Question

我有一个包含多个表的SQLite数据库，我想从其中一个表中读取所有内容，并使用它来填充列表，但我不知道当我尝试读取所有数据时应用程序崩溃的原因从表中。

这是我的代码：活性：

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.ListActivity;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;


public class Manage_Groups extends ListActivity implements OnClickListener{

    Button create_group_button;

    DB_Handler db;
    Groups_DB_Adapter groups_db;

    ListView groupsList;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.manage_groups);

        // Initializing the buttons according to their ID
        create_group_button = (Button)findViewById(R.id.create_group_button);

        //Defines listeners for the buttons
        create_group_button.setOnClickListener(this);

        groups_db = new Groups_DB_Adapter(this);

        // Opens the Main DB for read
        db = new DB_Handler(this);
        db.openToRead();

        // Opens the Groups DB for read
        groups_db.openToRead();

        // This is where it crashes...
        Cursor mCursor = groups_db.getAllGroups();
        startManagingCursor(mCursor);
        String[] from = new String[]{Groups_DB_Adapter.GROUP_NAME};
        int[] to = {};
        SimpleCursorAdapter cursorAdapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_1, 
                                    mCursor, from, to = new int[] { android.R.id.text1 });

        setListAdapter(cursorAdapter);
        groupsList = getListView();

        // Listens for a long click, and then pops up a delete dialog
        groupsList.setOnItemLongClickListener(new OnItemLongClickListener() {

            public boolean onItemLongClick(AdapterView<?> arg0, View arg1,
                    int pos, long id) {
                AlertDialog.Builder delete_group_alert = new AlertDialog.Builder(Manage_Groups.this);
                delete_group_alert.setMessage("Are you sure you want to delete this group?");
                final int positionToRemove = pos;

                // No - closes the dialog and does nothing
                delete_group_alert.setNegativeButton("No", null);

                // Yes - Deletes the clicked group from the DB
                delete_group_alert.setPositiveButton("Yes", new AlertDialog.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        groups_db.deleteGroup(positionToRemove);
                    }});
                delete_group_alert.show();

                return true;
            }
        });
    }

    //@Override
    public void onClick(View src) {
        Intent i;
        switch (src.getId())
        {
        case R.id.create_group_button:

            finish();

            i = new Intent(this, Create_Group.class);
            startActivity(i);
            break;  
    }

}
}

群组适配器：

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 Groups_DB_Adapter {

    // A reference to the database used by this application/object
    private SQLiteDatabase db;
    private OpenHelper db_open_helper;

    // Groups table
    static final String GROUPS_TABLE_NAME = "groups_table";
    static final String GROUP_ID = "group_id";
    static final String GROUP_NAME = "group_name";

    // The Activity or Application that is creating an object from this class
    private final Context context;

    private static class OpenHelper extends SQLiteOpenHelper {

        OpenHelper(Context context) {
            super(context, DB_Handler.DATABASE_NAME, null, DB_Handler.DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        }
    }

    public Groups_DB_Adapter(Context ctx) {
        this.context = ctx;
    }

    // Opens the DB for write
    public Groups_DB_Adapter openToWrite() throws SQLException {
        this.db_open_helper = new OpenHelper(this.context);
        this.db = this.db_open_helper.getWritableDatabase();
        return this;
    }

    // Opens the DB for read
    public Groups_DB_Adapter openToRead() throws SQLException {
        this.db_open_helper = new OpenHelper(this.context);
        this.db = this.db_open_helper.getReadableDatabase();
        return this;
    }

    // Closes the DB
    public void close() {
        this.db_open_helper.close();
    }

    // Adds a new group
    public void addNewGroup(String groupName)
    {
        // this is a key value pair holder used by android's SQLite functions
        ContentValues values = new ContentValues();
        values.put(GROUP_NAME, groupName);

        // ask the database object to insert the new data 
        try{db.insert(GROUPS_TABLE_NAME, null, values);}
        catch(Exception e)
        {
            Log.e("DB ERROR", e.toString());
            e.printStackTrace();
        }
    }

    // Deletes a specific group
    public boolean deleteGroup(long rowId) {

        return this.db.delete(GROUPS_TABLE_NAME, GROUP_ID + "=" + rowId, null) > 0;
    }

    // Returns a Cursor with all the groups
    public Cursor getAllGroups() {

        return this.db.query(GROUPS_TABLE_NAME, new String[] { GROUP_ID,
                GROUP_NAME }, null, null, null, null, null);
    }

    // Returns a specific group
    public Cursor getGroup(long rowId) throws SQLException {

        Cursor mCursor =

        this.db.query(true, GROUPS_TABLE_NAME, new String[] { GROUP_ID, GROUP_NAME}, 
                GROUP_ID + "=" + rowId, null, null, null, null, null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor;
    }

    // Updates a group
    public boolean updateGroup(long rowId, String name){
        ContentValues args = new ContentValues();
        args.put(GROUP_NAME, name);

        return this.db.update(GROUPS_TABLE_NAME, args, GROUP_ID + "=" + rowId, null) >0; 
    }

}

主DB处理程序：

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteStatement;
import android.util.Log;

import java.util.ArrayList;
import java.util.List;

public class DB_Handler {

    // The database's name and version
    public static final  String DATABASE_NAME = "my_db";
    public static final int DATABASE_VERSION = 2;

    // A reference to the database used by this application/object
    static SQLiteDatabase db;
    private OpenHelper db_open_helper;

    // The Activity or Application that is creating an object from this class
    private static Context context;

    // Contacts table
    static final String CONTACTS_TABLE_NAME = "contacts_table";
    static final String CONTACT_PHONE_NUMBER = "contact_phone_number";
    static final String CONTACT_NAME = "contact_name";
    private static final String CONTACTS_TABLE_CREATE = "CREATE TABLE " + CONTACTS_TABLE_NAME +
                                                        " (" +
                                                        CONTACT_PHONE_NUMBER + " INTEGER, " +
                                                        CONTACT_NAME + " TEXT);";

    // Groups table
    static final String GROUPS_TABLE_NAME = "groups_table";
    static final String GROUP_ID = "group_id";
    static final String GROUP_NAME = "group_name";
    private static final String GROUPS_TABLE_CREATE = "CREATE TABLE " + GROUPS_TABLE_NAME +
                                                      " (" +
                                                      GROUP_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                                                      GROUP_NAME + " TEXT);";

    // Contacts <-> Groups Relations table
    static final String CONTACT2GROUP_TABLE_NAME = "contact2group_table";
    private static final String CONTACT2GROUP_TABLE_CREATE = "CREATE TABLE " + CONTACT2GROUP_TABLE_NAME +
                                                             " (" +
                                                             CONTACT_PHONE_NUMBER + " INTEGER, " +
                                                             GROUP_ID + " INTEGER);";

    // Constructor to simplify Business logic access to the repository 
    public DB_Handler(Context context) {
        DB_Handler.context = context;
    }

    public DB_Handler openToRead() throws android.database.SQLException {
        db_open_helper = new OpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
        db = db_open_helper.getReadableDatabase();
        return this;    
    }

    public DB_Handler openToWrite() throws android.database.SQLException {
        db_open_helper = new OpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
        db = db_open_helper.getWritableDatabase();
        return this;    
    }

    public void close(){
        db_open_helper.close();
    }


    public class OpenHelper extends SQLiteOpenHelper {

        public OpenHelper(Context context, String name,
                CursorFactory factory, int version) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        // Creates the DB
        @Override
        public void onCreate(SQLiteDatabase db) {
            // Creating the Contacts table
            db.execSQL(CONTACTS_TABLE_CREATE);

            // Creating the Groups table
            db.execSQL(GROUPS_TABLE_CREATE);

            // Creating the Contact2Group table
            db.execSQL(CONTACT2GROUP_TABLE_CREATE);
        }

        // Upgrades the DB if a newer version is available
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS " + CONTACTS_TABLE_NAME);
            db.execSQL("DROP TABLE IF EXISTS " + GROUPS_TABLE_NAME);
            db.execSQL("DROP TABLE IF EXISTS " + CONTACT2GROUP_TABLE_NAME);
            onCreate(db);
        }
    }

}

编辑：添加了LOG 这是日志：

07-02 17:05:35.340: E/AndroidRuntime(1281): FATAL EXCEPTION: main
07-02 17:05:35.340: E/AndroidRuntime(1281): java.lang.RuntimeException: Unable to start activity ComponentInfo{meetapp.pack/meetapp.pack.Manage_Groups}: android.database.sqlite.SQLiteException: no such table: groups_table: , while compiling: SELECT group_id, group_name FROM groups_table
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.app.ActivityThread.access$600(ActivityThread.java:123)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.os.Looper.loop(Looper.java:137)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.app.ActivityThread.main(ActivityThread.java:4424)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at java.lang.reflect.Method.invokeNative(Native Method)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at java.lang.reflect.Method.invoke(Method.java:511)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at dalvik.system.NativeStart.main(Native Method)
07-02 17:05:35.340: E/AndroidRuntime(1281): Caused by: android.database.sqlite.SQLiteException: no such table: groups_table: , while compiling: SELECT group_id, group_name FROM groups_table
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:68)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteProgram.compileSql(SQLiteProgram.java:143)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteProgram.compileAndbindAllArgs(SQLiteProgram.java:361)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:127)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:94)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:53)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1564)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1449)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1405)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1485)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at meetapp.pack.Groups_DB_Adapter.getAllGroups(Groups_DB_Adapter.java:127)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at meetapp.pack.Manage_Groups.onCreate(Manage_Groups.java:53)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.app.Activity.performCreate(Activity.java:4465)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
07-02 17:05:35.340: E/AndroidRuntime(1281):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
07-02 17:05:35.340: E/AndroidRuntime(1281):     ... 11 more

有什么想法吗？

谢谢！

Answer 1

Cursor mCursor = groups_db.getAllGroups();

这不起作用，因为您可以错误地看到您没有创建groups_table。

@Override
public void onCreate(SQLiteDatabase db) {

}

您的onCreate也onUpgrade方法为空，且您的 groups_table 从未创建过。

因此，您需要在 Groups_DB_Adapter 类的内部类中调用db.execSQL(GROUPS_TABLE_CREATE);。

从多表SQLite DB填充Listview

1 个答案: