我正在从 SQLite 数据库获取信息并通过 ListView 显示它。在 ListView 上方，我有一个微调器，其中包含在 XML 中创建的各种选项:
<Spinner
android:id="@+id/categoryChoose"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="5dip"
android:entries="@array/catergory_arrays" />
微调值数组:
<string-array name="catergory_arrays">
<item>Select category here:</item>
<item>Fridge / Freezer</item>
<item>Canned Food</item>
<item>Fruit</item>
<item>Vegetable</item>
</string-array>
根据微调器的位置，我想设置一个不同的查询，然后显示在 ListView 中。当前代码:
显示数据库信息的类(CurrentItems):
package com.example.fooditemmonitor;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.View;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Spinner;
public class CurrentItems extends Activity {
ItemDatabase db;
Context context;
Button addButton, editButton;
ListView listView;
int spinnerID;
// the table that displays the data
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.current_inventory);
db = new ItemDatabase(this);
// create references and listeners for the GUI interface
setupViews();
// make the buttons clicks perform actions
addButtonListeners();
displaySearch();
}
private void setupViews() {
// bring up current database items
listView = (ListView) findViewById(R.id.dbListView);
// THE BUTTONS
addButton = (Button) findViewById(R.id.scanCurrent);
editButton = (Button) findViewById(R.id.editItemCurrent);
}
private void addButtonListeners() {
addButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(CurrentItems.this, AddItem.class));
}
});
editButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(CurrentItems.this, EditItems.class));
}
});
}
public int getSelectedItemPosition() {
Spinner selectCat = (Spinner) findViewById(R.id.categoryChoose);
spinnerID = selectCat.getSelectedItemPosition();
return spinnerID;
}
private void displaySearch() {
// TODO Auto-generated method stub
Spinner selectCat = (Spinner) findViewById(R.id.categoryChoose);
spinnerID = selectCat.getSelectedItemPosition();
String catSelected;
final ArrayList<String> items = new ArrayList<String>();
final ArrayAdapter<String> itemArray;
itemArray = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, items);
{
if (getSelectedItemPosition() == 0) {
ArrayList<ArrayList<Object>> data = db.getAllRowsAsArrays();
for (int position = 0; position < data.size(); position++) {
ArrayList<Object> row = data.get(position);
items.add("\nDate: " + row.get(0).toString()
+ "\nTitle: " + row.get(1).toString()
+ "\nQuantity: "
+ Integer.parseInt(row.get(2).toString())
+ "\nCategory:" + row.get(3).toString() + "\n");
itemArray.notifyDataSetChanged();
listView.setAdapter(itemArray);
}
} else if (getSelectedItemPosition() == 1) {
catSelected = "Fridge";
ArrayList<ArrayList<Object>> data = db
.getCategoryOfArrays(catSelected);
for (int position = 0; position < data.size(); position++) {
ArrayList<Object> row = data.get(position);
items.add("\nDate: " + row.get(0).toString()
+ "\nTitle: " + row.get(1).toString()
+ "\nQuantity: "
+ Integer.parseInt(row.get(2).toString())
+ "\nCategory:" + row.get(3).toString() + "\n");
itemArray.notifyDataSetChanged();
listView.setAdapter(itemArray);
}
} else if (getSelectedItemPosition() == 2) {
catSelected = "Can";
ArrayList<ArrayList<Object>> data = db
.getCategoryOfArrays(catSelected);
for (int position = 0; position < data.size(); position++) {
ArrayList<Object> row = data.get(position);
items.add("\nDate: " + row.get(0).toString()
+ "\nTitle: " + row.get(1).toString()
+ "\nQuantity: "
+ Integer.parseInt(row.get(2).toString())
+ "\nCategory:" + row.get(3).toString() + "\n");
itemArray.notifyDataSetChanged();
listView.setAdapter(itemArray);
}
} else if (getSelectedItemPosition() == 3) {
catSelected = "Fruit";
ArrayList<ArrayList<Object>> data = db
.getCategoryOfArrays(catSelected);
for (int position = 0; position < data.size(); position++) {
ArrayList<Object> row = data.get(position);
items.add("\nDate: " + row.get(0).toString()
+ "\nTitle: " + row.get(1).toString()
+ "\nQuantity: "
+ Integer.parseInt(row.get(2).toString())
+ "\nCategory:" + row.get(3).toString() + "\n");
itemArray.notifyDataSetChanged();
listView.setAdapter(itemArray);
}
} else if (getSelectedItemPosition() == 4) {
catSelected = "Vegetable";
