在对话框android中显示sqlite数据

Question

这是我的databasehandler文件     包com.example.saranshagarwal.studentdetailsapp;

public class MyDBHandler extends SQLiteOpenHelper {
public static final int DATABASE_VERSION = 1;
public static final String DATABASE_NAME = "mydetails.db";
public static final String TABLE_MYDETAIL = "mydetails";
public static final String COLUMN_NAME = "_name";
public static final String COLUMN_ROLLNUMBER = "_rollNumber";
public static final String COLUMN_MARKS = "_marks";
public static final String COLUMN_ID = "_id";

public MyDBHandler(Context context, String name, SQLiteDatabase.CursorFactory cursorFactory, int version) {
    super(context, DATABASE_NAME, cursorFactory, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
    String query = "CREATE TABLE " + TABLE_MYDETAIL + "(" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COLUMN_ROLLNUMBER + " INTEGER, " + COLUMN_NAME + " TEXT, " + COLUMN_MARKS + " INTEGER" + ");";
    Log.d("query", query);
    db.execSQL(query);

}

public void addMyDetail(MyDetails myDetails) {
    ContentValues values = new ContentValues();
    values.put(COLUMN_ROLLNUMBER, myDetails.get_rollNumber());
    values.put(COLUMN_NAME, myDetails.get_name());
    values.put(COLUMN_MARKS, myDetails.get_marks());
    SQLiteDatabase db = getReadableDatabase();
    long id = db.insert(TABLE_MYDETAIL, null, values);
    Log.d("id", "addMyDetail: " + id);
    db.close();
}

public void deleteMyDetail(String myName) {
    SQLiteDatabase db = getReadableDatabase();
    db.execSQL("DELETE FROM " + TABLE_MYDETAIL + " WHERE " + COLUMN_NAME + "=\"" + myName + "\";");
}

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

public String databaseToString() {
    String dbString = "";
    SQLiteDatabase db = getWritableDatabase();
    String query = "SELECT * FROM " + TABLE_MYDETAIL;
    Cursor c = db.rawQuery(query, null);
    c.moveToFirst();
    while (!c.isAfterLast()) {
        if (c.getString(c.getColumnIndex("_marks")) != null) {
            dbString += c.getString(c.getColumnIndex(COLUMN_ROLLNUMBER));
            dbString += c.getString(c.getColumnIndex(COLUMN_NAME));
            dbString += c.getString(c.getColumnIndex(COLUMN_MARKS));
            dbString += "\n";
        }
        c.moveToNext();
    }
    c.close();
    db.close();
    return dbString;
}
}

这是我的主要活动     公共类MainActivity扩展AppCompatActivity {     EditText名称，rollnumber，marks;     MyDBHandler myDBHandler;     TextView tv2;     最终的Context context = this;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    name = (EditText) findViewById(R.id.editText2);
    rollnumber = (EditText) findViewById(R.id.editText5);
    marks = (EditText) findViewById(R.id.editText4);
    tv2 = (TextView) findViewById(R.id.textView5);
    myDBHandler = new MyDBHandler(this, null, null, 1);

}

public void addButtonClicked(View view) {
    MyDetails myDetails = new MyDetails();
    myDetails.set_rollNumber(rollnumber.getText().toString());

    myDetails.set_name(name.getText().toString());
    myDetails.set_marks(marks.getText().toString());
    myDBHandler.addMyDetail(myDetails);
    String dbString = myDBHandler.databaseToString();
    tv2.setText(dbString);
    /*name.setText("");
    rollnumber.setText("");
    marks.setText("");*/
}

public void deleteButtonClicked(View view) {
    String inputText = name.getText().toString();
    myDBHandler.deleteMyDetail(inputText);

}

public void onViewClicked(View view) {
    Dialog dialog = new Dialog(context);
    dialog.setContentView(R.layout.popup_on_view);
    TextView tv1 = (TextView) findViewById(R.id.popup_text);
    String dbString = myDBHandler.databaseToString();

    dialog.show();
    tv1.setText(dbString);
}

}

这是日志文件

log

这是该应用的屏幕截图。当我点击查看按钮时，应用程序崩溃请帮忙 App

1：

1：

Answer 1

public void onViewClicked(View view) {
    Dialog dialog = new Dialog(context);
    dialog.setContentView(R.layout.popup_on_view);

// TextView tv1 =（TextView）findViewById（R.id.popup_text）;

// use this
       TextView tv1 = (TextView) view.findViewById(R.id.popup_text);

    String dbString = myDBHandler.databaseToString();

    dialog.show();
    tv1.setText(dbString);
}