1. 홈
  2. 질의 응답
  3. RecyclerView의 SQLite에서 데이터를 다시 얻으십시오

RecyclerView의 SQLite에서 데이터를 다시 얻으십시오

2015-02-02 3 views
0

recyclerView를 통해 SQLite에서 단편에 데이터를 표시하는 데 문제가 있습니다. 내가 showfragment 버튼을 클릭하면이 충돌하고 보여 .IT 6 개 자바 클래스와 4 XML 내가 Information.java DbHelperAdapter.java RecyclerView의 SQLite에서 데이터를 다시 얻으십시오

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 

import java.sql.SQLException; 
import java.util.ArrayList; 
import java.util.List; 

public class DbHelperAdapter{ 

DbHelper helper; 
public DbHelperAdapter(Context context){ 
    helper=new DbHelper(context); 
} 

public long insetData(String name,String password){ 
    SQLiteDatabase db=helper.getWritableDatabase(); 
    ContentValues contentValues=new ContentValues(); 
    contentValues.put(DbHelper.NAME,name); 
    contentValues.put(DbHelper.PASSWORD,password); 
    long id=db.insert(DbHelper.TABLE_NAME,null,contentValues); 
    db.close(); 
    return id; 
} 
public String getAllData(){ 
    SQLiteDatabase db= helper.getWritableDatabase(); 
    String[] columns={DbHelper.UID,DbHelper.NAME,DbHelper.PASSWORD}; 
    Cursor cursor=db.query(DbHelper.TABLE_NAME, columns, null, null, null, null, null); 
    StringBuffer buffer = new StringBuffer(); 
    while (cursor.moveToNext()){ 
     int cid=cursor.getInt(cursor.getColumnIndex(DbHelper.UID)); 
     String name = cursor.getString(cursor.getColumnIndex(DbHelper.NAME)); 
     String pass = cursor.getString(cursor.getColumnIndex(DbHelper.PASSWORD)); 
     buffer.append(cid+" "+name+" "+pass+"\n"); 

    } 
    return buffer.toString(); 
} 

public List<Information> getAllData_a(){ 
    SQLiteDatabase db= helper.getWritableDatabase(); 
    String[] columns={DbHelper.UID,DbHelper.NAME,DbHelper.PASSWORD}; 
    Cursor cursor=db.query(DbHelper.TABLE_NAME, columns, null, null, null, null, null); 
    List<Information> data=new ArrayList<>(); 

    while (cursor.moveToNext()){ 
     int cid=cursor.getInt(cursor.getColumnIndex(DbHelper.UID)); 
     String name = cursor.getString(cursor.getColumnIndex(DbHelper.NAME)); 
     String pass = cursor.getString(cursor.getColumnIndex(DbHelper.PASSWORD)); 
     Information current = new Information(); 
     current.u_id=cid; 
     current.user=name; 
     current.pass=pass; 
     data.add(current); 
    } 
    return data; 

} 

public String getData(String name){ 
    SQLiteDatabase db= helper.getWritableDatabase(); 
    String[] columns={DbHelper.NAME,DbHelper.PASSWORD}; 
    Cursor cursor=db.query(DbHelper.TABLE_NAME, columns, DbHelper.NAME+" = '"+name+"' ", null, null, null, null); 
    StringBuffer buffer = new StringBuffer(); 
    while (cursor.moveToNext()){ 
     String PersonName = cursor.getString(cursor.getColumnIndex(DbHelper.NAME)); 
     String pass = cursor.getString(cursor.getColumnIndex(DbHelper.PASSWORD)); 
     buffer.append(PersonName+" "+pass+"\n"); 
    } 
    return buffer.toString(); 
} 

