Question

整个项目最初使用的代码完全相同，我甚至将其恢复了一段时间，它没有显示＆＃34; android.database.CursorIndexOutOfBoundsException：请求索引0，大小为0＆＃34 ;.我很乐意寻求帮助来解决这个问题，因为我知道这很简单，因为它关于Cursor但我仍然无法解决这个问题。< / p>

相关守则如下：

DatabaseOperations.java 包m.rami.psucalculator;

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 DatabaseOperations extends SQLiteOpenHelper {
public static final int database_version = 3;
public String CREATE_QUERY = "CREATE TABLE 
"+TableData.TableInfo.TABLE_NAME+"("+TableData.TableInfo.USER_NAME+" 
TEXT,"+TableData.TableInfo.USER_PASSWORD+" TEXT );";

public DatabaseOperations(Context context) {
    super(context, TableData.TableInfo.DATABASE_NAME, null, 
database_version);
    Log.d("Database operations", "Database created");

    // constructor stub
}

@Override
public void onCreate(SQLiteDatabase sdb) {
    sdb.execSQL(CREATE_QUERY);
    Log.d("Database operations","Table created");



    // method stub
}

@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {



    // method stub
}

public void putInformation(DatabaseOperations dop, String name, String pass) 
{
    SQLiteDatabase SQ = dop.getWritableDatabase();
    ContentValues cv = new ContentValues();
    cv.put(TableData.TableInfo.USER_NAME, name);
    cv.put(TableData.TableInfo.USER_PASSWORD, pass);
    long k = SQ.insert(TableData.TableInfo.TABLE_NAME, null,cv);
    Log.d("Database operations", "One raw inserted");

    // inserts data into database


}

public Cursor getInformation(DatabaseOperations dop){
    SQLiteDatabase SQ = dop.getReadableDatabase();
    String[] columns = {TableData.TableInfo.USER_NAME, 
TableData.TableInfo.USER_PASSWORD};
    Cursor CR = SQ.query(TableData.TableInfo.TABLE_NAME ,columns, null, 
null, null, null, null);
    return CR;
}

}

Home.java

package m.rami.psucalculator;

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

import org.w3c.dom.Text;


public class Home extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

public static final String DEFAULT = "N/A";
TextView userNameTestView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) 
findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", 
Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, 
R.string.navigation_drawer_close);
    drawer.addDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) 
findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    //this code makes HOME the default fragment
    android.support.v4.app.FragmentTransaction 
ft=getSupportFragmentManager().beginTransaction();
    ft.replace(R.id.content_home,new HomeFrag());
    ft.commit();

    navigationView.setCheckedItem(R.id.nav_home);



    userNameTestView = findViewById(R.id.psuusername);
}


public void load(View view){
    SharedPreferences sharedPreferences = getSharedPreferences("user_info", 
Context.MODE_PRIVATE);
    String name = sharedPreferences.getString("name",DEFAULT);

    userNameTestView.setText(name);
}


public void setActionBarTitle(String title){
    getSupportActionBar().setTitle(title);
}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.home, 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();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        Toast.makeText(this,"SETTINGS",Toast.LENGTH_SHORT).show();
        Intent i = new Intent(Home.this,Settings.class);
        startActivity(i);
    } else if (id == R.id.action_information){
        Toast.makeText(this,"INFORMATION",Toast.LENGTH_SHORT).show();
        Intent i = new Intent(Home.this,Information.class);
        startActivity(i);
    }

    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_home) {
        Toast.makeText(this,"HOME", Toast.LENGTH_SHORT).show();
        android.support.v4.app.FragmentTransaction 
ft=getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.content_home,new HomeFrag());
        ft.commit();
    } else if (id == R.id.nav_math_250) {
        Toast.makeText(this,"MATH 250",Toast.LENGTH_SHORT).show();
        FragmentManager ft=getSupportFragmentManager();
        ft.beginTransaction().replace(R.id.content_home,new 
MATH250Frag()).commit();

