Manipulator.java

public class Manipulator {

public Manipulator(Class m){
        manipulate(m);
}

private void manipulate(Class m){
    PrintStream myStream = new PrintStream(System.out){
        @Override
        public void println(String mystr) {
            String[] str = mystr.split("\\s+");
            mystr = "";
            //here I override the default println method, split user's printable string into array of words then I set that string empty.
            String match = ""; //this will hold each match
            
            for(String s : str) {
                if(s.charAt(0) == '$' && s.charAt(1) == '{' && s.charAt(s.length()-1) == '}') {
                //here i search for ${object name} and I replace them with empty character.
                    match = s;
                    match = match.replace("$", "");
                    match = match.replace("{", "");
                    match = match.replace("}", "");
                    
                    if(match.length() > 0) {
                        try {
                            match = returnVal(match, m);
                        } catch (IllegalAccessException e) {
                            e.printStackTrace();
                        }
                        mystr += match + " ";
                    } else {
                    
                        mystr += s + " ";
                    }
                } else {
                    mystr += s + " ";
                }
            }
            super.println(mystr);
        }
    };
    System.setOut(myStream);
}

private String returnVal(String s, Class operator) {
    Field[] fields = operator.getDeclaredFields();
    //here I reach the objects I've created in the class that I passed to my Manipulator.class
    Class<?> _class = Class.forName(operator.getName());
    Constructor<?> _constructor = _class.getDeclaredConstructor();
    Object _instanceObj = _constructor.newInstance();
    //I need instance from the class I've passed, so I recreated the class in my method and pointed to it's instance.
    for (int i = 0; i < fields.length; i++){
        Field f = fields[i];
        f.setAccessible(true);
        //since fields can be private, I make them accessible to this method.
        Object value = f.get(_instanceObj);
        if(s.equals(f.getName())){
            s = value.toString();
            //if user's string matches the name of object, I replace this string with value of the object.
       }
    }
    return s;
}
    
}