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私はデータベースからデータを取得し、それをリストビューにSQlite保存していますが、入力してアプリケーションフォースを閉じています。何が間違いなのか理解できません。誰かが間違いを犯していることを教えてください。array listnull pointer exceptionlogcat

ここに私のアクティビティクラスコードがあります:

package testing.testapp;

import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;


public class Administrator extends Activity {

    List<User> usersList;
    SimpleCursorAdapter cursorAdapter;
    List<User> userList;
    TextView fullName;
    TextView cellNumber;
    ListView list;
    AdministratorAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.administrator);

        list=(ListView)findViewById(R.id.fullname);

        DatabaseHandler h = new DatabaseHandler(this);
        usersList = h.getAllUsers();

        adapter = new AdministratorAdapter(this, R.layout.row, userList);
        list.setAdapter(adapter);



    }


    public class AdministratorAdapter extends ArrayAdapter<User>
    {
        Context context;
        Administrator holder;
        int layoutResourceId;
        List<User> userList;


        public AdministratorAdapter(Context context, int layoutResourceId,List<User> userList)
        {
            super(context, layoutResourceId, userList);         
            this.context=context;
            this.layoutResourceId=layoutResourceId;
            this.userList=userList;
        }


        @Override
        public View getView(int position,View convertView,ViewGroup parent)
        {
            View row=convertView;

            if(row==null)
            {
                LayoutInflater inflater=((Activity)context).getLayoutInflater();
                row=inflater.inflate(layoutResourceId, parent,false);

                holder=new Administrator();
                holder.fullName=(TextView)row.findViewById(R.id.fulname);
                holder.cellNumber=(TextView)row.findViewById(R.id.mobile);

                row.setTag(holder);
            }
            else
            {
                holder=(Administrator)row.getTag();
            }
            holder.fullName.setText(userList.get(position).getUserName());
            holder.cellNumber.setText(userList.get(position).getPassword());    
            return row;
        }

ここに私のデータベース処理クラスがあります：

package testing.testapp;

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

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;

public class DatabaseHandler extends SQLiteOpenHelper {

    public static final int DATABASE_VERSION = 4;

    public static final String DATABASE_NAME = "usersManager";

    public static final String TABLE_USERS = "users";

    public static final String KEY_USER_ID = "_id";

    public static final String KEY_USERNAME = "username";

    public static final String KEY_PASSWORD = "password";

    public static final String KEY_ROLE = "role";

    public static final String KEY_GPA = "gpa";

    public static final String KEY_FIRST_NAME = "firstname";

    public static final String KEY_LAST_NAME = "lastname";

    public static final String KEY_GENDER = "gender";

    public static final String KEY_CELL_NUMBER = "cellnumber";




    public DatabaseHandler(Context context)
    {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }


    @Override
    public void onCreate(SQLiteDatabase db)
    {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_USERS);
        String CREATE_USERS_TABLE = "CREATE TABLE " + TABLE_USERS + "("
               + KEY_USER_ID + " INTEGER PRIMARY KEY," + KEY_USERNAME + " TEXT,"
               + KEY_PASSWORD +" TEXT," + KEY_ROLE + " TEXT," + KEY_GPA + " TEXT,"
               + KEY_FIRST_NAME + " TEXT," + KEY_LAST_NAME + " TEXT," 
               + KEY_GENDER + " TEXT," + KEY_CELL_NUMBER + " TEXT" + ")";

//       String CREATE_USERS_TABLE = "create table users ("
//          + "_id integer  primary key autoincrement, "
//          + "username  string  not null, "
//          + "password string  not null, "
//          + ");";

        db.execSQL(CREATE_USERS_TABLE);
    }


    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
    {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_USERS);

        onCreate(db);

    }

    public void addUser(User user)
    {
        SQLiteDatabase db = this.getWritableDatabase();
        int f =db.getVersion();

        Log.d("version", Integer.toString(f));
        ContentValues values = new ContentValues();
        values.put(KEY_USERNAME,user.getUserName());
        values.put(KEY_PASSWORD, user.getPassword());
        values.put(KEY_ROLE, user.getRole());

        db.insert(TABLE_USERS, null, values);
        db.close();

    }


    public int Login(String username,String password,String role)
    {
        try
        {
            SQLiteDatabase db = this.getWritableDatabase();
            int i = 0;
            Cursor c = null;
            String query = "SELECT * FROM " + TABLE_USERS + " WHERE " + KEY_USERNAME+ "='" + username +"'" + " AND " +KEY_PASSWORD+ "='"+password+"'" + " AND " +KEY_ROLE+ "='"+role+"'" ; 
            //String query = "SELECT * FROM users WHERE username = '"+username+"' AND password = '"+password+"'";
            //String query = "SELECT * FROM USERS";
            c = db.rawQuery(query, null);
            c.moveToFirst();
            i = c.getCount(); 
            c.close(); 
            db.close();
            return i;
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        return 0;
    }

    public void AddInfo(User user)
    {
        SQLiteDatabase db = this.getWritableDatabase();
        int f =db.getVersion();

        Log.d("version", Integer.toString(f));
        ContentValues values = new ContentValues();
        values.put(KEY_FIRST_NAME,user.getFirstName());
        values.put(KEY_LAST_NAME, user.getLastName());
        values.put(KEY_GENDER, user.getGender());
        values.put(KEY_GPA,user.getGpa());
        values.put(KEY_CELL_NUMBER, user.getCellNumber());

        db.insert(TABLE_USERS, null, values);
        db.close();
    }

    public List<User> getAllUsers()
    {
        List<User> usersList = new ArrayList<User>();

        String query = "SELECT * FROM " + TABLE_USERS ;
        //+ " WHERE " + KEY_ROLE+ "=Student"

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(query, null);
        //return cursor;
        if(cursor.moveToFirst())
        {
            do
            {
            User user = new User();
            user.setUserId(Integer.parseInt(cursor.getString(0)));
            user.setUserName(cursor.getString(1));
            user.setPassword(cursor.getString(2));
            user.setRole(cursor.getString(3));
            user.setGpa(cursor.getString(4));
            user.setFirstName(cursor.getString(5));
            user.setLastName(cursor.getString(6));
            user.setGender(cursor.getString(7));
            user.setCellNumber(cursor.getString(8));

            usersList.add(user);
            }while(cursor.moveToNext());

        }
        db.close();
        return usersList;

    }

    public User getUserDetail(String username)
    {
        SQLiteDatabase db = this.getWritableDatabase();

        //String query = "SELECT " + KEY_USERNAME+" , " + KEY_PASSWORD + " FROM " + TABLE_USERS + " WHERE " + KEY_USERNAME + " = '" + username + "' ";
        String query = "SELECT * FROM " + TABLE_USERS;
        Cursor cursor = db.rawQuery(query, null);

        User user = new User();

        if(cursor!=null)
        {
            user.setUserId(Integer.parseInt(cursor.getString(0)));
            user.setUserName(cursor.getString(1));
            user.setPassword(cursor.getString(2));
        }

        return user;

    }

}



    }



}

ここに私のログキャットがあります:

12-06 11:05:47.651: E/AndroidRuntime(634): FATAL EXCEPTION: main
12-06 11:05:47.651: E/AndroidRuntime(634): java.lang.RuntimeException: Unable to start activity ComponentInfo{testing.testapp/testing.testapp.Administrator}: java.lang.NullPointerException
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.app.ActivityThread.access$1500(ActivityThread.java:117)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.os.Handler.dispatchMessage(Handler.java:99)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.os.Looper.loop(Looper.java:123)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.app.ActivityThread.main(ActivityThread.java:3683)
12-06 11:05:47.651: E/AndroidRuntime(634):  at java.lang.reflect.Method.invokeNative(Native Method)
12-06 11:05:47.651: E/AndroidRuntime(634):  at java.lang.reflect.Method.invoke(Method.java:507)
12-06 11:05:47.651: E/AndroidRuntime(634):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
12-06 11:05:47.651: E/AndroidRuntime(634):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
12-06 11:05:47.651: E/AndroidRuntime(634):  at dalvik.system.NativeStart.main(Native Method)
12-06 11:05:47.651: E/AndroidRuntime(634): Caused by: java.lang.NullPointerException
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:291)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.widget.ListView.setAdapter(ListView.java:454)
12-06 11:05:47.651: E/AndroidRuntime(634):  at testing.testapp.Administrator.onCreate(Administrator.java:37)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-06 11:05:47.651: E/AndroidRuntime(634):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
12-06 11:05:47.651: E/AndroidRuntime(634):  ... 11 more
12-06 11:10:47.981: I/Process(634): Sending signal. PID: 634 SIG: 9
4

1 に答える 1

1

Administrator.java の 37 行目で NPE を取得しています。これは次のとおりです。

list.setAdapter(adapter);

レイアウトにfullname という名前の listView がありますかR.layout.administrator

usersList = h.getAllUsers();も確認してください。結果。

Log.d("size = ", usersList.size);
于 2012-12-06T06:36:15.737 に答える