    } else if (id == R.id.nav_cmpsc_475) {
        Toast.makeText(this,"CMPSC 475",Toast.LENGTH_SHORT).show();
        FragmentManager ft=getSupportFragmentManager();
        ft.beginTransaction().replace(R.id.content_home,new 
CMPSC475Frag()).commit();
    } else if (id == R.id.nav_stat_318) {
        Toast.makeText(this,"STAT 318",Toast.LENGTH_SHORT).show();
        FragmentManager ft=getSupportFragmentManager();
        ft.beginTransaction().replace(R.id.content_home,new 
STAT318Frag()).commit();
    } else if (id == R.id.nav_math_220) {
        Toast.makeText(this, "MATH 220",Toast.LENGTH_SHORT).show();
        FragmentManager ft=getSupportFragmentManager();
        ft.beginTransaction().replace(R.id.content_home,new 
MATH220Frag()).commit();
    } else if (id == R.id.nav_cmpsc_455){
        Toast.makeText(this,"CMPSC 455", Toast.LENGTH_SHORT).show();
        FragmentManager ft=getSupportFragmentManager();
        ft.beginTransaction().replace(R.id.content_home,new 
CMPSC455Frag()).commit();
    } else if(id == R.id.nav_cmpsc469){
        Toast.makeText(this,"CMPSC 469",Toast.LENGTH_SHORT).show();
        FragmentManager ft=getSupportFragmentManager();
        ft.beginTransaction().replace(R.id.content_home,new 
CMPSC469Frag()).commit();
    }
    /*
        use this code to make an activity without
        nav menu.
        ** CREATE example class and nav_example
        else if(id==R.id.nav_example){
        Intent i = new Intent(Home.this,example.class);
        startActivity(i);
        }
     */

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
}

login.java

package m.rami.psucalculator;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import static java.security.AccessController.getContext;

public class login extends Activity {
Button bLogin, bRegister;
EditText USERNAME, USERPASS;
String username, userpass;
Context context = this;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        //method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);
        bLogin = (Button) findViewById(R.id.loginbutton);
        USERNAME = (EditText) findViewById(R.id.user_name);
        USERPASS = (EditText) findViewById(R.id.user_pass);
        bRegister = findViewById(R.id.registernowbutton);
        bLogin.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                Bundle b = getIntent().getExtras();
                int status = b.getInt("status");
                if(status == 1)
                {
                    Toast.makeText(getBaseContext(), "Please Wait...", 
Toast.LENGTH_SHORT).show();
                    username = USERNAME.getText().toString();
                    userpass = USERPASS.getText().toString();
                    DatabaseOperations DOP = new 
DatabaseOperations(context);
                    Cursor CR = DOP.getInformation(DOP);
                    CR.moveToFirst();
                    boolean loginstatus = false;
                    String NAME = "";
                    do
                    {
                        if(username.equals(CR.getString(0))&& 
(userpass.equals(CR.getString(1))))
                        {
                            loginstatus = true;
                            NAME = CR.getString(0);
                        }

                    }while(CR.moveToNext());
                    if(loginstatus)
                    {
                        Toast.makeText(getBaseContext(), "Login Success\n 
Hello "+NAME, Toast.LENGTH_LONG).show();
                        finish();
                        Intent logintohome = new Intent(login.this, 
Home.class );
                        startActivity(logintohome);
                    }
                    else
                    {
                        Toast.makeText(getBaseContext(), "Login 
Unsuccessful", Toast.LENGTH_LONG).show();
                        finish();
                    }



                }
                else if(status == 2)
                {
                    Toast.makeText(getBaseContext(), "Please Wait...", 
Toast.LENGTH_SHORT).show();
                    username = USERNAME.getText().toString();
                    userpass = USERPASS.getText().toString();
                    DatabaseOperations DOP = new 
DatabaseOperations(context);
                    Cursor CR = DOP.getInformation(DOP);
                    CR.moveToFirst();
                    boolean loginstatus = false;
                    String NAME = "";
                    do
                    {
                        if(username.equals(CR.getString(0))&& 
(userpass.equals(CR.getString(1))))
                        {
                            loginstatus = true;
                            NAME = CR.getString(0);
                        }

                    }while(CR.moveToNext());
                    if(loginstatus)
                    {
                        Toast.makeText(getBaseContext(), "Login Success\n 
Hello "+NAME, Toast.LENGTH_LONG).show();

                        Intent i = new Intent("update_filter");
                        Bundle BN = new Bundle();
                        BN.putString("user_name",NAME );
                        BN.putString("user_pass",userpass );
                        i.putExtras(BN);
                        startActivity(i);
                        finish();
                        Intent logintohome = new Intent(login.this, 
Home.class );
                        startActivity(logintohome);
                    }
                    else
                    {
                        Toast.makeText(getBaseContext(), "Login Unsuccessful 
", Toast.LENGTH_LONG).show();
                        finish();
                    }






                }
                else if(status == 3)
                {
                    Toast.makeText(getBaseContext(), "Please Wait...", 
Toast.LENGTH_SHORT).show();
                    username = USERNAME.getText().toString();
                    userpass = USERPASS.getText().toString();
                    DatabaseOperations DOP = new 
DatabaseOperations(context);
                    Cursor CR = DOP.getInformation(DOP);
                    CR.moveToFirst();
                    boolean loginstatus = false;
                    String NAME = "";
                    do
                    {
                        if(username.equals(CR.getString(0))&& 
(userpass.equals(CR.getString(1))))
                        {
                            loginstatus = true;
                            NAME = CR.getString(0);
                        }