static class DbHelper extends SQLiteOpenHelper { 
    private static final String DATABASE_NAME = "demo"; 
    private static final String TABLE_NAME = "tbl_demo"; 
    private static final int VERSION_NAME=3; 
    private static final String UID="_id"; 
    private static final String NAME="name"; 
    private static final String PASSWORD="Password"; 
    private static final String CREATE_TABLE="CREATE TABLE "+TABLE_NAME+" ("+UID+" INTEGER PRIMARY KEY AUTOINCREMENT, "+NAME+" VARCHAR(255),"+PASSWORD+" VARCHAR(255));"; 
    private static final String DROP_TABLE="DROP TABLE IF EXISTS "+TABLE_NAME+""; 
    private Context context; 

    public DbHelper(Context context){ 
     super(context,DATABASE_NAME,null,VERSION_NAME); 
     this.context=context; 
     Message.message(context, "constructorCalled"); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     try { 
      db.execSQL(CREATE_TABLE); 
      Message.message(context, "onCreateCalled"); 
     }catch (android.database.SQLException e){ 
      Message.message(context, ""+e); 
     } 

    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     try { 
      Message.message(context, "onUpgradeCalled"); 
      db.execSQL(DROP_TABLE); 
      onCreate(db); 
     } catch (android.database.SQLException e) { 
      Message.message(context, ""+e); 
     } 
    } 
} 
}

아래에 내 코드를주는거야있다 "불행하게도 앱이 들렸다" 
public class Information { 
int u_id; 
String user; 
String pass;}

MainActivity.java

import android.app.FragmentManager; 
import android.app.FragmentTransaction; 
import android.content.Intent; 
import android.database.sqlite.SQLiteDatabase; 
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.EditText; 
import android.support.v4.app.Fragment; 


public class MainActivity extends ActionBarActivity { 

DbHelperAdapter dbHelperAdapter; 
EditText userName; 
EditText password; 
EditText selectionName; 



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

    dbHelperAdapter = new DbHelperAdapter(this); 

    userName= (EditText) findViewById(R.id.username); 
    password= (EditText) findViewById(R.id.password); 
    selectionName= (EditText) findViewById(R.id.selection_name); 
} 

public void addUser(View view){ 
    String user = userName.getText().toString(); 
    String pass = password.getText().toString(); 
    long id = dbHelperAdapter.insetData(user,pass); 
    if(id<0){ 
     Message.message(this,"Unsuccessful"); 
    } 
    else { 
     Message.message(this,"Successfully insert A Row"); 
    } 
} 

public void getTheFragment(View view){ 
    Intent i= new Intent(this,MainActivity2.class); 
    startActivity(i); 
} 

public void viewDetails(View view){ 
    String data=dbHelperAdapter.getAllData(); 
    Message.message(this,data); 
} 
public void getDataBySelection(View view){ 
    String name = selectionName.getText().toString(); 
    String selections=dbHelperAdapter.getData(name); 
    Message.message(this,selections); 
} 

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

    return super.onOptionsItemSelected(item); 
}}

MainActivity2. 자바

import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 
import android.support.v4.app.FragmentPagerAdapter; 
import android.support.v4.view.ViewPager; 
import android.support.v7.app.ActionBarActivity; 
import android.os.Bundle; 


public class MainActivity2 extends ActionBarActivity { 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main_activity2); 

    ViewPager pager = (ViewPager) findViewById(R.id.viewPager); 
    pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager())); 
} 

private class MyPagerAdapter extends FragmentPagerAdapter { 

    public MyPagerAdapter(FragmentManager fm) { 
     super(fm); 
    } 

    @Override 
    public Fragment getItem(int pos) { 
     return new MyFragment(); 
    } 

    @Override 
    public int getCount() { 
     return 1; 
    } 
}}

Myfragment.java

import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 

public class MyFragment extends Fragment { 

RecyclerView recyclerView; 
RecyclerViewAdapter adapter; 
DbHelperAdapter dbHelperAdapter; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    // Inflate the layout for this fragment 
    View layout=inflater.inflate(R.layout.fragment_new, container, false); 
    recyclerView = (RecyclerView) layout.findViewById(R.id.list); 
    adapter = new RecyclerViewAdapter(getActivity(),dbHelperAdapter.getAllData_a()); 
    recyclerView.setAdapter(adapter); 
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); 
    return layout; 
}}

