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Like all high-level programming languages, Java provides _ :statements that let you choose actions with alternative courses.

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selection statements

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_ use conditions that are Boolean expressions. A Boolean expression is an expression that evaluates to a Boolean value: true or false. We now introduce Boolean types and relational operators

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Selection statements

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How do you compare two values, such as whether a radius is greater than 0, equal to 0, or less than 0? Java provides __ operators (also known as _ operators), shown in Table 3.1, which can be used to compare two values

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six relational, comparison

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less than or equal to (as relational operator)

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<=

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equal to (as relational operator)

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==

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not equal to (as relational operator)

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!=

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The _ testing operator is two equal signs (==), not a single equal sign (=). The latter symbol is for _.

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equality, assignment

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double radius = 1; System.out.println(radius > 0); this displays:

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true

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A variable that holds a Boolean value is known as a

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Boolean variable

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A variable that holds a Boolean value is known as a Boolean variable. The boolean _ is used to declare Boolean variables.

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data type

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assign true to lightsOn

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boolean lightsOn = true;

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True and false are _, just like a number such as 10. They are treated as reserved words and cannot be used as identifiers in the program.

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literals

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An _ is a construct that enables a program to specify alternative paths of execution.

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if statement

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Java has several types of selection statements: _ if statements, _ if-else statements, _ statements, _ if-else statements, _ statements, and _ expressions.

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one-way, two-way, nested if, multi-way, switch, conditional expressions

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A one-way if statement executes an action if and only if the condition is true. The syntax for a one-way if statement is:

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if (boolean-expression) { statement; }

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The block braces can be omitted if they enclose a _. For example, the following statements are equivalent. if (i > 0) System.out.println("i is positive");

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single statement

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(1) If the number is a multiple of 5, the program displays HiFive. If the number is divisible by 2, it displays HiEven. (Just write if statement)

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if (number % 5 == 0)

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An _ statement decides the execution path based on whether the condition is true or false.

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if-else

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The inner if statement is said to be _ inside the outer if statement.

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nested

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style, called _, avoids deep indentation and makes the program easy to read

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multi-way if-else statements

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The following errors are common among new programmers. Common Error 1: forgetting _

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Forgetting Braces

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Common Error 2: Wrong Semicolon at the

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if Line

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if (radius >= 0); same as if (radius >= 0) { } What type of error is this?

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empty block

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if (radius >= 0); same as if (radius >= 0) { }. This mistake is hard to find, because it is neither a compile error nor a runtime error; it is a _.

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logic error

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Common Error 3: Redundant Testing of

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Boolean Values

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if (even == true) is redundant. Better:

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if (even)

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if (even = true) is wrong but even so, won't show a _ error. Should be:

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compile, ==

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Common Error 4: __ Ambiguity

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Dangling else

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Common Error 5: _of Two Floating-Point Values

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Equality Test

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double x = 1.0 - 0.1 - 0.1 - 0.1 - 0.1 - 0.1; System.out.println(x == 0.5); Here, x is not exactly 0.5, but is 0.5000000000000001. You cannot reliably test equality of two _ values.

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floating-point

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you can compare whether they are close enough by testing whether the difference of the two numbers is less than some threshold. That is, two numbers x and y are very close if |x?y| ; e for a very small value, e. e, a Greek letter pronounced _, is commonly used to denote a very small value

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epsilon

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Normally, you set e to _for comparing two values of the double type and to _ for float

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1E-14, 1E-7

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setup the EPSILON variable for a floating variable

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final double EPSILON = 1E-14;

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if statement to check whether 0.5000000000000001 (x) is approximately 0.5

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if (Math.abs(x - 0.5) ; EPSILON)

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delete

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d

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The _ method can be used to return the absolute value of a

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Math.abs(a)

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improve: Often, new programmers write the code that assigns a test condition to a boolean variable like the code in (a): if (number % 2 == 0) even = true; else even = false;

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boolean even = number % 2 == 0;

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You can use _ to obtain a random double value between 0.0 and 1.0, excluding 1.0.

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Math.random()

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The previous programs generate random numbers using System.currentTimeMillis(). A better approach is to use the random() _ in the Math _.

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method, class

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A better approach is to use the random() method in the Math class. Invoking this method returns a random value of the type _.

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double

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_ returns a random single-digit integer (i.e., a number between 0 and 9).

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(int)(Math.random() * 10)

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// 1. Generate a random single-digit integer, number1 between 1-10

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int number1 = (int)(Math.random() * 10);

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// If number1 ; number2, swap number1 with number2. First line in program (ignoring setup parameters)

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if (number1 ; number2) {

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// If number1 ; number2, swap number1 with number2 line 2

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int temp = number1;

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// If number1 ; number2, swap number1 with number2 line 3

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number1 = number2;

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// If number1 ; number2, swap number1 with number2 line 4 (Swap)

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number2 = temp;

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// If number1 ; number2, swap number1 with number2 line 5: the closing line

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}

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_ (line 53) is defined in the System class. Invoking this method terminates the program. The status 0 indicates that the program is terminated normally. A nonzero status code indicates abnormal termination.

