public void convert() {
    EditText salaryAmountEditText = (EditText) findViewById(R.id.salaryAmountEditText);
    double salaryAmount = Double.parseDouble(salaryAmountEditText.toString());
    TextView textView = (TextView) findViewById(R.id.textView);
    tax tax1 = new tax(salaryAmount);
    Double pocketAmount = salaryAmount - tax1 ;

}