1. Chapter 3 Selections1Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 2. Motivations If you assigned a negative value for radius in Listing 2.1, ComputeArea.java, the program would print an invalid result. If the radius is negative, you don't want the program to compute the area. How can you deal with this situation?2Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 3. Objectives To declare boolean type and write Boolean expressions using comparison operators (§3.2). To program AdditionQuiz using Boolean expressions (§3.3). To implement selection control using one-way if statements (§3.4) To program the GuessBirthday game using one-way if statements (§3.5). To implement selection control using two-way if statements (§3.6). To implement selection control using nested if statements (§3.7). To avoid common errors in if statements (§3.8). To program using selection statements for a variety of examples (BMI, ComputeTax, SubtractionQuiz) (§3.9-3.11). To generate random numbers using the Math.random() method (§3.9). To combine conditions using logical operators (&&, ||, and !) (§3.12). To program using selection statements with combined conditions (LeapYear, Lottery) (§§3.13-3.14). To implement selection control using switch statements (§3.15). To write expressions using the conditional operator (§3.16). To format output using the System.out.printf method and to format strings using the String.format method (§3.17). To examine the rules governing operator precedence and associativity (§3.18). (GUI) To get user confirmation using confirmation dialogs (§3.19).3Liang, 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);4Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 5. Comparison Operators Operator Name =greater than or equal to==equal to!=not equal to 5Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 6. Problem: A Simple Math Learning Tool 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. RunAdditionQuiz 6Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 7. One-way if Statements if (boolean-expression) { statement(s); }Boolean Expressionfalseif (radius >= 0) { area = radius * radius * PI; System.out.println("The area" + " for the circle of radius " + radius + " is " + area); }(radius >= 0)falsetruetrue Statement(s)(A)area = radius * radius * PI; System.out.println("The area for the circle of " + "radius " + radius + " is " + area);(B)7Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 8. Note if i > 0 { System.out.println("i is positive"); }if (i > 0) { System.out.println("i is positive"); }(a) Wrongif (i > 0) { System.out.println("i is positive"); }(b) CorrectEquivalentif (i > 0) System.out.println("i is positive"); (b)(a)8Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 9. Simple if Demo 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.RunSimpleIfDemo 9Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 10. Problem: Guessing Birthday The program can guess your birth date. Run to see how it works. = 19 +1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 Set12 10 18 263 11 19 276 14 22 30Set27 15 23 314 5 6 7 12 13 14 15 20 21 22 23 28 29 30 318 9 10 11 12 13 14 15 24 25 26 27 28 29 30 31Set3Set4GuessBirthday16 20 24 2817 21 25 2918 22 26 3019 23 27 31Set5Run 10Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 11. Mathematics Basis for the Game 19 is 10011 in binary. 7 is 111 in binary. 23 is 11101 in binary 10000 10 + 1 1001110000 1000 100 + 1 1110100110 10 + 1 0011119723 = 19 +1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 Set12 10 18 263 11 19 276 14 22 30Set27 15 23 314 5 6 7 12 13 14 15 20 21 22 23 28 29 30 318 9 10 11 12 13 14 15 24 25 26 27 28 29 30 31Set3Set416 20 24 2817 21 25 2918 22 26 3019 23 27 31Set511Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 12. The Two-way if Statement if (boolean-expression) { statement(s)-for-the-true-case; } else { statement(s)-for-the-false-case; }trueStatement(s) for the true caseBoolean ExpressionfalseStatement(s) for the false case12Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 13. 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"); }13Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 14. Multiple Alternative if Statements 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';Equivalentif (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';14Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 15. animationTrace if-else statementSuppose score is 70.0The condition is falseif (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';15Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 16. animationTrace if-else statementSuppose score is 70.0The condition is falseif (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';16Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 17. animationTrace if-else statementSuppose score is 70.0The condition is trueif (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';17Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 18. animationTrace if-else statementSuppose score is 70.0grade is Cif (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';18Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 19. animationTrace if-else statementSuppose score is 70.0Exit the if statementif (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';19Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 20. Note The else clause matches the most recent if clause in the same block. int i = 1; int j = 2; int k = 3;Equivalentif (i > j) if (i > k) System.out.println("A"); else System.out.println("B");int i = 1; int j = 2; int k = 3; if (i > j) if (i > k) System.out.println("A"); else System.out.println("B");(a)(b)20Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 21. 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. 21Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 22. Common Errors Adding a semicolon at the end of an if clause is a common mistake. if (radius >= 0); Wrong { 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. 22Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 23. TIP if (number % 2 == 0) even = true; else even = false;Equivalentboolean even = number % 2 == 0; (b)(a)23Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 24. CAUTION if (even == true) System.out.println( "It is even.");Equivalentif (even) System.out.println( "It is even."); (b)(a)24Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 25. 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 singledigit 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. SubtractionQuizRun 25Liang, 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: BMIInterpretationbelow 16 16-18 18-24 24-29 29-35 above 35serious underweight underweight normal weight overweight seriously overweight gravely overweightComputeBMIRun 26Liang, 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. Married Filing Jointly Marginal Married Filing Tax RateSingleor Qualified Widow(er)Head of HouseholdSeparately10%$0 – $8,350$0 – $16,700$0 – $8,350$0 – $11,95015%$8,351– $33,950$16,701 – $67,900$8,351 – $33,950$11,951 – $45,50025%$33,951 – $82,250$67,901 – $137,050$33,951 – $68,525$45,501 – $117,45028%$82,251 – $171,550$137,051 – $208,850$68,525 – $104,425$117,451 – $190,20033%$171,551 – $372,950$208,851 – $372,950$104,426 – $186,475$190,201 - $372,95035%$372,951+$372,951+$186,476+$372,951+27Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 28. Problem: Computing Taxes, cont. 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 }ComputeTax28RunLiang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 29. Logical Operators Operator Name !not&&and||or^exclusive or29Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 30. Truth Table for Operator ! p!pExample (assume age = 24, gender = 'M')truefalse!(age > 18) is false, because (age > 18) is true.falsetrue!(gender != 'F') is true, because (grade != 'F') is false.30Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 31. Truth Table for Operator && p1p2p1 && p2Example (assume age = 24, gender = 'F')falsefalsefalsefalsetruefalse(age > 18) && (gender == 'F') is true, because (age > 18) and (gender == 'F') are both true.truefalsefalsetruetruetrue(age > 18) && (gender != 'F') is false, because (gender != 'F') is false.31Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 32. Truth Table for Operator || p1p2p1 || p2Example (assume age = 24, gender = 'F')falsefalsefalsefalsetruetrue(age > 34) || (gender == 'F') is true, because (gender == 'F') is true.truefalsetruetruetruetrue(age > 34) || (gender == 'M') is false, because (age > 34) and (gender == 'M') are both false.32Liang, 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, whether a number is divisible by 2 or 3, and whether a number is divisible by 2 or 3 but not both:TestBooleanOperatorsRun33Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 34. Truth Table for Operator ! p!ptruefalse!(1 > 2) is true, because (1 > 2) is false.falsetrue!(1 > 0) is false, because (1 > 0) is true.Example34Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 35. Truth Table for Operator && p1p2p1 && p2falsefalsefalsefalsetruefalsetruefalsefalsetruetruetrueExample (3 > 2) && (5 >= 5) is true, because (3 > 2) and (5 >= 5) are both true. (3 > 2) && (5 > 5) is false, because (5 > 5) is false.35Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 36. Truth Table for Operator || p1p2p1 || p2falsefalsefalsefalsetruetruetruefalsetruetruetruetrueExample (2 > 3) || (5 > 5) is false, because (2 > 3) and (5 > 5) are both false. (3 > 2) || (5 > 5) is true, because (3 > 2) is true.36Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 37. Truth Table for Operator ^ p1p2p1 ^ p2Example (assume age = 24, gender = 'F')falsefalsefalsefalsetruetrue(age > 34) ^ (gender == 'F') is true, because (age > 34) is false but (gender == 'F') is true.truefalsetruetruetruefalse(age > 34) || (gender == 'M') is false, because (age > 34) and (gender == 'M') are both false.37Liang, 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 " + 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? " +TestBooleanOperators((number % 2 == 0) ^ (number % 3 == 0)));Run 38Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 39. Companion WebsiteThe & and | OperatorsSupplement III.B, “The & and | Operators”39Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 40. Companion WebsiteThe & and | OperatorsIf 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++)? 40Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 41. Problem: Determining Leap Year? 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) LeapYearRun 41Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 42. Problem: Lottery Write a program that randomly generates a lottery of a twodigit number, prompts the user to enter a two-digit number, and determines whether the user wins according to the following rule: • 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. LotteryRun 42Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 43. switch Statements 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); } 43Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 44. switch Statement Flow Chart status is 0Compute tax for single filersbreakCompute tax for married file jointlybreakCompute tax for married file separatlybreakCompute tax for head of householdbreakstatus is 1status is 2status is 3default Default actionsNext Statement44Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 45. switch Statement Rules 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 switchexpression. Note that value1, ..., and valueN are constant expressions, meaning that they cannot contain variables in the expression, such as 1 + x.