如果 SQLite 为空或有记录，则更改片段中的视图

Posted 2023-04-19

【中文标题】如果 SQLite 为空或有记录，则更改片段中的视图

【英文标题】：Change View in Fragment if SQLite it is null or has a record

【发布时间】：2019-05-26 15:00:02

【问题描述】：

我正在尝试更改我称之为历史的片段中的视图。 如果数据库 SQLite 有记录，我想显示列表视图，但如果有空显示另一个视图。 如果数据库已记录视图调用 history_item 作为布局和 historyName 显示 TextView 我想要如果数据库没有记录调用 fragment_history 那里有带有 ImageView 和 TextView 的 LinearLayout。

history_item.XML

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="horizontal"
    android:background="@drawable/selector_btn_home"
    android:id="@+id/historyLayout"
    android:layout_
    android:layout_>
    <ImageView android:id="@id/ivHistory" style="@style/ivHistory" />
    <TextView android:id="@+id/historyName" android:layout_ style="@style/TextViewQuery"/>
    <ImageView android:id="@+id/imgViewSetQuery" style="@style/ImageViewSetQuery" />
    <TextView android:textSize="@dimen/search_font" android:textColor="@android:color/white"
        android:gravity="center" android:id="@+id/btnDeleteHistory" android:background="@color/red" android:paddingLeft="5.0dip"
        android:paddingRight="5.0dip" android:visibility="gone" android:longClickable="false"
        android:layout_ android:layout_ android:text="@string/Delete" />
</LinearLayout>

FragmentHistory.class

public class FragmentHistory extends Fragment 
    View paramView;
   public  TextView textView, showDeleteButton, noSearch;
    LinearLayout test;
    public ImageView showHistoryQuery;

    DatabaseHelper mDatabaseHelper;

    private ListView mListView;
    private LinearLayout noQueries;
    public FragmentHistory() 
    

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) 
        paramView = inflater.inflate(R.layout.history, container, false);
        textView = paramView.findViewById(R.id.historyName);
        noSearch = paramView.findViewById(R.id.tvHistoryPage);
        mListView = paramView.findViewById(R.id.listView);
        noQueries = paramView.findViewById(R.id.linLayoutEmptyList);
        mDatabaseHelper = new DatabaseHelper(getActivity());
        populateListView();
        ((MainActivity)getActivity()).setFragmentRefreshListener(new MainActivity.FragmentRefreshListener() 
            @Override
            public void onRefresh() 
                FragmentTransaction ft = getFragmentManager().beginTransaction();
                ft.detach(FragmentHistory.this).attach(FragmentHistory.this).commit();
            
        );


        return paramView;
    

    private void populateListView() 


        //get the data and append to a list
        Cursor data = mDatabaseHelper.getData();
        ArrayList<String> listData = new ArrayList<>();
        while (data.moveToNext()) 
            listData.add(data.getString(1));
        
            ListAdapter adapter = new ArrayAdapter<String>(getActivity(), R.layout.history_item, R.id.historyName, listData);
            mListView.setAdapter(adapter);


     mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() 
         @Override
         public void onItemClick(AdapterView<?> parent, View view, int position, long id) 
             String name = parent.getItemAtPosition(position).toString();

             Cursor data = mDatabaseHelper.getItemID(name); //get the id associated with that name
             int itemID = -1;
             while(data.moveToNext())
                 itemID = data.getInt(0);
             
             if(itemID > -1)
                 Intent editScreenIntent = new Intent(getActivity(), ActivitySearchEngine.class);
                 editScreenIntent.putExtra("id",itemID);
                 editScreenIntent.putExtra("name",name);
                 startActivity(editScreenIntent);
             

         
     );

        mListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() 
            @Override
            public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) 
                String name = parent.getItemAtPosition(position).toString();
                Cursor data = mDatabaseHelper.getItemID(name); //get the id associated with that name
                int  itemID = -1;

                while(data.moveToNext())
                    itemID = data.getInt(0);
                
                if(itemID > -1)
                    showDeleteButton = view.findViewById(R.id.btnDeleteHistory);
                    showHistoryQuery =  view.findViewById(R.id.imgViewSetQuery);
                    showDeleteButton.setVisibility(View.VISIBLE);
                    showHistoryQuery.setVisibility(View.GONE);

                    final int finalItemID = itemID;
                    final String finalName = name;

                    showDeleteButton.setOnClickListener(new View.OnClickListener() 
                        @Override
                        public void onClick(View v) 
                            mDatabaseHelper.deleteName(finalItemID, finalName);
                            FragmentTransaction ft = getFragmentManager().beginTransaction();
                            ft.detach(FragmentHistory.this).attach(FragmentHistory.this).commit();
                        
