SQLite 数据库到 listView？
SQLite Database to listView?
我正在尝试从我的数据库中的列 ITEMS 中获取数据，以便在您单击 add 按钮时显示在 Items listView 中。当您单击 add 按钮时，它只是将一个项目保存在数据库的一列中。我将不胜感激！
主要Javaclass(New_Recipe)
public class New_Recipe extends AppCompatActivity {
Button add,done,display;
EditText Recipe_Name,Recipe_Item,Recipe_Steps;
String search;
WebView webView;
DatabaseHelper databaseHelper;
ListView Items;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new__recipe);
databaseHelper = new DatabaseHelper(this);
setTitle("New Recipe");
add = (Button) findViewById(R.id.button2);
done = (Button) findViewById(R.id.button);
Recipe_Name = (EditText) findViewById(R.id.editText);
Recipe_Item = (EditText) findViewById(R.id.editText2);
Recipe_Steps = (EditText) findViewById(R.id.editText3);
webView = (WebView) findViewById(R.id.webView);
display = (Button) findViewById(R.id.button3);
Items = (ListView) findViewById(R.id.listView);
AddData();
viewAll();
}
public void AddData() {
done.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
boolean inserted = databaseHelper.insertData1(Recipe_Name.getText().toString(),
Recipe_Steps.getText().toString());
if (inserted == true)
Log.d("Database", "Data successfully inserted!");
else Log.d("Database","Data did not insert!");
}
});
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
boolean inserted = databaseHelper.insertData2(Recipe_Item.getText().toString());
if (inserted == true)
Log.d("Database", "Data successfully inserted!");
else Log.d("Database","Data did not insert!");
}
});
}
public void viewAll() {
display.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Cursor res = databaseHelper.getAllData();
if (res.getCount() == 0) {
showMessage("Error","No Data found!");
return;
}
StringBuffer stringBuffer = new StringBuffer();
while (res.moveToNext()) {
stringBuffer.append("Names :"+res.getString(0)+"\n");
stringBuffer.append("Items :"+res.getString(1)+"\n");
stringBuffer.append("Steps :"+res.getString(2)+"\n\n");
}
showMessage("Success!",stringBuffer.toString());
}
});
}
public void showMessage(String title,String message) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setCancelable(true);
builder.setTitle(title);
builder.setMessage(message);
builder.show();
}
public void onSearch(View v) {
search = "Recipes";
webView.loadUrl("https://www.google.com/search?q="+search);
}
@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_new__recipe, 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);
}
}
数据库Javaclass(DatabaseHelper)
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "Recipes.db";
public static final String TABLE_NAME = " Recipe_Table";
public static final String COL1 = "NAME";
public static final String COL2 = "ITEMS";
public static final String COL3 = "STEPS";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
Log.d("Database", "Database should be made!");
}
@Override
public void onCreate (SQLiteDatabase db){
db.execSQL("create table " + TABLE_NAME + " (NAME TEXT PRIMARY KEY,ITEMS TEXT,STEPS TEXT)");
Log.d("Database", "Database should be made!, Again");
}
@Override
public void onUpgrade (SQLiteDatabase db,int oldVersion, int newVersion){
db.execSQL("DROP TABLE IF EXISTS" + TABLE_NAME);
Log.d("Database", "Table exists");
onCreate(db);
}
public boolean insertData1(String name,String steps) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL1, name);
contentValues.put(COL3, steps);
long result = db.insert(TABLE_NAME,null,contentValues);
if (result == -1)
return false;
else
return true;
}
public boolean insertData2(String items) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL2, items);
long result = db.insert(TABLE_NAME,null,contentValues);
if (result == -1)
return false;
else
return true;
}
public Cursor getAllData() {
SQLiteDatabase db = this.getWritableDatabase();
Cursor res = db.rawQuery("select * from "+TABLE_NAME,null);
return res;
}
public Cursor getItemData() {
SQLiteDatabase db = this.getReadableDatabase();
Cursor res = db.rawQuery("select"+COL2+"from"+TABLE_NAME,null);
return res;
}
}
您需要创建一个适配器，列表视图可以从中提取数据。您会将来自 getAllData() 调用的数据传递给适配器，然后列表视图将显示该适配器。
如果您还没有这样做，您可以创建一个自定义 class 来扩展基础适配器，正确实施方法，然后您只需担心数据。
首先，我总是喜欢构建一个 class 来存储从数据库中检索到的数据。一些简单的东西，例如：
public class ItemObject {
// Instance variables.
