Is Edittext With Hint AND Default Value Possible?

Question

I am creating a tip calculator app and I was wondering how I could allow my edittext (user enters bill amount) to still display the hint (hint says "Enter Bill Amount") but also internally have a default value of zero. The reason I would like to do this is because if they press the calculate tip buttons and there is no text inputted in the edittext the app force closes, and I think with a default value of zero that would solve my problems because it would just say tip $0.00. Alternatively if somebody could advise me on how to make a pop-up saying they need to enter a bill amount that would be even better!

Current Main Java:

    package com.rockdrummer.calculating.calculating;

    import android.app.Activity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.TextView;
    import java.text.NumberFormat;
    import java.util.Locale;


    public class MainScreen extends Activity {
        private static final NumberFormat currencyFormat= NumberFormat.getCurrencyInstance();

        Button ten, fifteen, twenty;
        TextView tip;
        EditText bill_amount;
        double a = 0;
        double b;
        double af = 0;
        double bf;
        double ac = 0;
        double bc;


@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_screen);
    initControls();
    Locale.setDefault(Locale.US);




}



protected void initControls() {
    ten = (Button) findViewById(R.id.bTen);
    fifteen = (Button) findViewById(R.id.bFifteen);
    twenty = (Button) findViewById(R.id.bTwenty);
    tip = (TextView) findViewById(R.id.tip);
    bill_amount = (EditText) findViewById(R.id.bill);






    ten.setOnClickListener(new Button.OnClickListener() {
        public void onClick(View ten) {


            try {
                calculate();
            } catch (IndexOutOfBoundsException e) {
                e.printStackTrace();
            }
        }
    });
    fifteen.setOnClickListener(new Button.OnClickListener() {
        public void onClick(View fifteen) {
            try {
                calculate_f();
            } catch (IndexOutOfBoundsException e) {
                e.printStackTrace();
            }
        }
    });
    twenty.setOnClickListener(new Button.OnClickListener() {
        public void onClick(View twenty) {
            try {
                calculate_t();
            } catch (IndexOutOfBoundsException e) {
                e.printStackTrace();
            }
        }
    });
}

private void calculate() {


    a = 0 + Double.parseDouble(bill_amount.getText().toString());

    b = 0 + (a * 0.1);
    tip.setText("You Should Tip " + currencyFormat.format(b));
}

private void calculate_f() {
    af = 0 + Double.parseDouble(bill_amount.getText().toString());
    bf = 0 + (af * 0.15);
    tip.setText("You Should Tip " + currencyFormat.format(bf));
}

private void calculate_t() {
    ac = 0 + Double.parseDouble(bill_amount.getText().toString());
    bc = 0 + (ac * 0.20);
    tip.setText("You Should Tip " + currencyFormat.format(bc));
}

}

Answer 1

Just check if the text is empty in your onClick/onCalculate method. If empty, use 0, ie:

public void onCalculate() {
    float input = 0.0;
    if (editText.getText().toString().equals("")) {
         //Text is empty do nothing
    } else {
         //parse your value
         input = Float.parseFloat(editText.getText().toString());
    }
}