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; }45Liang, 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.The default case, which is optional, can be used to perform actions when none of the specified cases matches the switch-expression.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 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.46Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 47. animationTrace switch statementSuppose ch is 'a':switch case case case }(ch) 'a': 'b': 'c':{ System.out.println(ch); System.out.println(ch); System.out.println(ch);47Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 48. animationTrace switch statement ch is 'a':switch case case case }(ch) 'a': 'b': 'c':{ System.out.println(ch); System.out.println(ch); System.out.println(ch);48Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 49. animationTrace switch statement Execute this lineswitch case case case }(ch) 'a': 'b': 'c':{ System.out.println(ch); System.out.println(ch); System.out.println(ch);49Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 50. animationTrace switch statement Execute this lineswitch case case case }(ch) 'a': 'b': 'c':{ System.out.println(ch); System.out.println(ch); System.out.println(ch);50Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 51. animationTrace switch statement Execute this lineswitch case case case }(ch) 'a': 'b': 'c':{ System.out.println(ch); System.out.println(ch); System.out.println(ch);51Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 52. animationTrace switch statement Execute next statementswitch case case case }(ch) 'a': 'b': 'c':{ System.out.println(ch); System.out.println(ch); System.out.println(ch);Next statement;52Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 53. animationTrace switch statementSuppose ch is 'a':switch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break; case 'c': System.out.println(ch); }53Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 54. animationTrace switch statement ch is 'a':switch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break; case 'c': System.out.println(ch); }54Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 55. animationTrace switch statement Execute this lineswitch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break; case 'c': System.out.println(ch); }55Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 56. animationTrace switch statement Execute this lineswitch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break; case 'c': System.out.println(ch); }56Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 57. animationTrace switch statement Execute next statementswitch (ch) { case 'a': System.out.println(ch); break; case 'b': System.out.println(ch); break; case 'c': System.out.println(ch); } Next statement;57Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 58. 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 operator58Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 59. 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”);59Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 60. Conditional Operator, cont. (boolean-expression) ? exp1 : exp260Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 61. 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.61Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 62. Frequently-Used Specifiers Specifier OutputExample%ba boolean valuetrue or false%ca character'a'%da decimal integer200%fa floating-point number45.460000%ea number in standard scientific notation4.556000e+01%sa string"Java is cool"int count = 5; items double amount = 45.56; System.out.printf("count is %d and amount is %f", count, amount);displaycount is 5 and amount is 45.56000062Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 63. Operator Precedence var++, var-+, - (Unary plus and minus), ++var,--var (type) Casting ! (Not) *, /, % (Multiplication, division, and remainder) +, - (Binary addition and subtraction) = (Comparison) ==, !=; (Equality) ^ (Exclusive OR) && (Conditional AND) Short-circuit AND || (Conditional OR) Short-circuit OR =, +=, -=, *=, /=, %= (Assignment operator)63Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 64. 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.64Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 65. 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 leftassociative. 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)) 65Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 66. Example Applying the operator precedence and associativity rule, the expression 3 + 4 * 4 > 5 * (4 + 3) - 1 is evaluated as follows: 3 + 4 * 4 > 5 * (4 + 3) - 1 3 + 4 * 4 > 5 * 7 – 1 3 + 16 > 5 * 7 – 1(1) inside parentheses first (2) multiplication (3) multiplication3 + 16 > 35 – 1 19 > 35 – 1 19 > 34 false(4) addition (5) subtraction (6) greater than66Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 67. Companion WebsiteOperand Evaluation OrderSupplement III.A, “Advanced discussions on how an expression is evaluated in the JVM.”67Liang, 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");68Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807 69. Problem: Guessing Birth Date The program can guess your birth date. Run to see how it works. = 19 +1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 Set12 10 18 263 11 19 276 14 22 30Set27 15 23 314 5 6 7 12 13 14 15 20 21 22 23 28 29 30 318 9 10 11 12 13 14 15 24 25 26 27 28 29 30 31Set3Set416 20 24 2817 21 25 2918 22 26 3019 23 27 31Set5RunGuessBirthDateUsingConfirmationDialog 69Liang, Introduction to Java Programming, Eighth Edition, (c) 2011 Pearson Education, Inc. All rights reserved. 0132130807