private String mName, mItem, mStep;
// Constructor.
public ItemObject(String name, String item, String step) {
mName = name;
mItem = item;
mStep = step;
}
// Create getters for each item.
public String getName() { /*...*/ }
public String getItem() { /*...*/ }
public String getStep() { /*...*/ }
}
现在您有一个对象可以存储从数据库中检索到的项目 table。在调用 getAllData() 后的 while 循环中，您在那里创建了 ItemObject。
例如：
List<ItemObject> itemObjectList = new ArrayList<>();
while (res.moveToNext()) {
// Extract values from the cursor.
String name = res.getString(0);
String item = res.getString(1);
String step = res.getString(2);
// Create the ItemObject and add it to the list.
ItemObject item = new ItemObject(name, item, step);
// Add it to the list.
itemObjectList.add(item);
}
现在，您将拥有一个可以直接传递给适配器的项目列表。
public class ItemsListAdapter extends BaseAdapter {
// Instance variables.
private Context mContext;
private List<ItemObject> mItemObjectList;
// Constructor.
public ItemsListAdapter(Context context, List<itemObjectList> itemObjectList) {
mContext = context;
mItemObjectList = itemObjectList;
}
@Override
public int getCount() {
return mItemObjectList.size();
}
@Override
public Object getItem(int position) {
return mItemObjectList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// Inflate your layout for each row here. I wont include list view
// optimization here, as you should look it up, its documentation
// is readily available.
LayoutInflater inflater = LayoutInflater.from(mContext);
// Inflate the layout.
View layout = inflater.inflate(R.layout.<your_list_view_row_layout>, null);
// Reference the views inside the layout that will display each value. (Name, Item, Step);
TextView nameView = (TextView) layout.findViewById(R.id.<your_text_view_id>);
// Do this for each view.
// Now retrieve your data from the array list.
ItemObject item = (ItemObject) getItem(position);
// Now you have your item and the 3 values associated with it.
// Set the values in the UI.
nameView.setText(item.getName());
// Return the view.
return layout;
}
// Use this method to modify the data in the list view.
// It's an ArrayList so simply add or remove elements, clear it, etc.
public List<ItemObject> getAdapterList() {
return mItemObjectList;
}
}
要更新列表视图中的项目，请调用 getAdapterList() 并修改返回的 ArrayList 中的项目。修改后，您必须通过在适配器本身上调用 notifyDataSetChanged() 使列表无效。
希望这能为您指明正确的方向。
真正的 Android 方法是结合使用 ContentProvider 和 CursorAdapter。
Android 已经有办法从查询中获取 Cursor 并将数据放入 ListView： CursorAdapter class。您只需覆盖 getView() 即可为您的列表创建项目视图。
以下是自定义 ContentProvider 的用途：当您创建内容提供商 URI 并查询它以获取 Cursor 时，会设置 DataObserver，因此当您通过 ContentProvider 使用该 URI insert/delete/update 数据，Cursor 将收到数据已更改的通知，并将 re-query 数据。当在 CursorAdapter 上设置 Cursor 时，适配器将 也 看到游标数据已更改并调用 notifyDataSetChanged().
