Java руководство для начинающих - Шилдт Герберт (2012)

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(" // ...");

140 Java 7: руководство для начинающих, 5-е издание

System.out.println("}");

break;

case '3':

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

System.out.print("for(init; condition; iteration)");

System.out.println(" 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();

}

Далее создайте метод showmenu (), исходный код которого приведен ниже.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): ");

}

И наконец, создайте метод is valid (), исходный код которого приведен ниже.boolean isvalid(int ch) {

if(ch < 'l1 | ch > *7' & ch != fq') return false;

else return true;

}

Добавьте созданные выше методы в класс Help, как показано ниже.

class Help {

void helpon(int what) {

switch(what) {

case '1' :

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

Глава 4. Введение в классы, объекты и методы 141

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 .print'ln (" break;") ;

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

System.out.println("}");

break;

case '3':

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

System.out.print("for(init; condition; iteration)");

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

}