Question

您好我是stackoverflow和java的新手。有人可以帮助解决我在listview中显示数据时遇到的问题。 ListView显示如下记录：com.example.ayeshanaeem.addviewdata.Record@72d730 以下是代码：ViewListContents.java

public class ViewListContents extends AppCompatActivity {
DatabaseHelper myDB;
private ClipData myClip;

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


    final ListView listView = (ListView)findViewById(R.id.listView);


    myDB = new DatabaseHelper(this);
    final ArrayList<Record> theList = new ArrayList<>();
    Cursor data = myDB.getAllData();
    if(data.getCount() == 0){
        Toast.makeText(ViewListContents.this, "The Database was empty", Toast.LENGTH_LONG).show();
    }
    else{
        while(data.moveToNext()){
            Record r=new Record();
            r.setRecordRollno(data.getString(1));
            r.setRecordName(data.getString(2));
            theList.add(r);
            ListAdapter listAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, theList);
            listView.setAdapter(listAdapter);
        }
    }
    //To copy text of item on click in listview
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
            ClipboardManager clipboard = (ClipboardManager) getSystemService(CLIPBOARD_SERVICE);
            String getstring = theList.get(i).toString();
            myClip = ClipData.newPlainText("text",getstring);
            clipboard.setPrimaryClip(myClip);
            Toast.makeText(getApplicationContext(),"Text copied", Toast.LENGTH_LONG).show();

        }
    });
}
}

我也制作了Record.java + RecordAdapter.java + MainActivity.java 这是DatabaseHelper.java

public DatabaseHelper(Context context) {
    super(context, DATABASE_NAME, null, 1);
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL("create table " + TABLE_NAME +" (ID INTEGER PRIMARY KEY AUTOINCREMENT, RollNo TEXT, NAME TEXT)");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
    onCreate(db);
}

public boolean insertData(String rollno,String name) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(COL_2,rollno);
    contentValues.put(COL_3,name);
    long result = db.insert(TABLE_NAME,null ,contentValues);
    if(result == -1)
        return false;
    else
        return true;
}

public Cursor getAllData() {
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor res = db.rawQuery("select * from "+TABLE_NAME,null);
    return res;
}

}

Answer 1

使用视图图案并创建自定义视图以绘制列表视图的每一行。

https://www.javacodegeeks.com/2013/09/android-viewholder-pattern-example.html

此外，您应该将Realm用于替代数据库，以通过对象管理您的信息。

https://realm.io/docs/java/latest

使用Base Adapter从Custom ListView中的数据库中获取数据

1 个答案: