Bengali calculator Android studio

Question

I am trying to build a Bengali calculator. Here is the layout of English calculator :

By editing layout I can easily replace English digits with Bengali digits. But when it comes to the calculation i am unable to do it. Like i want it to calculate in Bengali too. e.g it will perform in Bengali like this (২+২=৪) instead of (2+2=4). I have tried the replacing method but it didn't work.

Bengali digits(০ ১ ২ ৩ ৪ ৫ ৬ ৭ ৮ ৯)
English digits(1 2 3 4 5 6 7 8 9)

Thank you for your time.

public class MainActivity extends AppCompatActivity {
    private TextView screen;
    private String str2, result, str, sign;
    private double a, b;
 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        screen = (TextView) findViewById(R.id.textview);
        str = "";
    }

    public void onclick(View v) {
        Button button = (Button) v;
        str += button.getText().toString();
        screen.setText(str);
        a = Double.parseDouble(str);
    }
    public void onclicksign(View v) {
        Button button = (Button) v;
        sign = button.getText().toString();
        screen.setText(sign);
        str = "";
    }
    public void calculate(View v) {
        Button button = (Button) v;

        str2 = screen.getText().toString();
        b = Double.parseDouble(str2);
        if (sign.equals("+")) {
            result = a + b + "";
        } else if (sign.equals("-")) {
            result = a - b + "";
        } else if (sign.equals("*")) {
            result = a * b + "";
        } else if (sign.equals("/")) {
            result = a / b + "";
        } else {
            screen.setText("?????? ???");
        }
        {
            screen.setText(result);

        }
    }
}

Answer 1

Your code tries to extract numerical values from the text on buttons.

You should write custom Double parser which parses Bengali number text to numerical value.

Also you should write a method which converts numerical double value to Bengali number text. You have to use this method while setting screen text.

public class MainActivity extends AppCompatActivity {
    private TextView screen;
    private String str2, result, str, sign;
    private double a, b;
 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        screen = (TextView) findViewById(R.id.textview);
        str = "";
    }

    public void onclick(View v) {
        Button button = (Button) v;
        str += button.getText().toString();
        screen.setText(str);
        a = BengaliUtils.toDouble(str);
    }
    public void onclicksign(View v) {
        Button button = (Button) v;
        sign = button.getText().toString();
        screen.setText(sign);
        str = "";
    }
    public void calculate(View v) {
        Button button = (Button) v;

        str2 = screen.getText().toString();
        b = BengaliUtils.toDouble(str2);
        if (sign.equals("+")) {
            result = a + b + "";
        } else if (sign.equals("-")) {
            result = a - b + "";
        } else if (sign.equals("*")) {
            result = a * b + "";
        } else if (sign.equals("/")) {
            result = a / b + "";
        } else {
            screen.setText("?????? ???");
        }
        {
            screen.setText(BengaliUtils.toString(result));

        }
    }
}

class BengaliUtils {
    static String toString(double value) {
        //TODO implement logic
        // You can convert value to regular number text, and then replace each char with the Bengali version. The performance could be improved with better logic.
        return text;
    }

    static double toDouble(String text) {
        //TODO implement logic
        //You can do that, first replace each Bengali char with normal number char. The use Double.parse on new text. The performance could be improved with better logic.
        return value;
    }
}

Answer 2

            @Override
            public void onClick(View view) {
                String num  = editText.getText().toString();
                //split the num

                char[] charArray = num.toCharArray();
                StringBuilder stringBuilder = new StringBuilder(charArray.length);

                // loop and convert using  switch case

                for (int i=0; i<charArray.length; i++ ){

                    char character = charArray[i];


                    switch (character){
                        case '.':
                            stringBuilder.append(".");
                            break;
                        case '0':
                            stringBuilder.append("০");
                            break;
                        case '1':
                            stringBuilder.append("১");
                            break;
                    }
                }
                //Final result..
                textView.setText(stringBuilder);

            }

Try above code...

Here is the output

---

NOTE

• I am taking English numbers from EditText on Button click. You will have to change that in your code.
• Currently, switch can handle 0,1,.(decimal) only. You can easily add cases for other numbers too.
• Please Check this answer too. Convert String to another locale in java