我是Java新手，更不用说Android应用开发了。
我试图检索创建的表时，我的应用程序崩溃了。我非常确定代码是可靠的，并且我怀疑我的查询导致了崩溃。所以我有两个可能导致这种情况的查询，CREATE TABLE，然后是getWritableDatabase（）......
我的主要活动是发号施令：
package com.bb.android.breakingbread;
import android.app.Activity;
import android.content.res.Resources;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;
import android.widget.Toast;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class MenuActivity extends Activity {
SQLiteDatabase db;
TableRow tableRow;
private static final int NUM_COL=3;
private static final int NUM_ROW =3;
Button MenuButtons[][]=new Button[NUM_ROW][NUM_COL];
String [][] MenuTable = new String [NUM_ROW][NUM_COL];
String[][] Checker;
double [][] Bill = new double [20][40];
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LayoutMenuSC();
DBhelper db = new DBhelper(this);
Checker=db.getMenu();
}
//============SET LAYOUT OF MENU PAGE (P2)=================================================
public void LayoutMenuSC(){
// layout the buttons on screen
setContentView(R.layout.activitymenu);
TableLayout table =(TableLayout) findViewById(R.id.MenuButtonTable); //need to link this table to xml
for (int row=0; row<NUM_ROW;row++){
//Set new Row in Table
TableRow tableRow= new TableRow(this);
tableRow.setLayoutParams(new TableLayout.LayoutParams(
TableLayout.LayoutParams.MATCH_PARENT,TableLayout.LayoutParams.MATCH_PARENT,1.0F));
table.addView(tableRow);
for (int col=0; col<NUM_COL; col++){
int x,y;
float w;
ImageButton ImButton=new ImageButton(this);
ImButton.setLayoutParams(new TableRow.LayoutParams(
TableRow.LayoutParams.MATCH_PARENT, TableRow.LayoutParams.MATCH_PARENT, 1.0F));
Resources res = getResources();
Drawable drawable = res.getDrawable(R.drawable.ic_launcher);
//Drawable drawable= res.getDrawable("R.drawable." + Photopath);<--------------------
ImButton.setBackground(drawable);
tableRow.addView(ImButton);
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.breaking_bread, 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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
我的DBhelper课程是这样的：
package com.bb.android.breakingbread;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.Toast;
import java.util.LinkedList;
import java.util.List;
public class DBhelper extends SQLiteOpenHelper {
private static final String TAG= DBhelper.class.getSimpleName();
public static final String DB_NAME="BreakingBreadDB6";
public static final int DB_VERSION=1;
private static final String TABLE_MENU = "MenuTable";
private static final String KEY_ID = "id";
private static final String KEY_SW = "SW";
private static final String KEY_PRICE = "Price";
private static final String KEY_PHOTOPATH = "Photopath";
// constructor
public DBhelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
// SQL statement to create menu table
String CREATE_MENU_TABLE = "CREATE TABLE IF NOT EXISTS "+ TABLE_MENU +" ( " + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
KEY_SW + " TEXT, "+
KEY_PRICE +" TEXT, " +
KEY_PHOTOPATH+ " TEXT )";
// create table
db.execSQL(CREATE_MENU_TABLE);
// populate table
AddSWRow("BBQ","15","Path1");
//AddSWRow("Spicy Turky",12,"Path2");
//AddSWRow("Chicken Melt",20,"Path3");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older items table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_MENU);
// create fresh menu table
this.onCreate(db);
}
//====================ADD SANDWICH TO TABLE===================
public void AddSWRow (String SwName, String SwPrice, String SwPhoto){
// 1. get reference to writable DB
SQLiteDatabase db =this.getWritableDatabase();
// 2. create ContentValues to add key "column"/value
ContentValues values = new ContentValues();
values.put(KEY_SW,SwName);
values.put(KEY_PRICE, SwPrice);
values.put(KEY_PHOTOPATH, SwPhoto);
// 3. insert
db.insert(TABLE_MENU,null,values); // key/value -> keys = column names/ values = column values
// 4. close*/
db.close();
}
//===================GET MENU================================
public String[][] getMenu() {
// List<Menu> Menu = new LinkedList<Menu>();
String MenuArray[][] = new String[50][4];
//0. initiatlise array with EOF..
for (int i=0; i<50;i++){
for (int j=0; j<4;j++){
MenuArray[i][j]="EOF";
}
}
// 1. build the query
String query = "SELECT * FROM " + TABLE_MENU;
// 2. get reference to writable DB
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(query, null);
// 3. go over each row
Menu menu = null;
int i;
i=0;
if (cursor != null){
cursor.moveToFirst();
/*while (cursor.isAfterLast() == false) {
MenuArray[i][0]=Integer.parseInt(cursor.getString(0));
MenuArray[i][1]=cursor.getString(1);
MenuArray[i][2]=cursor.getString(2);
MenuArray[i][3]=cursor.getString(3);
i++;
cursor.moveToNext();
}*/
cursor.close();
}
return MenuArray;
}
}
任何建议？
答案 0 :(得分：2)
您无法递归调用getWritableDatabase()。
您的addSWRow()来电getWritableDatabase()，您在数据库帮助addSWRow()中呼叫onCreate()，onCreate()触发getWritableDatabase()。
移除addSWRow()来电，或将SQLiteDatabase从onCreate()传递给它，而不是在那里拨打getWritableDatabase()。