/*

Project 4-1

Convert the help system from Project 3-3 into a Help class.

*/

class Help {

void helpon(int what) {

switch(what) {

case '1':

System.out.println("The if:\n");

System.out.println("if(condition) statement;");

System.out.println("else statement;");

break;

case '2':

System.out.println("The switch:\n");

System.out.println("switch(expression) {");

System.out.println(" case constant:");

System.out.println(" statement sequence");

System.out.println(" break;");

System.out.println(" // ...");

System.out.println("}");

break;

case '3':

System.out.println("The for:\n");

System.out.println("for(initialization; condition; iteration) statement;");

break;

case '4':

System.out.println("The while:\n");

System.out.println("while(condition) statement;");

break;

case '5':

System.out.println("The do-while:\n");

System.out.println("do {");

System.out.println(" statement;");

System.out.println("} while (condition);");

break;

case '6':

System.out.println("The break:\n");

System.out.println("break; or break label;");

break;

case '7':

System.out.println("The continue:\n");

System.out.println("continue; or continue label;");

break;

}

System.out.println();

}

void showmenu() {

System.out.println("Help on:");

System.out.println(" 1. if");

System.out.println(" 2. switch");

System.out.println(" 3. for");

System.out.println(" 4. while");

System.out.println(" 5. do-while");

System.out.println(" 6. break");

System.out.println(" 7. continue\n");

System.out.print("Choose one (q to quit): ");

}

boolean isvalid(int ch) {

if(ch < '1' | ch > '7' & ch != 'q') return false;

else return true;

}

}

class HelpClassDemo {

public static void main(String args[]) throws java.io.IOException {

char choice;

Help hlpobj = new Help();

for(;;) {

do {

hlpobj.showmenu();

do {

choice = (char) System.in.read();

} while(choice == '\n' | choice == '\r');

} while( !hlpobj.isvalid(choice) );

if(choice == 'q') break;

System.out.println("\n");

hlpobj.helpon(choice);

}

}

}