Question

作为标题我想在Fragment中创建一个带有自定义行的列表视图。我的代码如下。

下面是我的片段类，它已扩展到listfragment，我对如何为此列表视图设置适配器感到困惑，我的代码如下所示。

    Fragment class    

public class CatFragActivity extends ListFragment {
private QuoteHelper dbQuoteHelper = null;
private Cursor ourcursor = null;
private QuoteAdapter adapter = null;
public int a = 0;

public CatFragActivity(){

}
 public View onCreateView(LayoutInflater inflater,
        @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {


     View rootview = inflater.inflate(R.layout.cat_frag, container, false);
    return rootview;


    ListView mylistview  = (ListView)getActivity().findViewById(R.id.CatList);
    dbQuoteHelper = new QuoteHelper(this);
    dbQuoteHelper.createDatabase();
    dbQuoteHelper.openDataBase();

    ourcursor = dbQuoteHelper.getcursor(a);
    startManagingCursor(ourcursor);
    adapter = new QuoteAdapter(ourcursor);

    mylistview.setAdapter(adapter);


}



    class QuoteAdapter extends CursorAdapter{
        QuoteAdapter(Cursor c){
            super(CatFragActivity.this,c);
        }

        @Override
        public void bindView(View row, Context ctxt, Cursor c) {
            QuoteHolder holder = (QuoteHolder)row.getTag();
            holder.populateFrom(c,dbQuoteHelper);
        }

        @Override
        public View newView(Context ctxt, Cursor c, ViewGroup parent) {
            LayoutInflater inflater = getLayoutInflater();
            View row =  inflater.inflate(R.layout.row, parent, false);
            QuoteHolder holder = new QuoteHolder(row);
            row.setTag(holder);
            return(row);
        }


}

     static class QuoteHolder{
            private TextView name = null;

            QuoteHolder(View row){
                name=(TextView)row.findViewById(R.id.quoteText);
            }
            void populateFrom(Cursor c, QuoteHelper r){
                name.setText(r.getName(c));
            }
        }


}

DatabaseHelper类

public class QuoteHelper extends SQLiteOpenHelper{
private static final String DATABASE_PATH="/data/data/com.my.quote/databases/";
private static final String DATABASE_NAME="store.db";
private static final int SCHEMA_VERSION=1;
private static final String TABLE_NAME="quotes";
private static final String TABLE_NAME_CAT="categories";
private static final String COLUMN_ID="_id";
private static final String COLUMN_TITLE="body";
private static final String COLUMN_CAT="name";
public static int i;
//private static final String COLUMN_CAT="4";

public SQLiteDatabase dbsqlite;
private final Context mycontext;

public QuoteHelper(Context context) {
    super(context,DATABASE_NAME,null,SCHEMA_VERSION );
    this.mycontext=context;
    // TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub

}

public void createDatabase(){
    createDB();
}

private void createDB(){
    boolean dbExist = DBExists();
    if(!dbExist){
        this.getReadableDatabase();
        copyDBFromResources();
    }
}


private boolean DBExists() {
    SQLiteDatabase db = null;

    try{
        String databasePath = DATABASE_PATH + DATABASE_NAME;
        db = SQLiteDatabase.openDatabase(databasePath, null, 
                SQLiteDatabase.OPEN_READWRITE);
        db.setLocale(Locale.getDefault());
        db.setLockingEnabled(true);
        db.setVersion(1);
    }catch(SQLiteException e){
        Log.e("SqlHelper","database not found");
    }

    if(db != null){
        db.close();
    }
    return db != null ? true : false;
}

private void copyDBFromResources() {
    InputStream inputStream = null;
    OutputStream outputStream = null;
    String dbFilePath = DATABASE_PATH + DATABASE_NAME;

    try{

        inputStream = mycontext.getAssets().open(DATABASE_NAME);

        outputStream = new FileOutputStream(dbFilePath);

        byte[] buffer = new byte[1024];
        int length;
        while((length = inputStream.read(buffer))> 0){

            outputStream.write(buffer,0,length);

        }

        outputStream.flush();
        outputStream.close();
        inputStream.close();

    }catch(IOException e){
        throw new Error("problem copying databse");

    }

}

public void openDataBase() throws SQLException{
    String mypath = DATABASE_PATH+DATABASE_NAME;
    dbsqlite = SQLiteDatabase.openDatabase(mypath, null,
            SQLiteDatabase.OPEN_READWRITE);
}

@Override
public synchronized void close(){
    if(dbsqlite != null){
        dbsqlite.close();

    }
    super.close();
}


public Cursor getcursor(int a){

    if(a==0){


        SQLiteQueryBuilder querybuilder = new SQLiteQueryBuilder();
        querybuilder.setTables(TABLE_NAME_CAT);

        String[] asCloumsToReturn = new String[] {COLUMN_ID,COLUMN_CAT};


        Cursor mcursor = querybuilder.query(dbsqlite, asCloumsToReturn, null, null, null, null, null);
        return mcursor;


            }
    else{

        int i = a;
        SQLiteQueryBuilder querybuilder = new SQLiteQueryBuilder();
        querybuilder.setTables(TABLE_NAME);

        String[] asCloumsToReturn = new String[] {COLUMN_ID,COLUMN_TITLE};
        String column ="category_id ="+ i;


        Cursor mcursor = querybuilder.query(dbsqlite, asCloumsToReturn, column, null, null, null, null);
        return mcursor;



    }

}

public String getName(Cursor c){
    return(c.getString(1));
}

  public Cursor getDetailByTerm(String id) {
        String[] args={id};

        return(getReadableDatabase()
                .rawQuery("SELECT _id, body FROM quotes WHERE _id=?",
                        args));
    }

  public Cursor getDetailsByCategory(String id){
      String[] args={id};
      return(getReadableDatabase()
              .rawQuery("SELECT _id, body from quotes WHERE category_id = ?", args)
              );

  }


}

Answer 1

只需在return rootView之前移动所有代码。

  ListView mylistview  = (ListView)rootView.findViewById(R.id.CatList);
  dbQuoteHelper = new QuoteHelper(getActivity());
  dbQuoteHelper.createDatabase();
  dbQuoteHelper.openDataBase();

  ourcursor = dbQuoteHelper.getcursor(a);
  startManagingCursor(ourcursor);
  adapter = new QuoteAdapter(ourcursor);

  mylistview.setAdapter(adapter);

最后它将是

  public View onCreateView(LayoutInflater inflater,
    @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {


    View rootview = inflater.inflate(R.layout.cat_frag, container, false);

    ListView mylistview  = (ListView)rootview .findViewById(R.id.CatList);
    dbQuoteHelper = new QuoteHelper(getActivity());
    dbQuoteHelper.createDatabase();
    dbQuoteHelper.openDataBase();

    ourcursor = dbQuoteHelper.getcursor(a);
    startManagingCursor(ourcursor);
    adapter = new QuoteAdapter(ourcursor);

    mylistview.setAdapter(adapter);

    return rootview;
 }

Answer 2

你onCreate永远不会执行到最后

 public View onCreateView(LayoutInflater inflater,
    @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {


View rootview = inflater.inflate(R.layout.cat_frag, container, false);
return rootview; //code STOPS here move this at the end of your onCreate

在片段android中创建自定义列表视图

2 个答案: