pasword match test seems to work

Sda2/P/Register/src/main/java/de/hdm_stuttgart/mi/Register.java

@@ -91,6 +91,7 @@ public class Register extends CustomComponent implements View, ValidateGlobal {
 		mainLayout.addComponents(password1Field);
 		
 		password2Field.addValidator(new ValidateSecondIdenticalInput(password1Field));
+		password1Field.addValidator(new ValidateSecondIdenticalInput(password2Field));
 		mainLayout.addComponents(password2Field);
 
 		{// Preparing cancel/OK buttons

Sda2/P/Register/src/main/java/de/hdm_stuttgart/mi/tools/ValidateSecondIdenticalInput.java

 package de.hdm_stuttgart.mi.tools;
 
 import com.vaadin.data.Validator;
+import com.vaadin.ui.AbstractField;
 import com.vaadin.ui.Field;
 
 public class ValidateSecondIdenticalInput implements Validator {
@@ -15,8 +16,29 @@ public class ValidateSecondIdenticalInput implements Validator {
 	@Override
 	public void validate(Object value) throws InvalidValueException {
 		
-		if (! (value instanceof String) || ! value.equals(reference.getValue())){
-			throw new InvalidValueException("Passwords do not match");
+		if (null != value &&  ! (value instanceof String)) {
+			throw new InvalidValueException("Field is not of string type");
+		} else if (null != reference.getValue() &&  ! (reference.getValue() instanceof String)) {
+			throw new InvalidValueException("Comparison field is not of string type");
+		} else {
+			final String stringValue, referenceStringValue;
+			if (null == value) {
+				stringValue = "";
+			} else {
+				stringValue = ((String) value);
+			}
+			
+			if (null == reference.getValue()) {
+				referenceStringValue = "";
+			} else {
+				referenceStringValue = ((String) reference.getValue());
+			}
+			
+			if (!referenceStringValue.equals("") && ! stringValue.equals(referenceStringValue)) {
+				throw new InvalidValueException("Passwords do not match");
+			} else {
+				((AbstractField<?>)reference).setComponentError(null);
+			}
 		}
 	}
 }