RecyclerViewAdapter.java

import android.content.Context; 
import android.support.v7.widget.RecyclerView; 
import android.text.Layout; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 

import java.util.Collections; 
import java.util.List; 

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> { 

private LayoutInflater inflater; 
List<Information> data= Collections.emptyList(); 

public RecyclerViewAdapter(Context context, List<Information> data){ 
    inflater = LayoutInflater.from(context); 
    this.data =data; 
} 

@Override 
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View view=inflater.inflate(R.layout.custom_raw,parent,false); 
    MyViewHolder holder=new MyViewHolder(view); 
    return holder; 
} 

@Override 
public void onBindViewHolder(MyViewHolder holder, int position) { 
    Information current = data.get(position); 
    holder.UID.setText(current.u_id); 
    holder.USER.setText(current.user); 
    holder.PASS.setText(current.pass); 
} 

@Override 
public int getItemCount() { 
    return data.size(); 
} 

class MyViewHolder extends RecyclerView.ViewHolder { 

    TextView UID; 
    TextView USER; 
    TextView PASS; 

    public MyViewHolder(View itemView) { 
     super(itemView); 
     UID= (TextView) itemView.findViewById(R.id.u_id); 
     USER = (TextView) itemView.findViewById(R.id.user); 
     PASS = (TextView) itemView.findViewById(R.id.pass); 
    } 
}}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context=".MainActivity" 
    android:orientation="vertical"> 
<EditText 
    android:id="@+id/username" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    /> 

<EditText 
    android:id="@+id/password" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_below="@+id/editText" 
    /> 

<Button 
    android:id="@+id/button" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_below="@+id/editText2" 
    android:onClick="addUser" 
    android:text="@string/add_user" /> 

<Button 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:onClick="viewDetails" 
    android:text="View Details" 
    android:id="@+id/view_details_btn" 
    android:layout_gravity="center_horizontal" /> 

<EditText 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/selection_name" 
    android:layout_gravity="center_horizontal" /> 

<Button 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:text="GetSelectedData" 
    android:onClick="getDataBySelection" 
    android:id="@+id/getDataBySelection" /> 

<Button 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:text="Show Fragment" 
    android:onClick="getTheFragment" 
    android:id="@+id/show_fragment" 
    /> 

</LinearLayout>

activity_main_activity2.xml

,536,913,632 10 
<android.support.v4.view.ViewPager 
    xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    android:id="@+id/viewPager" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    />

custom_raw.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" android:layout_width="match_parent" 
    android:layout_height="match_parent"> 
    <TextView 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:id="@+id/u_id" 
     android:layout_gravity="center" 
     android:text="UID"/> 
    <TextView 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:id="@+id/user" 
     android:layout_gravity="center" 
     android:text="NAME"/> 
    <TextView 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:id="@+id/pass" 
     android:layout_gravity="center" 
     android:text="PASSWORD"/> 

</LinearLayout>

fagment_new.xml

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 

    <android.support.v7.widget.RecyclerView 
     android:id="@+id/list" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content"> 
    </android.support.v7.widget.RecyclerView> 

</RelativeLayout>

구글 드라이브 링크 : https://drive.google.com/folderview?id=0B0uBfXsWeMlgX0U5OE8tREhxQkk&usp=sharing

로그 캣 오류 :

