User Input

User interface contains two types of user input controls: TextInput, which accepts all characters and NumericInput, which accepts only digits.

Implement the class TextInput that contains:

• Public method void add(char c) - adds the given character to the current value
• Public method String getValue() - returns the current value

Implement the class NumericInput that:

• Inherits from TextInput
• Overrides the add method so that each non-numeric character is ignored

For example, the following code should output "10":

TextInput input = new NumericInput();
input.add('1');
input.add('a');
input.add('0');
System.out.println(input.getValue());