Question

I am trying to sort a calculator app out in android. I have the layout set out fine and now I just need to do the code that will calculate. The app needs to show the number when it is pressed, then if say the + button is pressed it will store the first number, clear it off the screen, get a second number and then add them together. When the equal button is pressed it needs to show the results.

So far I have

public class Calculator extends Activity {

    public EditText display;  
    TextView screen;
    int a, result;
    int c;
    Button b1;
    int sum1, sum2;
    String r;

    public int getSum1(int sum1) {
        return sum1;
    }

    public int getSum2(int sum2) {
        return sum2;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);  

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public void buttonEventHandler(View v) {
        screen=(EditText)findViewById(R.id.screen);
        b1=(Button)findViewById(R.id.button1);
        switch(v.getId()) {

        case R.id.button1 :
            screen.setText(screen.getText() + "1");
            c = +1;
            break;

        case R.id.button2 : 
            screen.setText(screen.getText() + "2");
            c = +2;
            break;

        case R.id.button3 : 
            screen.setText(screen.getText() + "3");
            c = +3;
            break;

        case R.id.button4 : 
            screen.setText(screen.getText() + "4");
            c = +4;
            break;

        case R.id.button5 : 
            screen.setText(screen.getText() + "5");
            c = +5;
            break;

        case R.id.button6 : 
            screen.setText(screen.getText() + "6");
            c = +6;
            break;

        case R.id.button7 : 
            screen.setText(screen.getText() + "7");
            c = +7;
            break;

        case R.id.button8 : 
            screen.setText(screen.getText() + "8");
            c = +8;
            break;

        case R.id.button9 : 
            screen.setText(screen.getText() + "9");
            c = +9;
            break;

        case R.id.button0 : 
            screen.setText(screen.getText() + "0");
            c = +0;
            break;

        case R.id.buttonC :
            screen.setText(screen.getText() + "");
            c = 0;
            break;

        case R.id.buttonPlus :          


        case R.id.buttonEquals :



        }


    }
}

How to do calculations?

Answer 1

Set your sum1 to zero in onCreate. When the user taps +, do:

1. Add c to sum1
2. Display sum1
3. Reset c to zero so a new number can be typed

When the user taps =, do:

1. Add c to sum1
2. Display sum1
3. Reset c and sum1 to zero

This allows you to tap 4 + 5 + 6 = and see 15, for example.