02-02 22:15:27.455 10562-10562/com.maticoders.databasetest E/AndroidRuntime? FATAL EXCEPTION: main 
    java.lang.NullPointerException 
      at com.maticoders.databasetest.MyFragment.onCreateView(MyFragment.java:29) 
      at android.support.v4.app.Fragment.performCreateView(Fragment.java:1786) 
      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947) 
      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126) 
      at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739) 
      at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489) 
      at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:486) 
      at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141) 
      at android.support.v4.view.ViewPager.populate(ViewPager.java:1073) 
      at android.support.v4.view.ViewPager.populate(ViewPager.java:919) 
      at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1441) 
      at android.view.View.measure(View.java:15635) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
      at android.view.View.measure(View.java:15635) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919) 
      at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:453) 
      at android.view.View.measure(View.java:15635) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
      at android.view.View.measure(View.java:15635) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919) 
      at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1411) 
      at android.widget.LinearLayout.measureVertical(LinearLayout.java:698) 
      at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 
      at android.view.View.measure(View.java:15635) 
      at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4919) 
      at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 
      at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2200) 
      at android.view.View.measure(View.java:15635) 
      at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2165) 
      at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1249) 
      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1443) 
      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1139) 
      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4872) 
      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:776) 
      at android.view.Choreographer.doCallbacks(Choreographer.java:579) 
      at android.view.Choreographer.doFrame(Choreographer.java:548) 
      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:762) 
      at android.os.Handler.handleCallback(Handler.java:800) 
      at android.os.Handler.dispatchMessage(Handler.java:100) 
      at android.os.Looper.loop(Looper.java:194) 
      at android.app.ActivityThread.main(ActivityThread.java:5371) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:525) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) 
      at dalvik.system.NativeStart.main(Native Method)

출처

2015-02-02 Kausar Ahmed Pial

+0

너무 많은 정보하지만 –

+0

:-(어떤 스택 트레이스가 실제로 너무 많이 말하고 싶지만 내 RecylerViewAdapter 클래스 텍스트 뷰 의 정수를 통과 정보를 제공합니다. 이렇게하면 구체적이고 답답한 질문을하기보다는 코드를 디버깅하는 데 큰 도움이됩니다. 이 사이트의 주제에 대해 [최소, 완전하고 검증 가능한 예] (http://stackoverflow.com/help/mcve)로 압축해야합니다. – Aiken

+0

죄송 임 여기에 유래 의 새로운 내 일부 로그 캣 오류 : 15 : 02-02 (22) 27.455 10562-10562/com.maticoders.databasetest E/AndroidRuntime : 치명적인 예외 : 주요 java.lang.NullPointerException이 닷컴에서. maticoders.databasetest.MyFragment.onCreateView (MyFragment.java:29) android.support.v4.app.Fragment.performCreateView (Fragment.java:1786) #stefan –

답변

1

오류는 컨텍스트를 통과하지 못한 내 RecyclerViewAdapter 클래스 내가 있었다 여기

이 
import android.content.Context; 
import android.support.v7.widget.RecyclerView; 
import android.text.Layout; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 

import java.util.Collections; 
import java.util.List; 

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> { 

    private Context context; 
    private LayoutInflater inflater; 
    List<Information> data= Collections.emptyList(); 

    public RecyclerViewAdapter(Context context, List<Information> data){ 
     this.context=context; 
     inflater = LayoutInflater.from(context); 
     this.data =data; 
    } 

    @Override 
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
     View view=inflater.inflate(R.layout.custom_raw,parent,false); 
     MyViewHolder holder=new MyViewHolder(view); 
     return holder; 
    } 

    @Override 
    public void onBindViewHolder(MyViewHolder holder, int position) { 
     Information current = data.get(position); 
     holder.UID.setText(String.valueOf(current.u_id)); 
     holder.USER.setText(current.user); 
     holder.PASS.setText(current.pass); 
    } 

    @Override 
    public int getItemCount() { 
     return data.size(); 
    } 

    class MyViewHolder extends RecyclerView.ViewHolder { 

     TextView UID; 
     TextView USER; 
     TextView PASS; 

     public MyViewHolder(View itemView) { 
      super(itemView); 
      UID= (TextView) itemView.findViewById(R.id.u_id); 
      USER = (TextView) itemView.findViewById(R.id.user); 
      PASS = (TextView) itemView.findViewById(R.id.pass); 
     } 
    } 
}

출처

2015-02-04 20:40:08

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