Validation in Android

useful validation for android

Email:- 

1) // default validation funtionality

if (!Patterns.EMAIL_ADDRESS.matcher(edt_email.getText().toString()).matches()) {

}

2) First charactor dont allow to "."(dot) or " "space.

edt_email.addTextChangedListener(new TextWatcher() {
    @Override    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

    }

    @Override    public void onTextChanged(CharSequence s, int start, int before, int count) {

    }

    @Override    public void afterTextChanged(Editable s) {

        try {

            String inputChar = edt_email.getText().toString();

            if (edt_email.getText().length() == 1) {

                if (inputChar.equalsIgnoreCase(".") || inputChar.equalsIgnoreCase(" ")) {
                    edt_email.setText("");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
});

Mobile No.

1) First character allow only "+" sign.

edt_mobile.addTextChangedListener(new TextWatcher() {
    @Override    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

    }

    @Override    public void onTextChanged(CharSequence s, int start, int before, int count) {

    }

    @Override    public void afterTextChanged(Editable s) {

        try {

            String last = edt_mobile.getText().toString();
            String inputChar = last.substring(last.length() - 1);


            if (edt_mobile.getText().length() > 1) {

                if (inputChar.equalsIgnoreCase("+")) {
                    edt_mobile.setText(edt_mobile.getText().toString().substring(0, edt_mobile.getText().length() - 1));
                    edt_mobile.setSelection(edt_mobile.getText().length());
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

    }
});

2) Only allow particular digits (only allow declared digit or characters)

<string name="mobile_digits">+9876543210</string>

in xml

android:digits="@string/mobile_digits"