我让数据显示在一个微调器中，它包含在我的main中创建的食物对象（名称，卡路里），然后使这些对象（现在只是名称）显示在一个旋转器中活动。这项活动实际上将成为更大计划的一部分，最终我希望能够让用户能够“计算”＃34;他们吃掉的卡路里总量加起来所有选择的食物。现在，我只是希望能够让食物出现，这样我才能进一步前进。但是，每当我去运行它，我的应用程序只是崩溃没有错误消息说明问题。如果有人知道我需要做什么，请帮忙。我的代码如下：
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.Toast;
import java.util.List;
public class MainActivity extends ActionBarActivity implements
OnItemSelectedListener {
MyDBHandler dbHandler = new MyDBHandler(this, null, null, 1);
Spinner spinner = (Spinner) findViewById(R.id.spinner);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Foods food1 = new Foods("Apple", "80");
Foods food2 = new Foods("Bagel", "200");
Foods food3 = new Foods("Biscuit", "65" );
Foods food4 = new Foods("Banana", "105");
Foods food5 = new Foods("Beef Roast", "205");
Foods food6 = new Foods("Corn", "60");
Foods food7 = new Foods("Cereal", "120");
Foods food8 = new Foods("Chicken", "240");
Foods food9 = new Foods("Eggs", "105");
Foods food10 = new Foods("Cabbage", "30");
Foods food11 = new Foods("Oatmeal", "160");
Foods food12 = new Foods("Pancake", "60");
Foods food13 = new Foods("Pears", "100");
Foods food14 = new Foods("Pizza", "290");
Foods food15 = new Foods("Ice Cream", "270");
Foods food16 = new Foods("Pork Chop", "335");
Foods food17 = new Foods("Ham", "250");
Foods food18 = new Foods("Ribs", "270");
Foods food19 = new Foods("Popcorn", "55");
Foods food20 = new Foods("Baked Potato", "220");
Foods food21 = new Foods("Rice", "225");
Foods food22 = new Foods("Salad", "85");
Foods food23 = new Foods("Spaghetti", "360");
Foods food24 = new Foods("Bread", "65");
Foods food25 = new Foods("Fish", "175");
dbHandler.addFood(food1);
dbHandler.addFood(food2);
dbHandler.addFood(food3);
dbHandler.addFood(food4);
dbHandler.addFood(food5);
dbHandler.addFood(food6);
dbHandler.addFood(food7);
dbHandler.addFood(food8);
dbHandler.addFood(food9);
dbHandler.addFood(food10);
dbHandler.addFood(food11);
dbHandler.addFood(food12);
dbHandler.addFood(food13);
dbHandler.addFood(food14);
dbHandler.addFood(food15);
dbHandler.addFood(food16);
dbHandler.addFood(food17);
dbHandler.addFood(food18);
dbHandler.addFood(food19);
dbHandler.addFood(food20);
dbHandler.addFood(food21);
dbHandler.addFood(food22);
dbHandler.addFood(food23);
dbHandler.addFood(food24);
dbHandler.addFood(food25);
spinner.setOnItemSelectedListener(this);
loadSpinnerData();
}
private void loadSpinnerData()
{
List<String> foodnames = dbHandler.getFoodNames();
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, foodnames);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(dataAdapter);
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String food = parent.getItemAtPosition(position).toString();
// Showing selected spinner item
Toast.makeText(parent.getContext(), "You selected: " + food,
Toast.LENGTH_LONG).show();
}
}
public class Foods {
private int _id;
public int get_id() {
return _id;
}
public void set_id(int _id) {
this._id = _id;
}
private String name;
private String calories;
public Foods(){
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCalories() {
return calories;
}
public void setCalories(String calories) {
this.calories = calories;
}
public Foods(String foodname, String foodcalories){
this.name = foodname;
this.calories = foodcalories;
}
}
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.Cursor;
import android.content.Context;
import android.content.ContentValues;
import java.util.ArrayList;
import java.util.List;
public class MyDBHandler extends SQLiteOpenHelper {
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "BroncoWellness.db";
public static final String TABLE_FOODS = "food";
public static final String COLUMN_FOOD_ID = "_id";
public static final String COLUMN_FOOD_NAME = "foodname";
public static final String COLUMN_FOOD_CALORIES = "foodcalories";
@Override
public void onCreate(SQLiteDatabase db) {
String Foodquery = "CREATE TABLE " + TABLE_FOODS + "(" +
COLUMN_FOOD_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
COLUMN_FOOD_NAME + " TEXT " +
COLUMN_FOOD_CALORIES + " TEXT " +
");";
db.execSQL(Foodquery);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_FOODS);
onCreate(db);
}
public MyDBHandler(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context,DATABASE_NAME ,factory, DATABASE_VERSION);}
public void addFood(Foods food){
ContentValues values = new ContentValues();
values.put(COLUMN_FOOD_NAME, food.getName());
values.put(COLUMN_FOOD_CALORIES, food.getCalories());
SQLiteDatabase db = getWritableDatabase();
db.insert(TABLE_FOODS,null,values);
db.close();
}
public List<String> getFoodNames(){
List<String> foodnames = new ArrayList<String>();
String selectQuery = "SELECT * FROM " + TABLE_FOODS;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
foodnames.add(cursor.getString(1));
} while (cursor.moveToNext());
}
cursor.close();
db.close();
return foodnames;
}
}
答案 0 :(得分：0)
在您的代码中，您正在onCreate（）方法之外初始化微调器。它应该是这样的 -
Spinner spinner;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
spinner = (Spinner) findViewById(R.id.spinner);
//your code
}
这将解决您的问题。
答案 1 :(得分：0)
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// **Spinner element here**
spinner = (Spinner) findViewById(R.id.spinner);