Android Eclipse EditText崩溃

Question

I am trying to make Cumulative GPA application. It contains 7 editTexts and one textView . One of them is for the number of the courses and the others are for the courses GPA. When I use it as for 6 courses it works but when I use it as example for 3 courses that I have to keep 3 of them empty the application crash.

public class MainActivity extends Activity {

    EditText e1, e2, e3, e4, e5, e6, e7;
    TextView t1;
    Button b1, b2;
    double a=0;
    double b=0;
    double c=0;
    double d=0;
    double e=0;
    double f=0;
    double g=0;
    double h=0;


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

        e1=(EditText)findViewById(R.id.editText1);
        e2=(EditText)findViewById(R.id.editText2);
        e3=(EditText)findViewById(R.id.editText3);
        e4=(EditText)findViewById(R.id.editText4);
        e5=(EditText)findViewById(R.id.editText5);
        e6=(EditText)findViewById(R.id.editText6);
        e7=(EditText)findViewById(R.id.editText7);

        t1=(TextView)findViewById(R.id.textView3);
        b2=(Button)findViewById(R.id.button2);

        b2.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub

            a=Double.parseDouble(e1.getText().toString());
            b=Double.parseDouble(e2.getText().toString());
            c=Double.parseDouble(e3.getText().toString());
            d=Double.parseDouble(e4.getText().toString());
            e=Double.parseDouble(e5.getText().toString());
            f=Double.parseDouble(e6.getText().toString());
            g=Double.parseDouble(e7.getText().toString());



            h= ((a+b+c+d+e+f)/g);


            t1.setText(Double.toString(h));

I tried this code:

{
    if (g==3)
    e4.setText("0");
    e5.setText("0");
    e6.setText("0");
}

but the same thing happened. Notice : e7 = the number of the courses

Answer 1

when you are keeping any one of edittext is empty your code will crash for eg: If your editext e1 is empty follwing code wont work as getText().toString() dont have any data

a=Double.parseDouble(e1.getText().toString());

you have to do like

if(!e1.getText().toString().equals(""))
{
a=Double.parseDouble(e1.getText().toString());
}

as for all.....

Answer 2

Modify your getText lines like this:

String e1 = e1.getText().toString();
a= e1.equals("")?0:Double.parseDouble(e1);

That will prevent the NumberFormatException that you must be getting now.