Question

我是初学者，我正在尝试开发简单的Android应用程序，但我需要一些帮助。我有一些按钮，标签等主要活动。按下一个按钮后，我启动第二个活动<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/1.7.9/fabric.min.js"></script> <p draggable="true" id="text">Drag me into the canvas!</p> <canvas id="canvas" width="200" height="200" ondrop="onDrop(event)" ondragover="onDragOver(event)"></canvas>，这是我需要帮助的地方。

SearchActivity.java

SearchActivity

DatabaseHelper.java

public class SearchActivity extends AppCompatActivity {  

      ListView lv;
        SearchView sv;
         ArrayAdapter<String> adapter;
        private ArrayList<String> items = getResults();

        private ArrayList<String> getResults(){
            DatabaseHelper db = new DatabaseHelper(this);
            db.openDatabase();
            ArrayList<String> resultList = new ArrayList<String>();
            Cursor c = db.query(tablename,column names,null,null,null,null,null);
            c.close();
            db.close();
            return  resultList;
        }

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_search);
            lv = (ListView)findViewById(R.id.listview);
            sv = (SearchView)findViewById(R.id.search);
            adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,items);
            lv.setAdapter(adapter);
            sv.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
                @Override
                public boolean onQueryTextSubmit(String query) {
                    return false;
                }

                @Override
                public boolean onQueryTextChange(String newText) {
                    adapter.getFilter().filter(newText);
                    return false;
                }
            });


        }
}

activity_search.xml只包含一个public class DatabaseHelper extends SQLiteOpenHelper { String DB_PATH = null; private static String DB_NAME = "dat"; private SQLiteDatabase myDatabase; private final Context myContext; public DatabaseHelper(Context context){ super(context, DB_NAME, null, 10); this.myContext = context; this.DB_PATH = "/data/data" + context.getPackageName() + "/" + "databases/"; Log.e("Path 1", DB_PATH); } public void createDatabase() throws IOException { boolean dbExist = checkDatabase(); if (dbExist) { } else { this.getReadableDatabase(); try { copyDatabse(); } catch (IOException e){ throw new Error("Error copying database"); } } } private boolean checkDatabase() { SQLiteDatabase checkDB = null; try { String myPath = DB_PATH + DB_NAME; checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } catch (SQLiteException e){ } if(checkDB != null){ checkDB.close(); } return checkDB != null ? true : false; } private void copyDatabse() throws IOException { InputStream myInput = myContext.getAssets().open(DB_NAME); String outFileName = DB_PATH + DB_NAME; OutputStream myOutput = new FileOutputStream(outFileName); byte[] buffer = new byte[10]; int length; while((length = myInput.read(buffer)) > 0){ myOutput.write(buffer, 0, length); } myOutput.flush(); myOutput.close(); myInput.close(); } public void openDatabase() throws SQLiteException { String myPath = DB_PATH + DB_NAME; myDatabase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); } @Override public synchronized void close(){ if(myDatabase != null) myDatabase.close(); super.close(); } @Override public void onCreate(SQLiteDatabase db) { } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { if(newVersion > oldVersion){ try{ copyDatabse(); } catch (IOException e){ e.printStackTrace(); } } } public Cursor query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) { return myDatabase.query(table,columns,null,null,null,null,null); } }和一个SearchView。

我在这里尝试的是从数据库加载表数据并能够使用ListView从中搜索并在SearchView中显示结果，只有字符串数组可用，但是这样做，整个TextView导致应用程序崩溃。

以下是我的错误：

SearchActivity

感谢您的回复。

使用数据库进行搜索

0 个答案: