Variable Manipulation Basics

Variable Manipulation

• blah = height + width == 43; evaluates to true because the sum of height and width is equal to 43.
• blah = !(distance > 20) || speed == 7.5; evaluates to true because distance is not greater than 20, and speed is equal to 7.5.
• blah = bird.compareTo("Sparrow") < 0; evaluates to false because bird is equal to "sparrow" (case-sensitive), which is not lexicographically less than "Sparrow."
• blah = height % 3 == 0 && width / 4 >= 7; evaluates to true because the remainder of height divided by 3 is 0, and the result of width divided by 4 is greater than or equal to 7.
• blah = dessert.indexOf('k') == 0; evaluates to false because the character k is not at index 0 of the string dessert.
• blah = speed * 2 != distance && !(width < 25); evaluates to true because speed multiplied by 2 is not equal to distance, and width is not less than 25.
• blah = height != width; evaluates to true because height is not equal to width.
• blah = fruit.equals("Mango") || dessert.length() > 5; evaluates to true because fruit is equal to "mango" (case-sensitive), which is equivalent to "Mango" (case-insensitive).
• blah = Math.pow(speed, 2) <= height; evaluates to false because the square of speed is greater than height.
• blah = Math.min(height, width) > Math.sqrt(distance); evaluates to true because the minimum value of height and width is greater than the square root of distance.

Conditional Structure Output

• When the input is the following:
  • isVerified = false;
  • duration = 2;
  • animal = "elephant";
  • the code will print:
    • H
    • K
    • L
• When the input is the following:
  • isVerified = true;
  • duration = 6;
  • animal = null;
  • The code will print:
    • B
    • D
    • I
    • L
• When the input is the following:
  • isVerified = false;
  • duration = 3;
  • animal = "";
  • The code will print:
    • A
    • D
    • L

Method Output

• When the input is the following:
  • Device dev = new Device();
  • System.out.print(dev.process(3));
  • dev.process();
  • The code will print:
    • 59
    • Device: active - basic [low]
• When the input is the following:
  • Device dev = new Device (64, "premium", false);
  • System.out.print(dev.process(10));
  • dev.process();
  • The code will print:
    • 171
    • Device: active - premium [low]
• When the input is the following:
  • Device dev = new Device("proModel");
  • System.out.print(dev.process(5));
  • dev.process();
  • The code will print:
    • 33
    • Device: active - proModel [low]
• When the input is the following:
  • Device dev = new Device (9, "simple");
  • System.out.print(dev.process(8));
  • dev.process();
  • The code will print:
    • 7
    • Device: inactive - Simple [low]

Boolean Expression Simplification

• !true || true && !false && !(true || true) simplifies to
  • false || true && true && false using De Morgan's Law for the last part of the expression
  • false || true && true && false using boolean evaluation
  • false || true && false using order of logical operations
  • false || false using order of logical operations
  • false using boolean evaluation
• !(numPets > 3 || isFunny) simplifies to:
  • !(numPets > 3) && !isFunny using De Morgan's Law
  • numPets <= 3 && !isFunny using negation of greater than
• !(isCool && gpa != 4.0) simplifies to:
  • !isCool || !(gpa != 4.0) using De Morgan's Law
  • !isCool || gpa == 4.0 using negation of not equals to

String Evaluation

• blah = word.equals(phrase.substring(0,3)); evaluates to false because word is equal to "bang", and the substring of phrase from index 0 to 3 is "ban" (not including index 3).
• blah = phrase == text; evaluates to true because phrase and text both reference the same String object in memory. However, this comparison is checking for reference equality, not value equality.
• blah = word == text; evaluates to false because word and text reference different String objects in memory.
• blah = ahh == ugh; results in an error because ahh is not initialized and therefore has no value.
• blah = text != ugh; evaluates to true because text is a valid String object, and ugh is null.
• blah = quote != null; evaluates to true because quote is a valid String object, even if it is equal to the string "null".
• blah = ugh.equals(ahh); results in an error because ahh is not initialized and therefore has no value.
• blah = word.equals(phrase); evaluates to true because word and phrase have the same value, even though they reference different objects in memory.
• blah = word.compareTo(quote) < 0; evaluates to true because quote is null, and the compareTo() method always returns 0 when compared to a null value.
• blah = word.compareTo(phrase) > 0; evaluates to false because word and phrase have the same value, so compareTo() would return 0, not a positive number.
• blah = ugh.equals(word); results in an error because ugh is null and you cannot use equals() on a null value.
• blah = word.substring(text.length()/2);
  • blah = word.equals(ugh); results in false because word is "bang" and ugh is null. The code will execute normally because word is not null and text.length() is 4, so text.length()/2 is 2.

Conditional Structure Output with Assumptions

• When the input is the following:
  • animal = null;
  • duration = 1;
  • isVerified = false;
  • the code will print:
    • A
    • D
• When the input is the following:
  • animal = null;
  • duration = 6;
  • isVerified = false;
  • The code will print:
    • C
    • D
• When the input is the following:
  • animal = null;
  • duration = 5;
  • isVerified = true;
  • The code will print:
    • B
    • D
• When the input is the following:
  • animal = "zebra";
  • duration = 6;
  • isVerified = true;
  • The code will print:
    • E
    • L
• When the input is the following:
  • animal = "cat";
  • duration = 7;
  • isVerified = true;
  • The code will print:
    • F
    • G
    • J
    • L
• When the input is the following:
  • animal = "snake";
  • duration = 6;
  • isVerified = true;
  • The code will print:
    • F
    • G
    • K
    • L

Methods

• public double computeTaxes(double income) {
  • takes as input a double value representing income which represents the individual's yearly income
  • returns a double value that represents the amount of taxes for the specific income level
• public String triangleType(double a, double b, double c) {
  • takes as input three double values representing a (length of one side of the triangle), b (length of one side of the triangle), and c (length of one side of the triangle)
  • uses the lengths of the sides to determine the type of triangle and returns a String value describing the type.

This quiz tests your understanding of variable manipulation and conditional expressions in programming. You'll evaluate different statements based on provided conditions and determine their Boolean outcomes. Prepare to tackle logical operations and string comparisons!