java - 如何更新 ListView 中的记录以及android中的数据库

Question

我希望当我单击列表项时，在 SQL 中保存的所有编辑文本内容都显示在编辑账单 Activity 中，但我只能检索名称并在 Intent 中再次显示。如果我在 editbills_activity 中再次保存现有记录，它应该使用新数据更新记录，而不是保存其他数据。这是我的 DBAdapter.java

package com.example.dhruv.bills;
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;
import android.util.Log; 
public class DBAdapter {
public static final String KEY_ROWID = "id";
public static final String KEY_NAME = "name";
public static final String KEY_AMOUNT = "amount";
public static final String KEY_DUEDATE = "duedate";
private static final String TAG = "DBAdapter";

private static final String DATABASE_NAME = "billsdb";
private static final String DATABASE_TABLE = "bills";
private static final int DATABASE_VERSION = 2;



private static final String DATABASE_CREATE =
        "create table if not exists assignments (id integer primary key autoincrement, "
                + "name VARCHAR not null, amount VARCHAR, duedate date );";

// Replaces DATABASE_CREATE using the one source definition
private static final String TABLE_CREATE =
        "CREATE TABLE IF NOT EXISTS " + DATABASE_TABLE + "(" +
                KEY_ROWID + " INTEGER PRIMARY KEY, " + // AUTOINCREMENT NOT REQD
                KEY_NAME + " DATE NOT NULL, " +
                KEY_AMOUNT + " VARCHAR ," +
                KEY_DUEDATE + " DATE " +
                ")";

private final Context context;

private DatabaseHelper DBHelper;
private SQLiteDatabase db;

public DBAdapter(Context ctx)
{
    this.context = ctx;
    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(TABLE_CREATE); // NO need to encapsulate in try clause
    }

    @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 contacts"); //????????
        db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
        onCreate(db);
    }
}

//---opens the database---
public DBAdapter open() throws SQLException
{
    db = DBHelper.getWritableDatabase();
    return this;
}

//---closes the database---
public void close()
{
    DBHelper.close();
}

//---insert a record into the database---
public long insertRecord(String name, String amount, String duedate)
{
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_NAME, name);
    initialValues.put(KEY_AMOUNT, amount);
    initialValues.put(KEY_DUEDATE, duedate);
    //return db.insert(DATABASE_TABLE, null, initialValues);
    // Will return NULL POINTER EXCEPTION as db isn't set
    // Replaces commented out line
    return DBHelper.getWritableDatabase().insert(DATABASE_TABLE,
            null,
            initialValues
    );
}

//---deletes a particular record---
public boolean deleteContact(long rowId)
{
    return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}

//---retrieves all the records--- SEE FOLLOWING METHOD
public Cursor getAllRecords()
{SQLiteDatabase db = DBHelper.getWritableDatabase();
    String query ="SELECT * FROM " + DATABASE_TABLE;
    Cursor data = db.rawQuery(query,null);
    return data;
}


//As per getAllRecords but using query convenience method
public Cursor getAllAsCursor() {
    return DBHelper.getWritableDatabase().query(
            DATABASE_TABLE,
            null,null,null,null,null,null
    );
}
public void deleteName(int id, String name){
    SQLiteDatabase db = DBHelper.getWritableDatabase();
    String query = "DELETE FROM " + DATABASE_TABLE + " WHERE "
            + KEY_ROWID + " = '" + id + "'" +
            " AND " + KEY_NAME + " = '" + name + "'";
    Log.d(TAG, "deleteName: query: " + query);
    Log.d(TAG, "deleteName: Deleting " + name + " from database.");
    db.execSQL(query);
}
public Cursor getItemID(String name) {
    SQLiteDatabase db = DBHelper.getWritableDatabase();
    String query = "SELECT " + KEY_ROWID + " FROM " + DATABASE_TABLE +
            " WHERE " + KEY_NAME + " = '" + name + "'";
    Cursor data = db.rawQuery(query, null);
    return data;
}
//---retrieves a particular record--- THIS WILL NOT WORK - NO SUCH TABLE
/* public Cursor getRecord()
{String query1 ="SELECT * FROM" + KEY_TITLE;
    Cursor mCursor = db.rawQuery(query1,null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;
}*/

// Retrieve a row (single) according to id
public Cursor getRecordById(long id) {
    return DBHelper.getWritableDatabase().query(
            DATABASE_TABLE,
            null,
            KEY_ROWID + "=?",
            new String[]{String.valueOf(id)},
            null,null,null
    );
}