                    );
                
                return true;
            
        );

    

fragment_history.XML

<LinearLayout android:orientation="vertical" android:layout_
    android:layout_
    xmlns:android="http://schemas.android.com/apk/res/android">
    <ListView android:id="@+id/lvHistory" android:longClickable="true"
        android:layout_ android:layout_
        android:listSelector="@android:color/transparent" android:soundEffectsEnabled="false"
        android:overScrollMode="never" />
    <LinearLayout android:gravity="center" android:orientation="vertical"
        android:id="@+id/linLayoutEmptyList" android:paddingBottom="32.0dip" android:visibility="gone"
        android:layout_ android:layout_>
        <ImageView android:layout_gravity="center" android:id="@+id/ivHistoryPage"
            android:layout_
            android:layout_
            android:layout_marginBottom="@dimen/history_query_empty_margin"
            android:src="@drawable/ic_history" />
        <TextView android:textSize="20.0sp" android:textColor="@color/blue_title"
            android:gravity="center" android:layout_gravity="center" android:id="@+id/tvHistoryPage"
            android:layout_ android:layout_
            android:text="@string/SVEmptyHistoryTableMessage" android:lineSpacingExtra="2.0sp" />
    </LinearLayout>
</LinearLayout>

数据库类

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

public class DatabaseHelper extends SQLiteOpenHelper 

    private static final String TABLE_NAME = "people_table";
    private static final String COL1 = "ID";
    private static final String COL2 = "name";

    public DatabaseHelper(Context context) 
        super(context, TABLE_NAME, null, 1);
    
    @Override
    public void onCreate(SQLiteDatabase db) 
        String createTable = "CREATE TABLE " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, " +
                COL2 +" TEXT)";
        db.execSQL(createTable);
    

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) 
        db.execSQL("DROP IF TABLE EXISTS " + TABLE_NAME);
        onCreate(db);
    
    public boolean addData(String item) 
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(COL2, item);
        long result = db.insert(TABLE_NAME, null, contentValues);

        //if date as inserted incorrectly it will return -1
        if (result == -1) 
            return false;
         else 
            return true;
        
    
    public Cursor getData()
        SQLiteDatabase db = this.getWritableDatabase();
        String query = "SELECT * FROM " + TABLE_NAME;
        Cursor data = db.rawQuery(query, null);
        return data;
    

    public Cursor getItemID(String name)
        SQLiteDatabase db = this.getWritableDatabase();
        String query = "SELECT " + COL1 + " FROM " + TABLE_NAME +
                " WHERE " + COL2 + " = '" + name + "'";
        Cursor data = db.rawQuery(query, null);
        return data;
    

    public void updateName(String newName, int id, String oldName)
        SQLiteDatabase db = this.getWritableDatabase();
        String query = "UPDATE " + TABLE_NAME + " SET " + COL2 +
                " = '" + newName + "' WHERE " + COL1 + " = '" + id + "'" +
                " AND " + COL2 + " = '" + oldName + "'";
        db.execSQL(query);
    
    public void deleteName(int id, String name)
        SQLiteDatabase db = this.getWritableDatabase();
        String query = "DELETE FROM " + TABLE_NAME + " WHERE "
                + COL1 + " = '" + id + "'" +
                " AND " + COL2 + " = '" + name + "'";
        db.execSQL(query);
    

【参考方案1】：

我能够解决这个问题，只是我在这些行中添加了这段代码，这就像魅力一样。

Cursor data = mDatabaseHelper.getData();
        ArrayList<String> listData = new ArrayList<>();
           while (data.moveToNext()) 
               listData.add(data.getString(1));
           
           if (data.getCount() != 0) 
           ListAdapter adapter = new ArrayAdapter<String>(getActivity(), R.layout.history_item, R.id.historyName, listData);
           mListView.setAdapter(adapter);
        else 
           mListView.setVisibility(View.GONE);
           noQueries.setVisibility(View.VISIBLE);