In the heading public static int total(int a, int b), what is int a?
Which part of a method heading tells the compiler what kind of value the method sends back?
What must a method whose return type is double do?
Which statement about a void method is correct?
What is the output?
public class Pass {
public static void change(int n) { n = 100; }
public static void main(String[] args) {
int x = 5;
change(x);
System.out.print(x);
}
}
Why can a Java method not swap two int variables belonging to its caller?
A method receives an array as a parameter and changes arr[0]. The caller:
The same method then executes arr = new int[5];. After the call, the caller's array:
Which of the following is a valid overload of void print(int x)?
Which is not a valid way to overload a method?
What will the following program output?
class Calculator {
void multiply(int a, int b) { System.out.print("Hi"); }
void multiply(double a, double b) { System.out.print("HD"); }
public static void main(String[] args) {
Calculator calc = new Calculator();
calc.multiply(5, 3.0);
System.out.print(" and ");
calc.multiply(5.0, 3);
}
}
What will the following program output?
class Calculator {
int add(int a, int b) { return a + b; }
double add(int a, int b) { return a + b; }
public static void main(String[] args) {
System.out.println(new Calculator().add(2, 3));
}
}
What is the output of the following application?
public class ChooseWisely {
public int choose(int choice) { return 5; }
public int choose(short choice) { return 2; }
public int choose(long choice) { return 11; }
public static void main(String[] path) {
System.out.print(new ChooseWisely().choose((byte)2 + 1));
}
}
Which statement about static methods is correct?
Which of these is the best candidate to be declared static?
A utility class such as Math:
What is the value of Math.pow(2, 3)?
Which line does not compile?
What is the value of Math.ceil(4.1)?
What is the value of Math.floor(-4.1)?
What is the value of Math.round(4.5)?
What is the range of values returned by Math.random()?
Which expression produces a random integer from 1 to 6 inclusive?
Which expression gives a random integer between 10 and 20 inclusive?
Which method converts the String "42" into the int 42?
What is the wrapper class for char?
What does Character.isDigit('7') return?
What does Character.toUpperCase('a') return?
What is Integer.MAX_VALUE used for?
Autoboxing refers to:
What does System.out.printf("%.2f", 3.14159) print?
Which format specifier prints a whole number?
What does the minus sign in %-10s mean?
What is printed?
public class Helper {
private static int square(int n) { return n * n; }
public static void main(String[] args) {
System.out.print(square(square(2)));
}
}
What is the output?
public class Counter {
static int count = 0;
static void bump() { count++; }
public static void main(String[] args) {
bump(); bump(); bump();
System.out.print(count);
}
}
Which method call is illegal, given
public static double area(double w, double h)?
What is the output?
public class Early {
public static void check(int n) {
if (n < 0) return;
System.out.print("ok");
}
public static void main(String[] args) { check(-5); check(5); }
}
Explain, with a small example, why a method that takes an int
parameter cannot change the caller's variable, while a method that takes an array parameter can
change the caller's data.
State the rule that decides whether two methods are valid overloads,
and explain why int f(int x) and double f(int x) cannot coexist.
Write a utility class MathUtil containing: a public static final double named GOLDEN_RATIO; a static method isPrime(int n) returning a
boolean; a static method max3(int a, int b, int c); and two overloaded
static methods average — one taking two ints and one taking three. Add a
main method that tests each of them and prints the results with printf, showing two
decimal places for the averages.