//---updates a record---
/* public boolean updateRecord(long rowId, String name, String amount, String duedate)
{
    ContentValues args = new ContentValues();
    args.put(KEY_NAME, name);
    args.put(KEY_AMOUNT, amount);
    args.put(KEY_DUEDATE, duedate);
    String whereclause = KEY_ROWID + "=?";
    String[] whereargs = new String[]{String.valueOf(rowId)};
    // Will return NULL POINTER EXCEPTION as db isn't set
    //return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
    // Replaces commented out line
    return DBHelper.getWritableDatabase().update(DATABASE_TABLE,
            args,
            whereclause,
            whereargs
    ) > 0;
}*/
}

这是我的 Bills.java (MainActivity)

问题:Bills.java 的 ListView 会在单击 ListView 中的项目时显示 Intent ，但它不会放置金额和日期或更新记录。相反，它会保存另一条记录。

解决方案:我想检索它并显示所有(名称、金额、到期日期)，而不是保存另一个记录，而是应该更新它。

package com.example.dhruv.bill;

import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;

import java.util.ArrayList;

public class bills extends AppCompatActivity {
DBAdapter dbAdapter;
ListView mrecycleview;
private static final String TAG ="assignments";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bills);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    mrecycleview =(ListView) findViewById(R.id.mRecycleView);
    dbAdapter = new DBAdapter(this);
    // mlistview();
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab1);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent i = new Intent(getApplicationContext(),Editbills.class);
            startActivity(i);
        }
    });
    mlistview();
}

@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_bills, 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);
}
private void mlistview(){
    Log.d(TAG,"mlistview:Display data in listview");
    Cursor mCursor = dbAdapter.getAllRecords();
    ArrayList<String> listData = new ArrayList<>();
    while (mCursor.moveToNext()){
        listData.add(mCursor.getString(1));
    }
    ListAdapter adapter = new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,listData);
    mrecycleview.setAdapter(adapter);
    mrecycleview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
            String name = adapterView.getItemAtPosition(i).toString();
            Log.d(TAG, "onItemClick: You Clicked on " + name);
            Cursor data = dbAdapter.getItemID(name); //get the id associated with that name
            int itemID = -1;
            while(data.moveToNext()){
                itemID = data.getInt(0);
            }
            if(itemID > -1){
                Log.d(TAG, "onItemClick: The ID is: " + itemID);
                Intent editScreenIntent = new Intent(bills.this, Editbills.class);
                editScreenIntent.putExtra("id",itemID);
                editScreenIntent.putExtra("name",name);
                startActivity(editScreenIntent);

            }
            else{

            }
        }
    });


}
}

这是我的 editbills.java 代码

package com.example.dhruv.bill;

import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class Editbills extends AppCompatActivity {
Button button;
private static final String Tag= "assignments";
DBAdapter db = new DBAdapter(this);
private String selectedName;
private int selectedID;
DBAdapter dbAdapter;
private EditText editText,editText2,editText3;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_editbills);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    button=(Button)findViewById(R.id.button);
    editText =(EditText)findViewById(R.id.editText);
    editText2=(EditText)findViewById(R.id.editText2);
    editText3 =(EditText)findViewById(R.id.editText3);
    //get the intent extra from the ListDataActivity
    Intent receivedIntent = getIntent();

    //now get the itemID we passed as an extra
    selectedID = receivedIntent.getIntExtra("id",-1); //NOTE: -1 is just the default value

    //now get the name we passed as an extra
    selectedName = receivedIntent.getStringExtra("name");

    //set the text to show the current selected name
    editText.setText(selectedName);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Log.d("test", "adding");
            db.open();
            long id = db.insertRecord(editText.getText().toString(), editText2.getText().toString(), editText3.getText().toString());
            db.close();
            Toast.makeText(Editbills.this," Added", Toast.LENGTH_LONG).show();
            Intent q = new Intent(getApplicationContext(),bills.class);
            startActivity(q);

        }
    });
}
@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_bills, 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_Delete) {
        db.deleteName(selectedID,selectedName);
        editText.setText("");
        Toast.makeText(this, "Deleted", Toast.LENGTH_SHORT).show();
        Intent p = new Intent(getApplicationContext(),bills.class);
        startActivity(p);
        return true;

    }

    return super.onOptionsItemSelected(item);
}

}

Answer 1

而不是DBHelper.getWritableDatabase().insert(DATABASE_TABLE, null,initialValues);在DBHelper的insertRecord函数中，应该是DBHelper.getWritableDatabase().update("markers", valores, where, whereArgs);