ASCII Table

[NOTSOSURE]

i am experamenting with JAVA.

I wanna write a program which will print an ASCII values table using a for loop.

So if i type in a Start Value of "A" and a Last Value of "}" the output should be

ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}

Error conditions
================
If the last character is before the start character print an error message saying:

"Error - last is before start"

Here is the code i have writen so far.. but i cant get the output to show can any one tell me where i am going wrong.

public class Ascii {


    public static void main(String[] argv) {

    char startChar, lastChar;
    String ascii = "";
    
    System.out.println ("Please type the start character");
    startChar = UserInput.readChar();
    
    System.out.println ("Please type the last character");
    lastChar = UserInput.readChar();
    
    if (lastChar < startChar){
        System.out.println ("Error, last character is before start character");
    }
    
    for (startChar = startChar; startChar == lastChar; ++startChar){
        
    }

    ascii = ascii + startChar;

    System.out.println (ascii);
    } // end of main
    
} // end class

thanx ppl