U experienced in telnet?

Question

As your probably know, 2 of the few of the things that you need in telnet is an inputStream and an outputStream. I am constantly listening to my inputStream with a while loop and displaying back that input into the telnet client. But this constant 'listening' has backfired with high CPU load when input is expected. I only exit the listening when either carriage return is encountered or user has input max characters. Anyone knows how to decrease the CPU load?? I cannot get the indentation on this discussion group.
//prompts user for input,
//returns the input string,
//characters not in key_list are ignored
public String getString() throws Exception{
boolean flag=true;
char last_char;
int v_ascii;
     int ran_ascii;
     int i=0;
     while(flag){ //print the user input live
     i=i+1;
               if (in.ready()){ //is there anything to read?
                    v_ascii=in.read(); //get the char by char input from the keyboard, NOTE:read returns an int
                    last_char=(char)v_ascii;
                    System.out.println("User is putting in '"+last_char+"' which is ASCII '"+v_ascii+"'");
                    if (is_allowable(v_ascii)){ //ignore special characters
                    if (v_ascii==8){ //treat a backspace differently
                         if (this.backspace(1)){ //successful backspace, v_string modified
                    out.print(last_char); //last_char is a backspace here
                              out.print((char)32);//print a space
                              out.print(last_char);//do another backspace again
                    out.flush(); //make it visible
                         }//no need to append, last char has been removed
                    else{  //it is not a backspace
               if( (v_ascii==10) || (v_ascii==13) ){ //carriage return entered, terminate input
               flag=false; //exit the for loop
                              //this.appendEnter(); //append chr10 and 13
                              this.terminateInput(); //move pointer to last input character
                         else{//all allowable input characters
                         if (v_string.toString().length()<maxlen){ //more characters are still allowed
                         v_string.append(last_char);//append the legal character to string input
                         if (is_visible){
                    out.print(last_char); //return what the user is typing in on his screen
                    out.flush(); //make it visible                    
                                   else{//not supposed to be visible                                     
                                   //ran_ascii=(int)(ran.nextInt(7)+162);//try this funny thing out
                                   //out.print( (char)ran_ascii );
                                   out.print('*');//to substitute passwords
                                   out.flush();
                    }//v_string.len < maxlen
                         if (v_string.toString().length()==maxlen && is_autoenter){//force input termination
                              flag=false;
                              //this.appendEnter(); //append chr10 and 13
                              this.terminateInput(); //stop reading
                         }//else did not press carriage return
                    }//else no backspace
               }//is_allowable, keys are legal
               }//if in.ready()
          } //while loop
return (v_string.toString().trim()); //return the user input     in String, trim it to remove the carriage return

Answer 1

Use [ code ](no spaces) before the snippet, and [ /code ](no spaces) after for indentation.
Now to your question. Maybe you should use a seperate thread the listen on the input, then you won't have to test in.ready() repeatedly. Tou can have the thread block on the read.
public clas ReadingStuff implements Runnable {
    public void run(){
     while(your_boolean) {
            try {
                String s = getString();
            catch(Exception e){}
        //prompts user for input,
    //returns the input string,
    //characters not in key_list are ignored
    public String getString() throws Exception{
        boolean flag=true;
        char last_char;
        int v_ascii;
        int ran_ascii;
        int i=0;
        while(flag){ //print the user input live
            i=i+1;
//removed: if(in.ready()){
            v_ascii=in.read(); //get the char by char input from the keyboard, NOTE:read returns an int
            last_char=(char)v_ascii;
            System.out.println("User is putting in '"+last_char+"' which is ASCII '"+v_ascii+"'");
            if (is_allowable(v_ascii)){ //ignore special characters
                if (v_ascii==8){ //treat a backspace differently
                    if (this.backspace(1)){ //successful backspace, v_string modified
                        out.print(last_char); //last_char is a backspace here
                        out.print((char)32);//print a space
                        out.print(last_char);//do another backspace again
                        out.flush(); //make it visible
                    }//no need to append, last char has been removed
                else{ //it is not a backspace
                    if( (v_ascii==10) || (v_ascii==13) ){ //carriage return entered, terminate input
                        flag=false; //exit the for loop
                        //this.appendEnter(); //append chr10 and 13
                        this.terminateInput(); //move pointer to last input character
                    else{//all allowable input characters
                        if (v_string.toString().length()<maxlen){ //more characters are still allowed
                            v_string.append(last_char);//append the legal character to string input
                                if (is_visible){
                                    out.print(last_char); //return what the user is typing in on his screen
                                    out.flush(); //make it visible
                                else{//not supposed to be visible
                                    //ran_ascii=(int)(ran.nextInt(7)+162);//try this funny thing out
                                    //out.print( (char)ran_ascii );
                                    out.print('*');//to substitute passwords
                                    out.flush();
                        }//v_string.len < maxlen
                        if (v_string.toString().length()==maxlen && is_autoenter){//force input termination
                            flag=false;
                            //this.appendEnter(); //append chr10 and 13
                            this.terminateInput(); //stop reading
                    }//else did not press carriage return
                }//else no backspace
            }//is_allowable, keys are legal
//Removed        }//if in.ready()
        } //while loop
        return (v_string.toString().trim()); //return the user input in String, trim it to remove the carriage return