS = 
      "create table " + DATABASE_TABLE_SUBJECTS + " (" + KEY_ROWID + " integer primary key autoincrement, " + 
        KEY_SUBJECT +" text not null " + ");"; 

    @SuppressWarnings("unused") 
    private final Context context; 

    private DatabaseHelper DBHelper; 
    private SQLiteDatabase db; 

    public DBAdapter(Context context) { 
     this.context = context; 
     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_MARKS); 
      db.execSQL(DATABASE_CREATE_SUBJECTS); 
     } 

     @Override 
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
      db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE_MARKS); 
      db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE_SUBJECTS); 
      onCreate(db); 
     } 
    } 

    public DBAdapter open() throws SQLException { 
     db = DBHelper.getWritableDatabase(); 
     return this; 
    } 

    public void close() { 
     DBHelper.close(); 
    } 

    public long insertMark (String date, String subject, String value) { 
     ContentValues initialValues = new ContentValues(); 
     initialValues.put(KEY_DATE, date); 
     initialValues.put(KEY_SUBJECT, subject); 
     initialValues.put(KEY_VALUE, value); 
     return db.insert(DATABASE_TABLE_MARKS, null, initialValues); 
    } 

    public boolean deleteMark(long rowId) { 
     return db.delete(DATABASE_TABLE_MARKS, KEY_ROWID + "=" + rowId, null) > 0; 
    } 

    public Cursor getAllMarks() { 
     return db.query(DATABASE_TABLE_MARKS, new String[] { 
       KEY_ROWID, 
       KEY_DATE, 
       KEY_SUBJECT, 
       KEY_VALUE 
     }, null, null, null, null, null); 
    } 

    public Cursor getMark(long rowId) throws SQLException { 
     Cursor mCursor = 
       db.query(true, DATABASE_TABLE_MARKS, new String[] { 
         KEY_ROWID, 
         KEY_DATE, 
         KEY_SUBJECT, 
         KEY_VALUE 
       }, 
       KEY_ROWID + "=" + rowId, 
       null, null, null, null, null); 
     if (mCursor != null) { 
      mCursor.moveToFirst(); 
     } 
     return mCursor; 
    } 

    public boolean updateMark(long rowId, String date, String subject, String value) { 
     ContentValues args = new ContentValues(); 
     args.put(KEY_DATE, date); 
     args.put(KEY_SUBJECT, subject); 
     args.put(KEY_VALUE, value); 
     return db.update(DATABASE_TABLE_MARKS, args, KEY_ROWID + "=" + rowId, null) >0; 
    } 

    public void deleteMark() { 
     db.delete(DATABASE_TABLE_MARKS, null, null); 
    } 

    public long insertSubject (String subject) { 
     ContentValues initialValues = new ContentValues(); 
     initialValues.put(KEY_SUBJECT, subject); 
     return db.insert(DATABASE_TABLE_SUBJECTS, null, initialValues); 
    } 

    public boolean updateSubject(long rowId, String subject) { 
     ContentValues args = new ContentValues(); 
     args.put(KEY_SUBJECT, subject); 
     return db.update(DATABASE_TABLE_MARKS, args, KEY_ROWID + "=" + rowId, null) >0; 
    } 

    public Cursor getSubject(long rowId) throws SQLException { 
     Cursor mCursor = 
       db.query(true, DATABASE_TABLE_SUBJECTS, new String[] { 
         KEY_ROWID, 
         KEY_SUBJECT 
       }, 
       KEY_ROWID + "=" + rowId, 
       null, null, null, null, null); 
     if (mCursor != null) { 
      mCursor.moveToFirst(); 
     } 
     return mCursor; 
    } 

    public Cursor getAllSubjects() { 
     return db.query(DATABASE_TABLE_SUBJECTS, new String[] { 
       KEY_ROWID, 
       KEY_SUBJECT 
     }, null, null, null, null, null); 
    } 
}

像现在，标记的活动表明即使任何主题的所有商标标题说了别的。我想使用我的数据库的“主题”列过滤ListView，以便只显示数据库的项目，这些项目与标题所述的主题相同。即时通讯开始通过各种不同的解决方案，我发现在互联网上获得不知所措，我不能对任何人适应了我的问题......

预先感谢您

来源

2012-10-15 BlueHazard

也许创建这样的方法在你的DBAdapter中，并在你的SimpleCursorAdapter中使用它来代替db.getAllMarks（），传入选择。

public Cursor getMarks(String subject) { 
    return db.query(DATABASE_TABLE_MARKS, new String[] { 
      KEY_ROWID, 
      KEY_DATE, 
      KEY_SUBJECT, 
      KEY_VALUE 
    }, KEY_SUBJECT + " = ?", subject, null, null, null); 
}

来源

2012-10-15 21:53:47 mfelix

这不是整个解决方案，但肯定帮助我解决了我的问题。谢谢！ – BlueHazard

如何通过数据库中的信息过滤listView

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