1. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 01321308071 Chapter 3 Selections

2. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 2 Program Execution Structure Compiler executes in three different ways: Sequences Selection ( If Statement) Loop ( Repetition /Iteration) Process 1 Process 3 Process 2

3. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 01321308073 Objectives F To declare boolean type and write Boolean expressions using comparison operators (§3.2). F To program AdditionQuiz using Boolean expressions (§3.3). F To implement selection control using one-way if statements (§3.4) F To program the GuessBirthday game using one-way if statements (§3.5). F To implement selection control using two-way if statements (§3.6). F To implement selection control using nested if statements (§3.7). F To avoid common errors in if statements (§3.8). F To program using selection statements for a variety of examples (BMI, ComputeTax, SubtractionQuiz) (§3.9-3.11). F To generate random numbers using the Math.random() method (§3.9). F To combine conditions using logical operators (&&, ||, and !) (§3.12). F To program using selection statements with combined conditions (LeapYear, Lottery) (§§3.13-3.14). F To implement selection control using switch statements (§3.15). F To write expressions using the conditional operator (§3.16). F To format output using the System.out.printf method and to format strings using the String.format method (§3.17). F To examine the rules governing operator precedence and associativity (§3.18). F (GUI) To get user confirmation using confirmation dialogs (§3.19).

4. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 4 The boolean Type and Operators Often in a program you need to compare two values, such as whether i is greater than j. Java provides six comparison operators (also known as relational operators) that can be used to compare two values. The result of the comparison is a Boolean value: true or false. boolean b = (1 > 2);

5. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 5 Comparison Operators Operator Name < less than <= less than or equal to > greater than >= greater than or equal to == equal to != not equal to Relational operations

6. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 6 Problem: A Simple Math Learning Tool AdditionQuiz Run This example creates a program to let a first grader practice additions. The program randomly generates two single-digit integers number1 and number2 and displays a question such as “What is 7 + 9?” to the student. After the student types the answer, the program displays a message to indicate whether the answer is true or false.

7. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 Example –Listing 3.1 import java.util.Scanner; public class AdditionQuiz { public static void main(String[] args) { int number1 = (int)(System.currentTimeMillis() % 10); int number2 = (int)(System.currentTimeMillis() * 7 % 10); // Create a Scanner Scanner input = new Scanner(System.in); System.out.print( "What is " + number1 + " + " + number2 + "? "); int answer = input.nextInt(); System.out.println( number1 + " + " + number2 + " = " + answer + " is " + (number1 + number2 == answer)); } } 7 AdditionQuiz Chapter 3.1 - Program Addition Quiz Video Chapter 3.1 - Program Addition Quiz Video Run

8. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 8 One-way if Statements if (boolean-expression) { statement(s); } if (radius >= 0) { area = radius * radius * PI; System.out.println("The area" + " for the circle of radius " + radius + " is " + area); }

9. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 9 Note { is for beginning and end; curly braces, use { and } to define the limits of compound statements and surrounding the body of the loop and/or statement

10. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 10 Simple if Demo SimpleIfDemo Run Write a program that prompts the user to enter an integer. If the number is a multiple of 5, print HiFive. If the number is divisible by 2, print HiEven. Chapter 3- Listing 3.2 import java.util.Scanner; public class SimpleIfDemo { public static void main(String[] args) { Scanner input = new Scanner(System.in); System.out.println("Enter an integer: "); int number = input.nextInt(); if (number % 5 == 0) System.out.println("HiFive"); if (number % 2 == 0) System.out.println("HiEven"); } } Enter an interger 5 Hi five Enter an integer: 30 HiFive HiEven

11. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 11 Problem: Guessing Birthday GuessBirthday The program can guess your birth date. Run to see how it works.

12. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 12 Mathematics Basis for the Game 19 is 10011 in binary. 7 is 111 in binary. 23 is 11101 in binary

13. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 13 The Two-way if Statement if (boolean-expression) { statement(s)-for-the-true-case; } else { statement(s)-for-the-false-case; }

14. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 14 if...else Example if (radius >= 0) { area = radius * radius * 3.14159; System.out.println("The area for the “ + “circle of radius " + radius + " is " + area); } else { System.out.println("Negative input"); }

15. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 15 Multiple Alternative if Statements

16. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 16 Trace if-else statement if (score >= 90.0) grade = 'A'; else if (score >= 80.0) grade = 'B'; else if (score >= 70.0) grade = 'C'; else if (score >= 60.0) grade = 'D'; else grade = 'F'; Suppose score is 70.0The condition is false animation

17. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 17 Trace if-else statement if (score >= 90.0) grade = 'A'; else if (score >= 80.0) grade = 'B'; else if (score >= 70.0) grade = 'C'; else if (score >= 60.0) grade = 'D'; else grade = 'F'; Suppose score is 70.0The condition is false animation

18. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 18 Trace if-else statement if (score >= 90.0) grade = 'A'; else if (score >= 80.0) grade = 'B'; else if (score >= 70.0) grade = 'C'; else if (score >= 60.0) grade = 'D'; else grade = 'F'; Suppose score is 70.0The condition is true animation

19. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 19 Trace if-else statement if (score >= 90.0) grade = 'A'; else if (score >= 80.0) grade = 'B'; else if (score >= 70.0) grade = 'C'; else if (score >= 60.0) grade = 'D'; else grade = 'F'; Suppose score is 70.0grade is C animation

20. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 20 Trace if-else statement if (score >= 90.0) grade = 'A'; else if (score >= 80.0) grade = 'B'; else if (score >= 70.0) grade = 'C'; else if (score >= 60.0) grade = 'D'; else grade = 'F'; Suppose score is 70.0Exit the if statement animation

21. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 21 Note The else clause matches the most recent if clause in the same block.

22. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 22 Note, cont. Nothing is printed from the preceding statement. To force the else clause to match the first if clause, you must add a pair of braces: int i = 1; int j = 2; int k = 3; if (i > j) { if (i > k) System.out.println("A"); } else System.out.println("B"); This statement prints B.

23. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 23 Common Errors Adding a semicolon at the end of an if clause is a common mistake. if (radius >= 0); { area = radius*radius*PI; System.out.println( "The area for the circle of radius " + radius + " is " + area); } This mistake is hard to find, because it is not a compilation error or a runtime error, it is a logic error. This error often occurs when you use the next-line block style. Wrong

24. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 24 Problem: An Improved Math Learning Tool This example creates a program to teach a first grade child how to learn subtractions. The program randomly generates two single- digit integers number1 and number2 with number1 > number2 and displays a question such as “What is 9 – 2?” to the student. After the student types the answer in the input dialog box, the program displays a message dialog box to indicate whether the answer is correct. SubtractionQuiz

25. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 Example – Listing 3.4 import java.util.Scanner; public class SubtractionQuiz { public static void main(String[] args) { // 1. Generate two random single-digit integers int number1 = (int)(Math.random() * 10); int number2 = (int)(Math.random() * 10); // 2. If number1 < number2, swap number1 with number2 if (number1 < number2) { int temp = number1; number1 = number2; number2 = temp; } // 3. Prompt the student to answer “what is number1 – number2?” System.out.print ("What is " + number1 + " - " + number2 + "? "); Scanner input = new Scanner(System.in); int answer = input.nextInt(); // 4. Grade the answer and display the result if (number1 - number2 == answer) System.out.println("You are correct!"); else System.out.println("Your answer is wrong.\n" + number1 + " - " + number2 + " should be " + (number1 - number2)); } } 25 SubtractionQuiz jGRASP exec: java SubtractionQuiz What is 5 - 2? 3 You are correct! --jGRASP: operation complete. --jGRASP exec: java SubtractionQuiz What is 9 - 4? 6 Your answer is wrong. - 4 should be 5 Chapter 3.1: Program Subtraction Quiz Video Chapter 3.1: Program Subtraction Quiz Video

26. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 26 Problem: Body Mass Index Body Mass Index (BMI) is a measure of health on weight. It can be calculated by taking your weight in kilograms and dividing by the square of your height in meters. The interpretation of BMI for people 16 years or older is as follows: ComputeBMI

27. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 27 Problem: Computing Taxes The US federal personal income tax is calculated based on the filing status and taxable income. There are four filing statuses: single filers, married filing jointly, married filing separately, and head of household. The tax rates for 2009 are shown below. Marginal Tax Rate Single Married Filing Jointly or Qualified Widow(er) Married Filing Separately Head of Household 10%$0 – $8,350$0 – $16,700$0 – $8,350$0 – $11,950 15%$8,351– $33,950$16,701 – $67,900$8,351 – $33,950$11,951 – $45,500 25%$33,951 – $82,250$67,901 – $137,050$33,951 – $68,525$45,501 – $117,450 28%$82,251 – $171,550$137,051 – $208,850$68,525 – $104,425$117,451 – $190,200 33%$171,551 – $372,950$208,851 – $372,950$104,426 – $186,475$190,201 - $372,950 35%$372,951+ $186,476+$372,951+

28. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 28 Problem: Computing Taxes, cont. ComputeTax if (status == 0) { // Compute tax for single filers } else if (status == 1) { // Compute tax for married file jointly } else if (status == 2) { // Compute tax for married file separately } else if (status == 3) { // Compute tax for head of household } else { // Display wrong status }

29. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 29 Logical Operators Operator Name ! not && and || or ^ exclusive or

30. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 30 Truth Table for Operator ! (Not)

31. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 31 Truth Table for Operator && (And)

32. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 32 Truth Table for Operator || (Not)

33. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 33 Examples Here is a program that checks whether a number is divisible by 2 and 3, but not both: TestBooleanOperators Run import java.util.Scanner; public class TestBooleanOperators { public static void main(String[] args) { // Create a Scanner Scanner input = new Scanner(System.in); // Receive an input System.out.print("Enter an integer: "); int number = input.nextInt(); System.out.println("Is " + number + " divisible by 2 and 3? " + ((number % 2 == 0) && (number % 3 == 0))); System.out.println("Is " + number + " divisible by 2 or 3? " + ((number % 2 == 0) || (number % 3 == 0))); System.out.println("Is " + number + " divisible by 2 or 3, but not both? " + ((number % 2 == 0) ^ (number % 3 == 0))); } } TestBooleanOperators Enter an integer: 45 Is 45 divisible by 2 and 3? False Is 45 divisible by 2 or 3? True Is 45 divisible by 2 or 3, but not both? True ----jGRASP: operation complete.

34. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 34 Truth Table for Operator !

35. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 35 Truth Table for Operator &&

36. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 36 Truth Table for Operator ||

37. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 37 Truth Table for Operator ^ (invert)

38. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 38 Examples System.out.println("Is " + number + " divisible by 2 and 3? " + ((number % 2 == 0) && (number % 3 == 0))); System.out.println("Is " + num ber + " divisible by 2 or 3? " + ((num ber % 2 == 0) || (num ber % 3 == 0))); System.out.println("Is " + num ber + " divisible by 2 or 3, but not both? " + ((num ber % 2 == 0) ^ (num ber % 3 == 0))); TestBooleanOperators Run

39. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 39 The & and | Operators If x is 1, what is x after this expression? (x > 1) & (x++ < 10) If x is 1, what is x after this expression? (1 > x) && ( 1 > x++) How about (1 == x) | (10 > x++)? (1 == x) || (10 > x++)? Companion Website

40. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 40 Problem: Determining Leap Year? LeapYearRun This program first prompts the user to enter a year as an int value and checks if it is a leap year. A year is a leap year if it is divisible by 4 but not by 100, or it is divisible by 400. (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)

41. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 41 Problem: Lottery Write a program that randomly generates a lottery of a two- digit number, prompts the user to enter a two-digit number, and determines whether the user wins according to the following rule: Lottery If the user input matches the lottery in exact order, the award is $10,000. If the user input matches the lottery, the award is $3,000. If one digit in the user input matches a digit in the lottery, the award is $1,000.

42. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 42 switch Statements The switch statement in Java are shorthand for a certain kind of if statement. It is not uncommon to se a stack of if statements all related to the same quantity like this. if (x == 0) doSomething0(); else if (x == 1) doSomething1(); else if (x == 2) doSomething2(); else if (x == 3) doSomething3(); else if (x == 4) doSomething4(); else doSomethingElse();

43. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 The Switch statement in Java Java has a shorthand for these types of multiple if statements, the switch-case statement. Here's how you'd write the above using a switch-case: switch (status) { case 0: compute taxes for single filers; break; case 1: compute taxes for married file jointly; break; case 2: compute taxes for married file separately; break; case 3: compute taxes for head of household; break; default: System.out.println("Errors: invalid status"); System.exit(0); } 43

44. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 44 switch Statement Flow Chart

45. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 45 switch Statement Rules switch (switch-expression) { case value1: statement(s)1; break; case value2: statement(s)2; break; … case valueN: statement(s)N; break; default: statement(s)-for-default; } The switch-expression must yield a value of char, byte, short, or int type and must always be enclosed in parentheses. The value1,..., and valueN must have the same data type as the value of the switch-expression. The resulting statements in the case statement are executed when the value in the case statement matches the value of the switch- expression. Note that value1,..., and valueN are constant expressions, meaning that they cannot contain variables in the expression, such as 1 + x.

46. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 46 switch Statement Rules The keyword break is optional, but it should be used at the end of each case in order to terminate the remainder of the switch statement. If the break statement is not present, the next case statement will be executed. switch (switch-expression) { case value1: statement(s)1; break; case value2: statement(s)2; break; … case valueN: statement(s)N; break; default: statement(s)-for-default; } The default case, which is optional, can be used to perform actions when none of the specified cases matches the switch-expression. The case statements are executed in sequential order, but the order of the cases (including the default case) does not matter. However, it is good programming style to follow the logical sequence of the cases and place the default case at the end.

47. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 The switch Statement F Unlike if-then and if-then-else statements, the switch statement can have a number of possible execution paths. A switch works with the byte, short, char, and int primitive data types. It also works with enumerated types, the String class, and a few special Classes that wrap certain primitive types: Character, Byte, Short, and integer. F The following code example, Switch Demo, declares an int named month whose value represents a month. The code displays the name of the month, based on the value of month, using the switch statement. 47 The Switch StatementThe Switch Statement – Oracle web link Oracle web link The Switch StatementThe Switch Statement – Oracle web link Oracle web link

48. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 48 Trace switch statement switch (ch) { case 'a': System.out.println(ch); case 'b': System.out.println(ch); case 'c': System.out.println(ch); } Suppose ch is 'a': animation

49. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 49 Trace switch statement switch (ch) { case 'a': System.out.println(ch); case 'b': System.out.println(ch); case 'c': System.out.println(ch); } ch is 'a': animation

50. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 50 Trace switch statement switch (ch) { case 'a': System.out.println(ch); case 'b': System.out.println(ch); case 'c': System.out.println(ch); } Execute this line animation

51. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 51 Trace switch statement switch (ch) { case 'a': System.out.println(ch); case 'b': System.out.println(ch); case 'c': System.out.println(ch); } Execute this line animation

52. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 52 Trace switch statement switch (ch) { case 'a': System.out.println(ch); case 'b': System.out.println(ch); case 'c': System.out.println(ch); } Execute this line animation

53. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 53 Trace switch statement switch (ch) { case 'a': System.out.println(ch); case 'b': System.out.println(ch); case 'c': System.out.println(ch); } Next statement; Execute next statement animation

54. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 54 Trace switch statement switch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break ; case 'c': System.out.println(ch); } Suppose ch is 'a': animation

55. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 55 Trace switch statement switch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break ; case 'c': System.out.println(ch); } ch is 'a': animation

56. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 56 Trace switch statement switch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break ; case 'c': System.out.println(ch); } Execute this line animation

57. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 57 Trace switch statement switch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break ; case 'c': System.out.println(ch); } Execute this line animation

58. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 58 Trace switch statement switch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break ; case 'c': System.out.println(ch); } Next statement; Execute next statement animation

59. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 Sorting three integers public class Exercise3_8 { public static void main(String[] args) { java.util.Scanner input = new java.util.Scanner(System.in); // Enter three numbers System.out.print("Enter three integers: "); int num1 = input.nextInt(); int num2 = input.nextInt(); int num3 = input.nextInt(); if (num1 > num2) { int temp = num1; num1 = num2; num2 = temp; } if (num2 > num3) { int temp = num2; num2 = num3; num3 = temp; } if (num1 > num2) { int temp = num1; num1 = num2; num2 = temp; } System.out.println("The sorted numbers are " + num1 + " " + num2 + " " + num3); } } 59 Video - Sorting three integers Video - Sorting three integers

60. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 60 Conditional Operator if (x > 0) y = 1 else y = -1; is equivalent to y = (x > 0) ? 1 : -1; (boolean-expression) ? expression1 : expression2 Ternary operator Binary operator Unary operator

61. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 61 Conditional Operator if (num % 2 == 0) System.out.println(num + “is even”); else System.out.println(num + “is odd”); System.out.println( (num % 2 == 0)? num + “is even” : num + “is odd”);

62. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 62 Formatting Output Use the printf statement. System.out.printf(format, items); Where format is a string that may consist of substrings and format specifiers. A format specifier specifies how an item should be displayed. An item may be a numeric value, character, boolean value, or a string. Each specifier begins with a percent sign.

63. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 63 Frequently-Used Specifiers Specifier OutputExample %b a boolean value true or false %c a character 'a' %d a decimal integer 200 %f a floating-point number 45.460000 %e a number in standard scientific notation 4.556000e+01 %s a string "Java is cool"

64. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 64 Operator Precedence F var++, var--  +, - (Unary plus and minus), ++var, --var F (type) Casting F ! (Not)  *, /, % (Multiplication, division, and remainder)  +, - (Binary addition and subtraction) , >= (Comparison)  ==, !=; (Equality) F ^ (Exclusive OR) F && (Conditional AND) Short-circuit AND F || (Conditional OR) Short-circuit OR  =, +=, -=, *=, /=, %= (Assignment operator)

65. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 65 Operator Precedence and Associativity The expression in the parentheses is evaluated first. (Parentheses can be nested, in which case the expression in the inner parentheses is executed first.) When evaluating an expression without parentheses, the operators are applied according to the precedence rule and the associativity rule. If operators with the same precedence are next to each other, their associativity determines the order of evaluation. All binary operators except assignment operators are left-associative.

66. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 66 Operator Associativity When two operators with the same precedence are evaluated, the associativity of the operators determines the order of evaluation. All binary operators except assignment operators are left- associative. a – b + c – d is equivalent to ((a – b) + c) – d Assignment operators are right-associative. Therefore, the expression a = b += c = 5 is equivalent to a = (b += (c = 5))

67. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 67 Example Applying the operator precedence and associativity rule, the expression 3 + 4 * 4 > 5 * (4 + 3) - 1 is evaluated as follows:

68. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 68 (GUI) Confirmation Dialogs int option = JOptionPane.showConfirmDialog (null, "Continue");

69. Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 69 Problem: Guessing Birth Date GuessBirthDateUsingConfirmationDialog The program can guess your birth date. Run to see how it works.