                    }while(CR.moveToNext());
                    if(loginstatus)
                    {
                        Toast.makeText(getBaseContext(), "Login Success\n 
Hello "+NAME, Toast.LENGTH_LONG).show();
                        Intent i = new Intent("delete_filter");
                        Bundle B = new Bundle();
                        B.putString("user_name",NAME );
                        i.putExtras(B);
                        startActivity(i);
                        finish();
                        Intent logintohome = new Intent(login.this, 
Home.class );
                        startActivity(logintohome);
                    }
                    else
                    {
                        Toast.makeText(getBaseContext(), "Login 
Unsuccessful", Toast.LENGTH_LONG).show();
                        finish();
                    }




                    //Intent i = new Intent("delete_filter");
                    //startActivity(i);
                }

            }
        });

        bRegister.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                Intent logintoregister = new 
Intent(login.this,RegisterUser.class);
                startActivity(logintoregister);

            }
        }


        );

    }

    public void save(View view){
        SharedPreferences sharedPreferences = 
getSharedPreferences("user_info",Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putString("name",USERNAME.getText().toString());
        DatabaseOperations DOOP = new DatabaseOperations(context);
        Cursor CR = DOOP.getInformation(DOOP);
        CR.moveToFirst();
        String NAMENAME = "";
        do {
            if(username.equals(CR.getString(0))){
                NAMENAME = CR.getString(0);
            }
        } while(CR.moveToNext());


        editor.commit();
    }

    public void next(View view){
        Intent i = new Intent(this, Home.class);
        startActivity(i);
    }

}

TableData.java

package m.rami.psucalculator;

import android.provider.BaseColumns;

public class TableData {
public TableData(){





}
public static abstract class TableInfo implements BaseColumns {
    public static final String USER_NAME = "user_name";
    public static final String USER_PASSWORD = "user_password";
    public static final String DATABASE_NAME = "user_info";
    public static final String TABLE_NAME = "reg_table";

}



}

错误屏幕

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: m.rami.psucalculator, PID: 28997
              android.database.CursorIndexOutOfBoundsException: Index 0 
requested, with a size of 0
                  at 
android.database.AbstractCursor.checkPosition(AbstractCursor.java:460)
                  at 
android.database.AbstractWindowedCursor.
checkPosition(AbstractWindowedCursor.java:136)
                  at 
android.database.AbstractWindowedCursor.
getString(AbstractWindowedCursor.java:50)
                  at m.rami.psucalculator.login$1.onClick(login.java:51)
                  at android.view.View.performClick(View.java:6256)
                  at android.view.View$PerformClick.run(View.java:24701)
                  at android.os.Handler.handleCallback(Handler.java:789)
                  at android.os.Handler.dispatchMessage(Handler.java:98)
                  at android.os.Looper.loop(Looper.java:164)
                  at 
android.app.ActivityThread.main(ActivityThread.java:6541)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at 
com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                  at 
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

Answer 1

反转你的do / while因为它会执行，即使条件最初是假的。

                while(CR.moveToNext()) {
                    if(username.equals(CR.getString(0))
                        && (userpass.equals(CR.getString(1))))  {
                        loginstatus = true;
                        NAME = CR.getString(0);
                    }

                }

或者更好：因为moveToFirst（）返回一个布尔值意味着要获取的数据，你可以检查它：

       if(CR.moveToFirst())
          while(CR.moveToNext()){
              //do thing with data

Answer 2

您的表创建代码存在一些问题。试试这组代码。

db.execSQL("CREATE TABLE IF NOT EXISTS " + purpose_of_loan_tb + " (" + pk_id + " INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "
                + purpose_of_loan_id + " INTEGER , " + user_id + " INTEGER, " + purpose_of_loan_status + " INTEGER, " +
                purpose_of_loan_json + " TEXT);");

插入代码：

public long insertRows(SQLiteDatabase db, String tableName, ContentValues contentValues) {
        long n = db.insert(tableName, null, contentValues);

        Util.printMessage(TAG, "Row inserted in " + tableName + " : " + n);
        return n;
    }

通过根据列名和相应值将值放入内容值键来调用此方法。

在你的情况下：

contentValues.put("TableData.TableInfo.USER_NAME","ABCD");

要检索所有数据，您可以使用此方法：

public Cursor getValueByColumn(SQLiteDatabase db, String table_name,
                                   String select_clause_colunms, String where_clause_column) {
        Cursor cursor = db
                .query(table_name, null, null, null, null, null, null);

        // print("Count " + cursor.getCount());

        return cursor;
    }

这将返回光标，您可以在其中检查光标计数。

android.database.CursorIndexOutOfBoundsException：请求索引0，大小为0但是之前的代码完全相同

2 个答案: