如何使用 SQLite 表填充 ListView，其中 int 值与表中的列匹配

Question

我是 android 开发的新手，无法让它工作。我正在尝试使用从前一个列表视图传递的 int 值填充我的 AdminActivity 中的列表视图。然后需要使用该 int 值来使用与 users 表的 booking 列中的 int 值匹配的用户填充 ListView。

这是 DBHelper 类：

package com.example.shashank.fffffffffffffffffffffffffff;


import android.annotation.SuppressLint;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import androidx.annotation.Nullable;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class DBHelper extends SQLiteOpenHelper {
    public static final String DBNAME = "Login.db";
    public static final String FLIGHTS = "FLIGHTS";
    public static final String COLUMN_ID = "ID";
    public static final String COLUMN_DESTINATION = "DESTINATION";
    public static final String COLUMN_PRICE = "PRICE";
    public static final String COLUMN_DEPARTURE_TIME = "DEPARTURE_TIME";
    public static final String COLUMN_ARRIVAL_TIME = "ARRIVAL_TIME";
    public static final String COLUMN_DURATION = "DURATION";
    public static final String COLUMN_AVAILABLE_SEATS = "AVAILABLE_SEATS";
    public static final String USERS = "users";
    public static final String USERNAME = "username";
    public static final String PASSWORD = "password";
    public static final String EMAIL = "email";
    public static final String BALANCE = "balance";
    public static final String BOOKING = "booking";

    public DBHelper(Context context) {
        super(context, "Login.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase MyDB) {

        String createTable1 = ("create Table " + USERS + "(" + USERNAME + " TEXT primary key, " + PASSWORD + " TEXT, " + EMAIL + " TEXT UNIQUE, " + BALANCE + " REAL, " + BOOKING + " INTEGER)");
        MyDB.execSQL(createTable1);

        MyDB.execSQL("CREATE TABLE " + FLIGHTS + "(" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COLUMN_DESTINATION + " TEXT, " + COLUMN_PRICE + " REAL, " + COLUMN_DEPARTURE_TIME + " TEXT, " + COLUMN_ARRIVAL_TIME + " TEXT, " + COLUMN_DURATION + " TEXT, " + COLUMN_AVAILABLE_SEATS + " INTEGER)");


        ContentValues insertValues = new ContentValues();
        insertValues.put(COLUMN_DESTINATION, "Johannesburg");
        insertValues.put(COLUMN_PRICE, 1200);
        insertValues.put(COLUMN_DEPARTURE_TIME, "12:00");
        insertValues.put(COLUMN_ARRIVAL_TIME, "14:15");
        insertValues.put(COLUMN_DURATION, "2:15");
        insertValues.put(COLUMN_AVAILABLE_SEATS, 10);
        MyDB.insert(FLIGHTS, null, insertValues);

        ContentValues insertValues2 = new ContentValues();
        insertValues2.put(COLUMN_DESTINATION, "Johannesburg");
        insertValues2.put(COLUMN_PRICE, 1000);
        insertValues2.put(COLUMN_DEPARTURE_TIME, "16:00");
        insertValues2.put(COLUMN_ARRIVAL_TIME, "18:15");
        insertValues2.put(COLUMN_DURATION, "2:15");
        insertValues2.put(COLUMN_AVAILABLE_SEATS, 22);
        MyDB.insert(FLIGHTS, null, insertValues2);

        ContentValues insertValues3 = new ContentValues();
        insertValues3.put(COLUMN_DESTINATION, "Durban");
        insertValues3.put(COLUMN_PRICE, 800);
        insertValues3.put(COLUMN_DEPARTURE_TIME, "12:00");
        insertValues3.put(COLUMN_ARRIVAL_TIME, "14:00");
        insertValues3.put(COLUMN_DURATION, "2:00");
        insertValues3.put(COLUMN_AVAILABLE_SEATS, 2);
        MyDB.insert(FLIGHTS, null, insertValues3);

        ContentValues insertValues4 = new ContentValues();
        insertValues4.put(COLUMN_DESTINATION, "Port Elizabeth");
        insertValues4.put(COLUMN_PRICE, 700);
        insertValues4.put(COLUMN_DEPARTURE_TIME, "08:00");
        insertValues4.put(COLUMN_ARRIVAL_TIME, "09:10");
        insertValues4.put(COLUMN_DURATION, "1:10");
        insertValues4.put(COLUMN_AVAILABLE_SEATS, 0);
        MyDB.insert(FLIGHTS, null, insertValues4);

        ContentValues insertValues5 = new ContentValues();
        insertValues5.put(COLUMN_DESTINATION, "Port Elizabeth");
        insertValues5.put(COLUMN_PRICE, 700);
        insertValues5.put(COLUMN_DEPARTURE_TIME, "12:00");
        insertValues5.put(COLUMN_ARRIVAL_TIME, "13:10");
        insertValues5.put(COLUMN_DURATION, "1:10");
        insertValues5.put(COLUMN_AVAILABLE_SEATS, 22);
        MyDB.insert(FLIGHTS, null, insertValues5);

        ContentValues insertValues6 = new ContentValues();
        insertValues6.put(COLUMN_DESTINATION, "Durban");
        insertValues6.put(COLUMN_PRICE, 900);
        insertValues6.put(COLUMN_DEPARTURE_TIME, "14:00");
        insertValues6.put(COLUMN_ARRIVAL_TIME, "16:00");
        insertValues6.put(COLUMN_DURATION, "2:00");
        insertValues6.put(COLUMN_AVAILABLE_SEATS, 11);
        MyDB.insert(FLIGHTS, null, insertValues6);

        

    }


    @Override
    public void onUpgrade(SQLiteDatabase MyDB, int i, int i1) {
        MyDB.execSQL("drop Table if exists " + USERS);
        MyDB.execSQL("drop Table if exists " + FLIGHTS);

        onCreate(MyDB);
    }

    public Boolean insertData(String username, String password, String email, Double balance){
        SQLiteDatabase MyDB = this.getWritableDatabase();
        ContentValues contentValues= new ContentValues();
        contentValues.put(USERNAME, username);
        contentValues.put(PASSWORD, password);
        contentValues.put(EMAIL, email);
        contentValues.put(BALANCE, balance);
        long result = MyDB.insert(USERS, null, contentValues);
        if(result==-1) return false;
        else
            return true;
    }

    public Boolean checkusername(String username) {
        SQLiteDatabase MyDB = this.getWritableDatabase();
        Cursor cursor = MyDB.rawQuery("Select * from " + USERS + " where " + USERNAME + " = ?", new String[]{username});
        if (cursor.getCount() > 0)
            return true;
        else
            return false;
    }

    public Boolean checkusernamepassword(String username, String password){
        SQLiteDatabase MyDB = this.getWritableDatabase();
        Cursor cursor = MyDB.rawQuery("Select * from " + USERS + " where " + USERNAME + " = ? and " + PASSWORD + " = ?", new String[] {username,password});
        if(cursor.getCount()>0)
            return true;
        else
            return false;
    }


    public List<FlightsModel> getEveryone(){

        List<FlightsModel> returnList = new ArrayList<>();

        String queryString = "SELECT * FROM " + FLIGHTS;

        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.rawQuery(queryString, null);

        if(cursor.moveToFirst()){
            do {
                int id = cursor.getInt(0);
                String destination = cursor.getString(1);
                double price = cursor.getDouble(2);
                String departure = cursor.getString(3);
                String arrival = cursor.getString(4);
                String duration = cursor.getString(5);
                int space = cursor.getInt(6);

                FlightsModel newFlight = new FlightsModel(id, destination, price, departure, arrival, duration, space);
                returnList.add(newFlight);


            }while (cursor.moveToNext());
        }
        else{

        }
        cursor.close();
        db.close();
        return returnList;
    }



    @SuppressLint("Range") // suppress Bug/issue with getColumnIndex
    public FlightsModel getFlightById(int id) {
        FlightsModel rv;
        SQLiteDatabase db = this.getWritableDatabase();
        // Uses the query convenience method rather than raw query
        Cursor csr = db.query(FLIGHTS,null,COLUMN_ID+"=?",new String[]{String.valueOf(id)},null,null,null);
        if (csr.moveToFirst()) {
            rv = new FlightsModel(
                    csr.getInt(csr.getColumnIndex(COLUMN_ID)),
                    csr.getString(csr.getColumnIndex(COLUMN_DESTINATION)),
                    csr.getDouble(csr.getColumnIndex(COLUMN_PRICE)),
                    csr.getString(csr.getColumnIndex(COLUMN_DEPARTURE_TIME)),
                    csr.getString(csr.getColumnIndex(COLUMN_ARRIVAL_TIME)),
                    csr.getString(csr.getColumnIndex(COLUMN_DURATION)),
                    csr.getInt(csr.getColumnIndex(COLUMN_AVAILABLE_SEATS))
            );
        }  else {
            rv = new FlightsModel();
        }
        csr.close();
        // No need to close the database (inefficient to keep opening and closing db)
        return rv;
    }



    @SuppressLint("Range")
    public UsersModel getPasswordByName(String name){

        UsersModel rv;
        SQLiteDatabase db = this.getWritableDatabase();

        Cursor cr = db.query(USERS, null, USERNAME+"=?", new String[]{name}, null, null, null);

        if (cr.moveToFirst()) {
            rv = new UsersModel(
                    cr.getString(cr.getColumnIndex(USERNAME)),
                    cr.getString(cr.getColumnIndex(PASSWORD)),
                    cr.getString(cr.getColumnIndex(EMAIL)),
                    cr.getDouble(cr.getColumnIndex(BALANCE)),
                    cr.getInt(cr.getColumnIndex(BOOKING))

            );
        }  else rv = new UsersModel();

        cr.close();
        return rv;
    }

    public int setBookingByUserName(int bookingAmount, String userName) {
        ContentValues cv = new ContentValues();
        cv.put(BOOKING,bookingAmount);
        return this.getWritableDatabase().update(USERS,cv,USERNAME+"=?",new String[]{userName});
    }

    public double makingPayment(double balance, String userName){
        ContentValues cv = new ContentValues();
        cv.put(BALANCE,balance);
        return this.getWritableDatabase().update(USERS,cv,USERNAME+"=?",new String[]{userName});
    }


    public int setAvailableSeatsAfterPayment(int seats, int flightID){
        ContentValues cv = new ContentValues();
        cv.put(COLUMN_AVAILABLE_SEATS,seats);
        return this.getWritableDatabase().update(FLIGHTS,cv,COLUMN_ID+"=?",new String[]{String.valueOf(flightID)});
    }


    public int cancelBooking(int bookingAmount, String userName){
        ContentValues cv = new ContentValues();
        cv.put(BOOKING,bookingAmount);
        return this.getWritableDatabase().update(USERS,cv,USERNAME+"=?",new String[]{String.valueOf(userName)});
    }


    @SuppressLint("Range")
    public UsersModel getUsersModelByName(String userName) {
        UsersModel rv = new UsersModel();
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor csr = db.query(USERS,null,USERNAME+"=?", new String[]{userName},null,null,null);
        if (csr.moveToFirst()) {
            rv = new UsersModel(
                    csr.getString(csr.getColumnIndex(USERNAME)),
                    csr.getString(csr.getColumnIndex(PASSWORD)),
                    csr.getString(csr.getColumnIndex(EMAIL)),
                    csr.getDouble(csr.getColumnIndex(BALANCE)),
                    csr.getInt(csr.getColumnIndex(BOOKING))
            );
        }
        csr.close();
        return rv;
    }

    public boolean makeBooking(String userName, int bookingId) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();
        cv.put(BOOKING,bookingId);
        return db.update(USERS,cv,USERNAME + "=?", new String[]{userName}) > 0;
    }


