MyProgrammingLab - Chapter 5: Methods (Tony Gaddis)

The Math class provides a static method, max, that accepts two int arguments and returns the value of the larger one. Four int variables, population1, population2, population3, and population4 have already been declared and initialized. Write an expression (not a statement!) whose value is the largest of population1, population2, population3, and population4 by calling max.

Math.max(Math.max(population1, population2), Math.max(population3, population4))

The Math class provides a static method, max, that accepts two int arguments and returns the value of the larger one. Two int variables,population1 and population2, have already been declared and initialized. Write an expression (not a statement!) whose value is the larger of population1 and population2 by calling max.

Math.max(population1, population2)

Assume that x is a variable that has been declared as a double and been given a value. Write an expression to compute the quartic root of x. The quartic root of a number is the square root of its square root. EXAMPLES: For example, the quartic root of 16.0 is 2.0 because: the square root of 16.0 is 4.0 and the square root of 4.0 is 2.0. Another example: the quartic root of 81.0 is 3.0 because the square root of 81.0 is 9.0 and the square root of 9.0 is 3.0. Thus, to find the quartic root of a number you take the square root of the number and then take the square root of that. In this exercise you must find the quartic root of x in a single expression-- you must not write any statements. Also, you may only use the sqrt() static method defined in the Math class-- no other methods. (HINT: you will need to call the Math.sqrt() method twice-- and you will need to pass the return value of one of those calls as argument to the other call. AND REMEMBER: write an expression, not a statement.)

Math.sqrt(Math.sqrt(x))

toThePowerOf is a method that accepts two int arguments and returns the value of the first parameter raised to the power of the second. An int variable cubeSide has already been declared and initialized. Another int variable, cubeVolume, has already been declared. Write a statement that calls toThePowerOf to compute the value of cubeSide raised to the power of 3 and that stores this value in cubeVolume. Assume that toThePowerOf is defined in the same class that calls it.

cubeVolume = toThePowerOf(cubeSide, 3);

Given that a method receives three parameters a, b, c, of type double, write some code, to be included as part of the method, that determines whether the value of "b squared" - 4ac is negative. If negative, the code prints out the message "no real solutions" and returns from the method

double val = Math.pow(b,2) - 4*a*c; if(val < 0) { System.out.print("no real solutions"); return; }

add is a method that accepts two int arguments and returns their sum. Two int variables, euroSales and asiaSales, have already been declared and initialized. Another int variable, eurasiaSales, has already been declared. Write a statement that calls add to compute the sum of euroSales and asiaSales and that stores this value in eurasiaSales. Assume that add is defined in the same class that calls it.

eurasiaSales = add(euroSales, asiaSales);

Given that a method receives three parameters a, b, c, of type double, write some code, to be included as part of the method, that checks to see if the value of a is 0; if it is, the code prints the message "no solution for a=0" and returns from the method.

if(a == 0) { System.out.println("no solution for a=0"); return; }

Given the integer variables x and y, write a fragment of code that assigns the larger of x and y to another integer variable max.

max = x > y ? x : y;

max is a method that accepts two int arguments and returns the value of the larger one. Four int variables, population1, population2, population3, and population4 have already been declared and initialized. Write an expression (not a statement!) whose value is the largest of population1, population2, population3, and population4 by calling max. Assume that max is defined in the same class that calls it.

max(max(population1, population2), max(population3, population4))

max is a method that accepts two int arguments and returns the value of the larger one. Two int variables, population1 and population2, have already been declared and initialized. Write an expression (not a statement!) whose value is the larger of population1 and population2 by calling max. Assume that max is defined in the same class that calls it.

max(population1, population2)

Given the integer variables x, y, and z, write a fragment of code that assigns the smallest of x, y, and z to another integer variable min. Assume that all the variables have already been declared and that x, y, and z have been assigned values.

min = x < y && x < z ? x : y < z && y < x ? y : z < x ? z : x;

Assume that x is a variable that has been declared as an int and been given a value. Assume that oneMore is a function that receives a single integer parameter and returns a value that is one greater than its argument. (So if you pass 7 to oneMore it will return 8. Thus, the expression oneMore(9) has the value 10. Write an expression whose value is four more than x without using the standard Java arithmetic operators (*,+, etc.). Instead, use calls to oneMore to accomplish this. In this exercise you must write this as a single expression-- you must not write any statements. Also, you may only use the oneMore function-- no other functions or operators.

oneMore(oneMore(oneMore(oneMore(x))))

printErrorDescription is a method that accepts one int argument and returns no value. Write a statement that invokes the method printErrorDescription, passing it the value 14. Assume that printErrorDescription is defined in the same class that calls it.

printErrorDescription(14);

printLarger is a method that accepts two int arguments and returns no value. Two int variables, sales1 and sales2, have already been declared and initialized. Write a statement that calls printLarger, passing it sales1 and sales2. Assume that printLarger is defined in the same class that calls it.

printLarger(sales1, sales2);

printStars is a method that accepts a single int argument and returns no value. It prints as many stars as indicated by its argument. Given a variable x of type double that has been given a value, write a statement that invokes printStars passing x as an argument. Assume that printStars is defined in the same class that calls it.