ArrayList<ArrayList<Object>> data = db
.getCategoryOfArrays(catSelected);
for (int position = 0; position < data.size(); position++) {
ArrayList<Object> row = data.get(position);
items.add("\nDate: " + row.get(0).toString()
+ "\nTitle: " + row.get(1).toString()
+ "\nQuantity: "
+ Integer.parseInt(row.get(2).toString())
+ "\nCategory:" + row.get(3).toString() + "\n");
itemArray.notifyDataSetChanged();
listView.setAdapter(itemArray);
}
} else {
ArrayList<ArrayList<Object>> data = db.getAllRowsAsArrays();
for (int position = 0; position < data.size(); position++) {
ArrayList<Object> row = data.get(position);
items.add("\nDate: " + row.get(0).toString()
+ "\nTitle: " + row.get(1).toString()
+ "\nQuantity: "
+ Integer.parseInt(row.get(2).toString())
+ "\nCategory:" + row.get(3).toString() + "\n");
itemArray.notifyDataSetChanged();
listView.setAdapter(itemArray);
}
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return super.onCreateOptionsMenu(menu);
}
}
项目数据库:
package com.example.fooditemmonitor;
import java.util.ArrayList;
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 final class ItemDatabase {
// the Activity or Application that is creating an object from this class.
Context context;
// a reference to the database used by this application/object
private SQLiteDatabase db;
// These constants are specific to the database.
private final String DATABASE_NAME = "ItemDatabase.sqlite";
private final int DATABASE_VERSION = 5;
// These constants are specific to the database table.
private final String TABLE_NAME = "foodItems";
private final String COLUMN_NAME_ENTRY_ID = "entryid";
private final String COLUMN_NAME_BARCODE = "barcode";
private final String COLUMN_NAME_TITLE = "title";
private final String COLUMN_NAME_QUANTITY = "quantity";
private final String COLUMN_NAME_DATE = "date";
private final String COLUMN_NAME_CATEGORY = "category";
String SQL_DELETE_ENTRIES = "DROP TABLE IF EXISTS " + TABLE_NAME;
String SQL_CREATE_TABLE = "create table " + TABLE_NAME + " ("
+ COLUMN_NAME_ENTRY_ID
+ " integer primary key autoincrement not null," + COLUMN_NAME_DATE
+ " date," + COLUMN_NAME_BARCODE + " text," + COLUMN_NAME_TITLE
+ " text," + COLUMN_NAME_QUANTITY + " int," + COLUMN_NAME_CATEGORY + " text" + ");";
public ItemDatabase(Context context) {
this.context = context;
// create or open the database
ItemDatabaseHelper helper = new ItemDatabaseHelper(context);
this.db = helper.getWritableDatabase();
}
public void addRow(String rowStringOne, String rowStringTwo,
String rowStringThree, String rowStringFour, int rowIntFive) {
// this is a key value pair holder used by android's SQLite functions
ContentValues values = new ContentValues();
values.put(COLUMN_NAME_DATE, rowStringOne);
values.put(COLUMN_NAME_BARCODE, rowStringTwo);
values.put(COLUMN_NAME_TITLE, rowStringThree);
values.put(COLUMN_NAME_CATEGORY, rowStringFour);
values.put(COLUMN_NAME_QUANTITY, rowIntFive);
// ask the database object to insert the new data
try {
db.insert(TABLE_NAME, null, values);
} catch (Exception e) {
Log.e("DB ERROR", e.toString());
e.printStackTrace();
}
}
public void updateRow(long rowID, String rowStringOne, String rowStringTwo,
String rowStringThree, int rowIntFour) {
// this is a key value pair holder used by android's SQLite functions
ContentValues values = new ContentValues();
values.put(COLUMN_NAME_DATE, rowStringOne);
values.put(COLUMN_NAME_BARCODE, rowStringTwo);
values.put(COLUMN_NAME_TITLE, rowStringThree);
values.put(COLUMN_NAME_QUANTITY, rowIntFour);
// ask the database object to update the database row of given rowID
try {
db.update(TABLE_NAME, values, COLUMN_NAME_ENTRY_ID + "=" + rowID,
null);
} catch (Exception e) {
Log.e("DB Error", e.toString());
e.printStackTrace();
}
}
public void deleteRow(long rowID) {
// ask the database manager to delete the row of given id
try {
db.delete(TABLE_NAME, COLUMN_NAME_ENTRY_ID + "=" + rowID, null);
getAllRowsAsArrays();
} catch (Exception e) {
Log.e("DB ERROR", e.toString());
e.printStackTrace();
}
}
public ArrayList<ArrayList<Object>> getCategoryOfArrays(String category) {
// create an ArrayList that will hold all of the data collected from
// the database.
ArrayList<ArrayList<Object>> dataArrays = new ArrayList<ArrayList<Object>>();
// this is a database call that creates a "cursor" object.
// the cursor object store the information collected from the
// database and is used to iterate through the data.
Cursor cursor;
try {
// ask the database object to create the cursor.
cursor = db.query(TABLE_NAME, new String[] { COLUMN_NAME_DATE,
COLUMN_NAME_TITLE, COLUMN_NAME_QUANTITY, COLUMN_NAME_CATEGORY }, COLUMN_NAME_CATEGORY + "='" + category + "'", null,
null, null, COLUMN_NAME_TITLE + " ASC");
// move the cursor's pointer to position zero.
cursor.moveToFirst();
// if there is data after the current cursor position, add it to the
// ArrayList.
while (cursor.moveToNext()) {
// your content
ArrayList<Object> dataList = new ArrayList<Object>();
dataList.add(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_DATE)));
dataList.add(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_TITLE)));
dataList.add(cursor.getInt(cursor.getColumnIndex(COLUMN_NAME_QUANTITY)));
dataList.add(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_CATEGORY)));
dataArrays.add(dataList);
}
} catch (SQLException e) {
Log.e("DB Error", e.toString());
e.printStackTrace();
}
// return the ArrayList that holds the data collected from the database.
return dataArrays;
}
public ArrayList<ArrayList<Object>> getAllRowsAsArrays() {
// create an ArrayList that will hold all of the data collected from
// the database.
ArrayList<ArrayList<Object>> dataArrays = new ArrayList<ArrayList<Object>>();
// this is a database call that creates a "cursor" object.
// the cursor object store the information collected from the
// database and is used to iterate through the data.
Cursor cursor;
try {
// ask the database object to create the cursor.
cursor = db.query(TABLE_NAME, new String[] { COLUMN_NAME_DATE,
COLUMN_NAME_TITLE, COLUMN_NAME_QUANTITY, COLUMN_NAME_CATEGORY }, null, null,
null, null, COLUMN_NAME_TITLE + " ASC");
// move the cursor's pointer to position zero.
cursor.moveToFirst();
// if there is data after the current cursor position, add it to the
// ArrayList.
while (cursor.moveToNext()) {
// your content
ArrayList<Object> dataList = new ArrayList<Object>();
dataList.add(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_DATE)));
dataList.add(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_TITLE)));
dataList.add(cursor.getInt(cursor.getColumnIndex(COLUMN_NAME_QUANTITY)));
dataList.add(cursor.getString(cursor.getColumnIndex(COLUMN_NAME_CATEGORY)));
dataArrays.add(dataList);
}
} catch (SQLException e) {
Log.e("DB Error", e.toString());
e.printStackTrace();
}
// return the ArrayList that holds the data collected from the database.
return dataArrays;
}
public class ItemDatabaseHelper extends SQLiteOpenHelper {
public ItemDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public void onCreate(SQLiteDatabase db) {
// execute the query string to the database.
db.execSQL(SQL_CREATE_TABLE);
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// This database is only a cache for online data, so its upgrade
// policy is to simply to discard the data and start over
db.execSQL(SQL_DELETE_ENTRIES);
onCreate(db);
}
}
}
已经测试了 getCategoryOfArrays() 并且它有效。当前代码不会返回任何错误，但 Spinner 操作不会更改 ListView 内容。
我们将不胜感激所有帮助!
最佳答案
您的方法 displaySearch() 仅在 Activity 创建时、当微调器位于零位置时调用一次。在 onCreate 中(可能在您的 addButtonListeners() 方法中)在微调器上设置值更改时的监听器。当它出现时，再次调用displaySearch()。
Spinner selectCat = (Spinner) findViewById(R.id.categoryChoose);
selectCat.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener()
{
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id)
{
displaySearch();
}
public void onNothingSelected(AdapterView<?> parent)
{
// Do nothing
}
});
关于java - 更改依赖于 Spinner 行的 SQLite 查询，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21319769/