所以最终结果是，当您添加一条记录时，您的 ListView 自动 使用当前数据刷新。
关于Content Provider的介绍，参考这篇文章：Content Providers | Android Developers。
我正在尝试从我的数据库中的列 ITEMS 中获取数据，以便在您单击 add 按钮时显示在 Items listView 中。当您单击 add 按钮时，它只是将一个项目保存在数据库的一列中。我将不胜感激！
主要Javaclass(New_Recipe)
public class New_Recipe extends AppCompatActivity {
Button add,done,display;
EditText Recipe_Name,Recipe_Item,Recipe_Steps;
String search;
WebView webView;
DatabaseHelper databaseHelper;
ListView Items;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new__recipe);
databaseHelper = new DatabaseHelper(this);
setTitle("New Recipe");
add = (Button) findViewById(R.id.button2);
done = (Button) findViewById(R.id.button);
Recipe_Name = (EditText) findViewById(R.id.editText);
Recipe_Item = (EditText) findViewById(R.id.editText2);
Recipe_Steps = (EditText) findViewById(R.id.editText3);
webView = (WebView) findViewById(R.id.webView);
display = (Button) findViewById(R.id.button3);
Items = (ListView) findViewById(R.id.listView);
AddData();
viewAll();
}
public void AddData() {
done.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
boolean inserted = databaseHelper.insertData1(Recipe_Name.getText().toString(),
Recipe_Steps.getText().toString());
if (inserted == true)
Log.d("Database", "Data successfully inserted!");
else Log.d("Database","Data did not insert!");
}
});
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
boolean inserted = databaseHelper.insertData2(Recipe_Item.getText().toString());
if (inserted == true)
Log.d("Database", "Data successfully inserted!");
else Log.d("Database","Data did not insert!");
}
});
}
public void viewAll() {
display.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Cursor res = databaseHelper.getAllData();
if (res.getCount() == 0) {
showMessage("Error","No Data found!");
return;
}
StringBuffer stringBuffer = new StringBuffer();
while (res.moveToNext()) {
stringBuffer.append("Names :"+res.getString(0)+"\n");
stringBuffer.append("Items :"+res.getString(1)+"\n");
stringBuffer.append("Steps :"+res.getString(2)+"\n\n");
}
showMessage("Success!",stringBuffer.toString());
}
});
}
public void showMessage(String title,String message) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setCancelable(true);
builder.setTitle(title);
builder.setMessage(message);
builder.show();
}
public void onSearch(View v) {
search = "Recipes";
webView.loadUrl("https://www.google.com/search?q="+search);
}
@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_new__recipe, 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);
}
}
数据库Javaclass(DatabaseHelper)
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "Recipes.db";
public static final String TABLE_NAME = " Recipe_Table";
public static final String COL1 = "NAME";
public static final String COL2 = "ITEMS";
public static final String COL3 = "STEPS";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
Log.d("Database", "Database should be made!");
}
@Override
public void onCreate (SQLiteDatabase db){
db.execSQL("create table " + TABLE_NAME + " (NAME TEXT PRIMARY KEY,ITEMS TEXT,STEPS TEXT)");
Log.d("Database", "Database should be made!, Again");
}
@Override
public void onUpgrade (SQLiteDatabase db,int oldVersion, int newVersion){
db.execSQL("DROP TABLE IF EXISTS" + TABLE_NAME);
Log.d("Database", "Table exists");
onCreate(db);
}
public boolean insertData1(String name,String steps) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL1, name);
contentValues.put(COL3, steps);
long result = db.insert(TABLE_NAME,null,contentValues);
if (result == -1)
return false;
else
return true;
}
public boolean insertData2(String items) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL2, items);
long result = db.insert(TABLE_NAME,null,contentValues);
if (result == -1)
return false;
else
return true;
}
public Cursor getAllData() {
SQLiteDatabase db = this.getWritableDatabase();
Cursor res = db.rawQuery("select * from "+TABLE_NAME,null);
return res;
}
public Cursor getItemData() {
SQLiteDatabase db = this.getReadableDatabase();
Cursor res = db.rawQuery("select"+COL2+"from"+TABLE_NAME,null);
return res;
}
}
您需要创建一个适配器，列表视图可以从中提取数据。您会将来自 getAllData() 调用的数据传递给适配器，然后列表视图将显示该适配器。
如果您还没有这样做，您可以创建一个自定义 class 来扩展基础适配器，正确实施方法，然后您只需担心数据。
首先，我总是喜欢构建一个 class 来存储从数据库中检索到的数据。一些简单的东西，例如：
public class ItemObject {
// Instance variables.
