如何获取值listview项并使用它在where子句的数据库中插入数据

Question

我有一个listview，显示从sqlitedatabase检索的studentdata。当您点击某个项目时，您将进入可以为学生评分的活动。现在，我想知道在单击“保存”按钮时如何插入该等级。必须将成绩插入到正确的学生中（此学生之前已在上一个活动的列表视图中选择）。这是我的DBAdapter：

package com.ipmedt4.challengeweek_v2;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

/**
* Created by Charlie on 28-12-2014.
 */
public class StudentDBAdapter {
public static final String KEY_ROWID = "_id";
public static final String KEY_NAAM = "_naam";
public static final String KEY_STUDENTNUMMER = "_studentnummer";
public static final String KEY_KLAS = "_klas";
public static final String KEY_CIJFER = "_cijfer";
public static final String KEY_OPMERKINGEN = "_opmerkingen";

private static  final String TAG = "StudentDBAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDB;

private static final String DATABASE_NAME = "Challengeweek";
private static final String SQLITE_TABLE = "Studenten";
private static final int DATABASE_VERSION = 1;

private final Context mCtx;

private static final String DATABASE_CREATE = " CREATE TABLE IF NOT EXISTS " + SQLITE_TABLE + "("    +
        KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_NAAM + "," + KEY_STUDENTNUMMER + ","
        + KEY_KLAS + "," + KEY_CIJFER + "," + KEY_OPMERKINGEN +  ")";

private static class DatabaseHelper extends SQLiteOpenHelper {

    DatabaseHelper(Context context){
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db){
        Log.w(TAG, DATABASE_CREATE);
        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" + SQLITE_TABLE);
        onCreate(db);
    }
}

public StudentDBAdapter (Context ctx){
    this.mCtx = ctx;
 }
 public StudentDBAdapter open () throws SQLiteException{
    mDbHelper = new DatabaseHelper(mCtx);
    mDB = mDbHelper.getWritableDatabase();
    return this;
}

public void close() {
    if (mDbHelper != null) {
        mDbHelper.close();
    }
}
public long createStudent (String naam, String studentnummer, String klas){
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_NAAM, naam);
    initialValues.put(KEY_STUDENTNUMMER, studentnummer);
    initialValues.put(KEY_KLAS, klas);

    return mDB.insert(SQLITE_TABLE, null, initialValues);
}


public boolean deleteAllStudenten(){
    int doneDelete = 0;
    doneDelete = mDB.delete(SQLITE_TABLE, null, null);
    Log.w(TAG, Integer.toString(doneDelete));
    return doneDelete > 0;

}


public Cursor fetchStudentenbyName(String inputText) throws SQLiteException{
Log.w(TAG, inputText);
Cursor mCursor = null;
    if (inputText == null || inputText.length() == 0){
        mCursor = mDB.query(SQLITE_TABLE, new String[] {
                KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS
        }, null, null, null, null, null);
    }
    else {
        mCursor = mDB.query(true, SQLITE_TABLE, new String [] {KEY_ROWID,
        KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS}, KEY_NAAM + "like '%" + inputText +
        "%'", null, null, null, null, null);
    }
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}

  public Cursor showAlleStudenten(){
   Cursor mCursor = mDB.query(SQLITE_TABLE, new String[] {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER,
   KEY_KLAS}, null, null, null, null, null);

   if (mCursor != null){
       mCursor.moveToFirst();
   }
   return mCursor;}

public Cursor SelecteerStudenten1A(){
    String Table = "Studenten";
    String [] fields = {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS};
    String where = "_klas = 'INF1A'";
    Cursor mCursor = mDB.query(Table, fields, where, null, null, null, null);

    if(mCursor !=null){
        mCursor.moveToFirst();
    }
    return mCursor;
}



public Cursor SelecteerStudenten1B(){
    String Table = "Studenten";
    String [] fields = {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS};
    String where = "_klas = 'INF1B'";
    Cursor mCursor = mDB.query(Table, fields, where, null, null, null, null);
    if(mCursor !=null){
        mCursor.moveToFirst();
    }
    return mCursor;
}

public Cursor SelecteerStudenten1C(){
    String Table = "Studenten";
    String [] fields = {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS};
    String where = "_klas = 'INF1C'";
    Cursor mCursor = mDB.query(Table, fields, where, null, null, null, null);
    if(mCursor !=null){
        mCursor.moveToFirst();
    }
    return mCursor;
}

public Cursor SelecteerStudenten1D(){
    String Table = "Studenten";
    String [] fields = {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS};
    String where = "_klas = 'INF1D'";
    Cursor mCursor = mDB.query(Table, fields, where, null, null, null, null);
    if(mCursor !=null){
        mCursor.moveToFirst();
    }
    return mCursor;
}

public Cursor SelecteerStudenten1E(){
    String Table = "Studenten";
    String [] fields = {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS};
    String where = "_klas = 'INF1E'";
    Cursor mCursor = mDB.query(Table, fields, where, null, null, null, null);
    if(mCursor !=null){
        mCursor.moveToFirst();
    }
    return mCursor;
}

public Cursor SelecteerStudenten1F(){
    String Table = "Studenten";
    String [] fields = {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS};
    String where = "_klas = 'INF1F'";
    Cursor mCursor = mDB.query(Table, fields, where, null, null, null, null);
    if(mCursor !=null){
        mCursor.moveToFirst();
    }
    return mCursor;
}