    public String makeBookReceiptFile(String userName, Context context) {
        String rcpts_directory = "receipts";
        String rv = "";
        SQLiteDatabase db = this.getWritableDatabase();
        UsersModel currentUser = getUsersModelByName(userName);
        FlightsModel currentFlightsModel = new FlightsModel();
        if (currentUser.booking > 0) {
            currentFlightsModel = getFlightById(currentUser.booking);
            if (currentFlightsModel.getId() < 1) {
                rv = "INVALID - unable to extract booking for id " + currentUser.booking;
            }
        } else {
            rv = "INVALID - unable to extract user who's name is " + userName;
        }
        if (rv.length() > 0) return rv;
        String rcpt_filename =
                currentUser.getName() + "-" +
                        currentFlightsModel.getDestination() + "-" +
                        currentFlightsModel.getDeparture_time() + "-" +
                        currentFlightsModel.getArrival_time()
                ;
        File rcpt = new File(context.getFilesDir().getPath() + File.separatorChar + rcpts_directory + File.separatorChar + rcpt_filename);
        rcpt.getParentFile().mkdirs();
        try {
            FileWriter fw = new FileWriter(rcpt);
            fw.write("Invoice for flight:" + "\n" +
                    "\n" + "-----------------------------------------------" +
                    "\n" + "User: " + userName +
                    "\n" + "Destination: " + currentFlightsModel.getDestination()+
                    "\n" + "Departure time at: " + currentFlightsModel.getDeparture_time() +
                    "\n" + "Arrival time at: " + currentFlightsModel.getArrival_time() +
                    "\n" + "Duration of flight: " + currentFlightsModel.getDuration() +
                    "\n" + "Amount paid: " + "R" + currentFlightsModel.getPrice()
            );
            fw.flush();
            fw.close();
            rv = rcpt.getAbsolutePath();
        } catch (IOException e) {
            e.printStackTrace();
            rv = "IOERROR - " + e.getMessage();
        }
        return rv;
    }


}

这是用户模型类：

package com.example.shashank.fffffffffffffffffffffffffff;

public class UsersModel {

    private String name, password, email;

    private double balance;

    int booking;

    public UsersModel(String name, String password, String email, double balance, int booking) {
        this.name = name;
        this.password = password;
        this.email = email;
        this.balance = balance;
        this.booking = booking;
    }

    public UsersModel() {

    }

    public int getBooking() {
        return booking;
    }

    public void setBooking(int booking) {
        this.booking = booking;
    }

    public double getBalance() {
        return balance;
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "UsersModel{" +
                "name='" + name + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

这里是 AdminActivity：

package com.example.shashank.fffffffffffffffffffffffffff;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.Toast;

public class AdminActivity extends AppCompatActivity {

    ListView userList;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_admin);

        userList = findViewById(R.id.userList);

        int intValue;
        Intent mIntent = getIntent();
        intValue = mIntent.getIntExtra("intVariableName", 0);
        intValue = intValue + 1;

        Toast.makeText(AdminActivity.this, Integer.toString(intValue), Toast.LENGTH_SHORT).show();


    }
}

我想使用 intValue 并用 intValue 与他们的预订列中的 int 值匹配的所有用户填充列表。 任何帮助将不胜感激，谢谢

Answer 1

首先在DBHelper中添加一个方法，通过int(BOOKING)获取用户列表作为Cursor比如:-

public Cursor getUsersByBookingNumber(int bookingNumber) {
    SQLiteDatabase MyDB = this.getWritableDatabase();
    /* return cursor with ALL columns AND a column called _ID which has the rowid */
    return MyDB.query(USERS, new String[]{"*","rowid AS " + BaseColumns._ID},BOOKING+"=?",new String[]{String.valueOf(bookingNumber)},null,null,null);
}