printStars(x);

printTodaysDate is a method that accepts no arguments and returns no value. Write a statement that calls printTodaysDate. Assume that printTodaysDate is defined in the same class that calls it.

printTodaysDate();

Write a method, makeSubjectLine, that gets a String argument and returns the same String but with "Subject: " in front of it. So if the argument is "Are you going to the show?" the method returns "Subject: Are you going to the show?".

public static String makeSubjectLine(String a) { return "Subject: " + a; }

Write a method max that has two string parameters and returns the larger of the two.

public static String max(String a, String b) { return a.compareTo(b) > 0 ? a : b; }

Write a method min that has three string parameters and returns the smallest.

public static String min(String a, String b, String c) { return a.compareTo(b) < 0 && a.compareTo(c) < 0 ? a : b.compareTo(a) < 0 && b.compareTo(c) < 0 ? b : c; }

Write the definition of a method powerTo, which receives two parameters. The first is a double and the second is an int. The method returns a double. If the second parameter is negative, the method returns zero. Otherwise it returns the value of the first parameter raised to the power of the second parameter.

public static double powerTo(double in, int pow) { if(pow < 0) return 0; return Math.pow(in, pow); }

Write the definition of a method add, which receives two integer parameters and returns their sum.

public static int add(int arg1, int arg2) { return arg1+arg2; }

Write the definition of a method max that has three int parameters and returns the largest.

public static int max(int a, int b, int c) { return a > b && a > c ? a : b > a && b > c ? b : c > a && c > a ? c : a; }

Write the definition of a method min that has two int parameters and returns the smaller.

public static int min(int a, int b) { return a < b ? a : b; }

Write the definition of a method twice, which receives an integer parameter and returns an integer that is twice the value of the parameter.

public static int twice(int arg1) { return arg1*2; }

Write the definition of a method dashedLine, with one parameter, an int. If the parameter is negative or zero, the method does nothing. Otherwise it prints a complete line terminated by a newline to standard output consisting of dashes (hyphens) with the parameter's value determining the number of dashes. The method returns nothing.

public static void dashedLine(int arg1) { if(arg1 > 0) { for( int i = 0; i < arg1; i++) { System.out.print("-"); } System.out.println(); } }

Write the definition of a method printAttitude, which has an int parameter and returns nothing. The method prints a message to standard output depending on the value of its parameter. If the parameter equals 1, the method prints disagree If the parameter equals 2, the method prints no opinion If the parameter equals 3, the method prints agree In the case of other values, the method does nothing. Each message is printed on a line by itself.

public static void printAttitude(int at) { String message; switch(at) { case 1: message = "disagree"; break; case 2: message = "no opinion"; break; case 3: message = "agree"; break; default: message = ""; } System.out.println(message); }

Write the definition of a method printDottedLine, which has no parameters and doesn't return anything. The method prints to standard output a single line (terminated by a newline) consisting of five periods.

public static void printDottedLine() { System.out.println("....."); }

Write the definition of a method printGrade, which has a char parameter and returns nothing. The method prints on a line by itself the message string Grade: followed by the char parameter (printed as a character) to standard output. Don't forget to put a new line character at the end of your line.

public static void printGrade(char grade) { System.out.printf("Grade: %c\n", grade); }

Write the definition of a method printLarger, which has two int parameters and returns nothing. The method prints the larger value of the two parameters to standard output on a single line by itself.

public static void printLarger(int one, int two) { System.out.println(one>two?one:two); }

Write the code for invoking a method named sendNumber . There is one int argument for this method. Send the number 5 as an argument to this method. Assume that sendNumber is defined in the same class that calls it.

sendNumber(5);

Write the code for invoking a method named sendObject. There is one argument for this method which is of type Customer. Assume that there is a reference to an object of type Customer, in a variable called John_Doe. Use this reference as your argument. Assume that sendObject is defined in the same class that calls it.

sendObject(John_Doe);

Write the code for invoking a method named sendSignal. There are no arguments for this method. Assume that sendSignal is defined in the same class that calls it.

sendSignal();

Write the code for invoking a method named sendTwo. There are two arguments for this method: a double and an int. Invoke the method with the double value of 15.955 and the int value of 133. Assume that sendTwo is defined in the same class that calls it.

sendTwo(15.955, 133);

Write the code for invoking a method named sendVariable. There is one int argument for this method. Assume that an int variable called x has already been declared and initialized to some value. Use this variable's value as an argument in your method invocation. Assume that sendVariable is defined in the same class that calls it.

sendVariable(x);

Assume that x is a variable that has been declared as an int and been given a value. Assume that twice is a method (in the same class as the caller) that receives a single integer parameter and returns twice its value. (So if you pass 7 to twice it will return 14. Thus the expression twice(7) has the value 14. Write an expression whose value is eight times that of x without using the standard Java arithmetic operators (*,+, etc.). Instead, use calls to twice to accomplish this. In this exercise you must write this as a single expression-- you must not write any statements. Also, you may only use the twice() function-- no other functions or operators.

twice(twice(twice(x)))