public Cursor SelecteerStudenten1G(){
    String Table = "Studenten";
    String [] fields = {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS};
    String where = "_klas = 'INF1G'";
    Cursor mCursor = mDB.query(Table, fields, where, null, null, null, null);
    if(mCursor !=null){
        mCursor.moveToFirst();
    }
    return mCursor;
}

public Cursor SelecteerStudenten1H(){
    String Table = "Studenten";
    String [] fields = {KEY_ROWID, KEY_NAAM, KEY_STUDENTNUMMER, KEY_KLAS};
    String where = "_klas = 'INF1H'";
    Cursor mCursor = mDB.query(Table, fields, where, null, null, null, null);
    if(mCursor !=null){
        mCursor.moveToFirst();
    }
    return mCursor;
}

public void insertStudenten(){
    createStudent("Adel, Pieter", "s1078455", "INF1G");
    createStudent("Bieber, Justin", "s1084567", "INF1D");
    createStudent("Dadel, Maria", "s1087499", "INF1F");
    createStudent("Dekker, Vera", "s1084235", "INF1B");
    createStudent("Elegast, Karel", "s1074211", "INF1E");
    createStudent("Emmer, Lisa", "s1074326", "INF1C");
    createStudent("Hendriksen, Dorien", "s1074788", "INF1A");
    createStudent("Krokus, Joke", "s1089413", "INF1H");
    createStudent("Mandarijn, Max", "s1084211", "INF1H");
    createStudent("Nelissen, Henk", "s1087465", "INF1F");
    createStudent("Rokers, Lianne", "s1071244", "INF1G");
    createStudent("Tekkel, Hester ", "s1071586", "INF1C");
    createStudent("Uitjes, Berend ", "s1087451", "INF1A");
    createStudent("Venkeltje, Sophia ", "s1075612", "INF1B");
    createStudent("Vlieger, Olaf ", "s1074127", "INF1E");
    createStudent("Vogel, Bas ", "s1084522", "INF1A");
    createStudent("Water, Michiel ", "s1084531", "INF1H");
    createStudent("Weken, Dirk ", "s1074537", "INF1D");
    createStudent("Wieken, Stefanie ", "s1084511", "INF1C");
    createStudent("Zeker, Donald ", "s1077369", "INF1E");


}
} 

这是我的ListView课程，概述了所有学生：

package com.ipmedt4.challengeweek_v2;

import android.annotation.TargetApi;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Build;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.FilterQueryProvider;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;


public class OverzichtStudenten extends ActionBarActivity {
private StudentDBAdapter dbHelper;
private SimpleCursorAdapter dataAdapter;
ListView listview;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_overzicht_studenten);
    dbHelper = new StudentDBAdapter(this);
    dbHelper.open();

    //maak alle data schoon
    dbHelper.deleteAllStudenten();

    //toevoegen van data
    dbHelper.insertStudenten();

    //genereren ListView van SQLiteDatabase
    displayListView();

}


@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private void displayListView(){
    Cursor cursor = dbHelper.showAlleStudenten();

    //selecteer gewenste kolommen
    String[] columns = new String[]{
            StudentDBAdapter.KEY_NAAM,
            StudentDBAdapter.KEY_STUDENTNUMMER,
            StudentDBAdapter.KEY_KLAS
    };

    //In XML gedefiniërde Views
    int[] to = new int[]{
      R.id.naam,
      R.id.studentnummer,
      R.id.klas
    };


    dataAdapter = new SimpleCursorAdapter(
            this, R.layout.student_info,
            cursor,
            columns,
            to,
            1);

    ListView listView = (ListView) findViewById(R.id.listView1);
    listView.setAdapter(dataAdapter);

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> listView, View view, int position, long id) {
        Cursor cursor = (Cursor) listView.getItemAtPosition(position);
            Intent myintent2 = new Intent(view.getContext(), Beoordelingscherm.class);
            startActivity(myintent2);



        }
    });

    EditText myFilter = (EditText) findViewById(R.id.myFilter);
    myFilter.addTextChangedListener(new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            { dataAdapter.getFilter().filter(s.toString());
        }}

        @Override
        public void afterTextChanged(Editable s) {

        }
    });
    dataAdapter.setFilterQueryProvider(new FilterQueryProvider() {
        @Override
        public Cursor runQuery(CharSequence constraint) {
            return dbHelper.fetchStudentenbyName(constraint.toString());
        }
    });
}






@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_overzicht_studenten, 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);
}
}

所以，有一个listview活动，它是学生的概述（有学生姓名，班级和学生编号）。当您点击学生时，您将进入一项活动，您可以在该活动中为学生评分并将该成绩保存在数据库中。 我知道我必须在DBAdapter类中创建一个方法，我可以在您可以为学生评分的活动中实现该方法。我想到了Contentvalues.get。 我的问题是：如何检索listview中项目的值，以便我可以使用这些值在数据库中的正确学生中插入成绩（在下一个活动中）？所以我可以使用这些值来进行SQL查询？我还有一个课程“学生”，其中包含吸气剂和制定者。谢谢！

Answer 1

修改onItemClick，使用Intent.putExtra("key_name",value)将所选行的位置或ID传递给下一个活动。然后，您可以使用getIntent.getIntExtra("key_name")

在后续活动中检索它