private String mName, mItem, mStep;
// Constructor.
public ItemObject(String name, String item, String step) {
mName = name;
mItem = item;
mStep = step;
}
// Create getters for each item.
public String getName() { /*...*/ }
public String getItem() { /*...*/ }
public String getStep() { /*...*/ }
}
现在您有一个对象可以存储从数据库中检索到的项目 table。在调用 getAllData() 后的 while 循环中，您在那里创建了 ItemObject。
例如：
List<ItemObject> itemObjectList = new ArrayList<>();
while (res.moveToNext()) {
// Extract values from the cursor.
String name = res.getString(0);
String item = res.getString(1);
String step = res.getString(2);
// Create the ItemObject and add it to the list.
ItemObject item = new ItemObject(name, item, step);
// Add it to the list.
itemObjectList.add(item);
}
现在，您将拥有一个可以直接传递给适配器的项目列表。
public class ItemsListAdapter extends BaseAdapter {
// Instance variables.
private Context mContext;
private List<ItemObject> mItemObjectList;
// Constructor.
public ItemsListAdapter(Context context, List<itemObjectList> itemObjectList) {
mContext = context;
mItemObjectList = itemObjectList;
}
@Override
public int getCount() {
return mItemObjectList.size();
}
@Override
public Object getItem(int position) {
return mItemObjectList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// Inflate your layout for each row here. I wont include list view
// optimization here, as you should look it up, its documentation
// is readily available.
LayoutInflater inflater = LayoutInflater.from(mContext);
// Inflate the layout.
View layout = inflater.inflate(R.layout.<your_list_view_row_layout>, null);
// Reference the views inside the layout that will display each value. (Name, Item, Step);
TextView nameView = (TextView) layout.findViewById(R.id.<your_text_view_id>);
// Do this for each view.
// Now retrieve your data from the array list.
ItemObject item = (ItemObject) getItem(position);
// Now you have your item and the 3 values associated with it.
// Set the values in the UI.
nameView.setText(item.getName());
// Return the view.
return layout;
}
// Use this method to modify the data in the list view.
// It's an ArrayList so simply add or remove elements, clear it, etc.
public List<ItemObject> getAdapterList() {
return mItemObjectList;
}
}
要更新列表视图中的项目，请调用 getAdapterList() 并修改返回的 ArrayList 中的项目。修改后，您必须通过在适配器本身上调用 notifyDataSetChanged() 使列表无效。
希望这能为您指明正确的方向。
真正的 Android 方法是结合使用 ContentProvider 和 CursorAdapter。
Android 已经有办法从查询中获取 Cursor 并将数据放入 ListView： CursorAdapter class。您只需覆盖 getView() 即可为您的列表创建项目视图。
以下是自定义 ContentProvider 的用途：当您创建内容提供商 URI 并查询它以获取 Cursor 时，会设置 DataObserver，因此当您通过 ContentProvider 使用该 URI insert/delete/update 数据，Cursor 将收到数据已更改的通知，并将 re-query 数据。当在 CursorAdapter 上设置 Cursor 时，适配器将 也 看到游标数据已更改并调用 notifyDataSetChanged().
所以最终结果是，当您添加一条记录时，您的 ListView 自动 使用当前数据刷新。
关于Content Provider的介绍，参考这篇文章：Content Providers | Android Developers。