• 请注意，游标适配器必须有一个列名 _id（BaseColumns._ID 解析为 _id），因此这是通过获取 rowid 列 AS _id 来实现的。

ListView 需要一个适配器，Cursor Adapters 是为与 Cursors 一起使用而设计的，所以使用 SimpleCursorAdapter。

适配器需要一个用于显示列表中每个项目的布局（一个项目可以由多个视图组成）。在这种情况下，将使用库存布局simple_list_item2（您可能想要创建自己的布局）。您设置适配器，然后告诉 ListView 使用什么适配器。

以上所有内容都在各自的活动中完成。为了证明 MainActivity 已被使用，它是：-

public class MainActivity extends AppCompatActivity {

    DBHelper dbHelper;
    Cursor userListViewCursor; /* The Cursor to be used for the ListView */
    SimpleCursorAdapter sca; /* The adapter for the ListView */
    ListView userListView; /* The ListView */
    int currentBookingNumber; /* the int */

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        userListView = this.findViewById(R.id.activity_admin);
        /* Prepare Database */
        dbHelper = new DBHelper(this);
        /* Add some test data */
        dbHelper.insertData("Fred","password","fred@email",0.00);
        dbHelper.insertData("Mary","password","mary@email",0.00);
        dbHelper.insertData("Jane","password","jane@email",0.00);
        dbHelper.insertData("Tom","password","tom@email",0.00);
        dbHelper.insertData("Sue","password","sue@email",0.00);
        dbHelper.insertData("Bob","password","bob@email",0.00);

        dbHelper.makeBooking("Fred",1);
        dbHelper.makeBooking("Mary",2);
        dbHelper.makeBooking("Sue",3);
        dbHelper.makeBooking("Jane",1);
        dbHelper.makeBooking("Tom",2);
        dbHelper.makeBooking("Bob",1);

        currentBookingNumber = 1; /*(mimic getting the booking number)*/
        /* setup the ListView as the adapter will be null */
        setupOrRefreshLIstView(currentBookingNumber);

    }

    private void setupOrRefreshLIstView(int bookingNumber) {
        userListViewCursor = dbHelper.getUsersByBookingNumber(bookingNumber);
        if (sca == null) {
            sca = new SimpleCursorAdapter(
                    this,
                    /* The layout for each item in the ListView */
                    android.R.layout.simple_list_item_2,
                    userListViewCursor,
                    /* Columns in the Cursors */
                    new String[]{DBHelper.USERNAME,DBHelper.EMAIL},
                    /* id of the View in the ListView's item layout  that corresponds with the column in the Cursor*/
                    /* NOTE 1st column corresponds to first id and so on so :- */
                    /* USERNAME column value is placed into text1 View, EMAIl column into text2 */
                    /* simple list item has 2 TextViews with ids text1 and text2 */
                    new int[]{android.R.id.text1,android.R.id.text2},
                    0
            );
            /* Tie the adapter sca to the ListView userListView */
            userListView.setAdapter(sca);
            /* set listeners here if required e.g. */
            userListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @SuppressLint("Range")
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int i, long l /* will be the value of _id column */) {
                    Toast.makeText(view.getContext(),
                            "You clicked on the row with _id " + l
                                    + " the user is " + userListViewCursor.getString(userListViewCursor.getColumnIndex(DBHelper.USERNAME))
                                    + " the email is " + userListViewCursor.getString(userListViewCursor.getColumnIndex(DBHelper.EMAIL))
                                    /* even though balance etc is not shown as the values are in the cursor they can be retrieved */
                                    + " the balance is " + userListViewCursor.getDouble(userListViewCursor.getColumnIndex(DBHelper.BALANCE))
                            ,
                            Toast.LENGTH_SHORT).show();
                }
            });
        } else {
            sca.swapCursor(userListViewCursor);
        }
    }

    /* if the activity is resumed then refresh the ListView just in case the data has changed */
    @Override
    protected void onResume() {
        super.onResume();
        setupOrRefreshLIstView(currentBookingNumber);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        userListViewCursor.close(); /*should always close a cursor when done with it */

    }
}

• 请注意，生成并加载了一些测试数据以进行演示。
• 已添加onItemClickListener，这将显示所点击项目的详细信息。

运行上述结果：-