How to modify tostring() method in java without using stringbuilder ?

Hi guys,

In an exercise on toString() methods in Java, our teacher asks us to write the following method without using StringBuilder : 

public String toString() {
		StringBuilder concatchar = new StringBuilder();
		if (value >= 2 && (value <= 10){
			concatchar.append(value);
		}else if (value == 11){
			concatchar.append("Jack");
		}else if (value == 12){
			concatchar.append("Queen");
		}else if (value == 13){
			concatchar.append("King");	
		}else if (value == 14){
			concatchar.append("Ace");
			}
		concatchar.append(" of ");
		concatchar.append(color.toString());
		return concatchar.toString();
	}


I know I have a problem with the type of my data. But I don't know how to get out of it. In addition, I have to manage several values for 11, 12, 13 and 14. 

Thanks ;-)

What I have tried:

<pre>I tried with the "+" operator and the concat() method but without success. Is it possible with "+" or concat() please ? If I try with <pre><pre lang="Java">value + " of " + color.toString()