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System.exit(status)

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System.exit(status) (line 53) is defined in the System class. Invoking this method terminates the program. The status 0 indicates that the program is terminated _.

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normally

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System.exit(status) (line 53) is defined in the System class. Invoking this method terminates the program. A _ status code indicates abnormal termination.

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nonzero

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An initial value of 0 is assigned to tax (line 20). A _ error would occur if it had no initial value, because all of the other statements that assign values to tax are within the if statement. The compiler thinks that these statements may not be executed and therefore reports a compile error.

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compile

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For all programs, you should write a small amount of code and test it before moving on to add more code. This is called _ development and testing

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incremental

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_ operators, also known as Boolean operators, operate on Boolean values to create a new Boolean value.

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Logical

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the __ operator, which negates true to false and false to true.

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not (!)

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The __ of two Boolean operands is true if and only if both operands are true

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and (;;)

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The __ of two Boolean operands is true if at least one of the operands is true

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or (||)

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The __ of two Boolean operands is true if and only if the two operands have different Boolean values

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exclusive or (^)

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Note that p1 ^ p2 is the same as _

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p1 != p2

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!

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logical negation

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;;

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logical conjunction

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||

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logical disjunction

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^

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logical exclusion

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Example (assume age = 24, weight = 140) is false, because (age ; 18) is _.

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!(age ; 18), true

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_ is true, because (weight == 150) is false.

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!(weight == 150)

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(age ; 18) _ (weight ;= 140) is true, because (age ; 18) and (weight ;= 140) are both true

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;;

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(age ; 34) _ (weight ;= 150) is false, because (age ; 34) and (weight ;= 150) are both false

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||

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(age ; 18) _ (weight 18) is true.

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|| (or operator)

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(age ; 34) ^ (weight ; 140) is _, because (age ; 34) and (weight ; 140) are both false.

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false

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(age ; 34) ^ (weight ;= 140) is _, because (age ; 34) is false but (weight ;= 140) is true

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true

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if (number % 2 == 0 || number % 3 == 0) System.out.println(number + "__"); ;;;

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is divisible by 2 or 3

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if (number % 2 == 0 ^ number % 3 == 0) System.out.println(number + "is __");

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divisible by 2 or 3 but not both

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1 ;= no ;= 31 should be

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(1 ;= no) ;; (no ;= 31)

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In mathematics, the expression 1 ;= numberOfDaysInAMonth ;= 31 is correct. However, it is incorrect in Java, because 1 ;= numberOfDaysInAMonth is evaluated to a __, which cannot be compared with 31.

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boolean value

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_'s law, named after Indian-born British mathematician and logician can be used to simplify Boolean expressions. The law states: !(condition1 && condition2) is the same as !condition1 || !condition2 !(condition1 || condition2) is the same as !condition1 && !condition2

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De Morgan

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!(number == 2 || number == 3) is better written as

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number != 2 && number != 3

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In programming language terminology, && and || are known as the _ or _ operators

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short-circuit, lazy

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A year is a leap year if it is divisible by 4 but not by 100, or if it is divisible by 400. Collect the input for year:

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int year = input.nextInt();

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Generate a lottery number (0-100) & call the variable lottery

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int lottery = (int)(Math.random() * 100);

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enter a guess of lottery number

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int guess = input.nextInt();

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A _ statement executes statements based on the value of a variable or an expression.

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switch

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Here is the full syntax for the switch statement: switch (switch-expression) { case value1: statement(s)1; ___; ...

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break

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Here is the full syntax for the switch statement: switch (switch-expression) { ___ statement(s)1; break; case value2: statement(s)2; break; ... case valueN: statement(s)N; break; default: statement(s)-for-default; }

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case value1:

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Here is the full syntax for the switch statement: switch (switch-expression) { case value1: statement(s)1; break; case value2: statement(s)2; break; ... case valueN: statement(s)N; break; __ }

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default: statement(s)-for-default;

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Here is the full syntax for the switch statement: ____ case value1: statement(s)1; break; case value2: statement(s)2; break; ... case valueN: statement(s)N; break; default: statement(s)-for-default; }

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switch (switch-expression) {

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The value1, . . ., and valueN must have the same __ as the value of the switchexpression. Value1, . . ., & valueN are ___ expressions, meaning that they cannot contain variables, such as 1 + x.

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data type, constant

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When the value in a case statement matches the value of the switch-expression, the statements starting from this case are executed until either a _ _ or the end of the switch statement is reached

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break statement

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The _ which is optional, can be used to perform actions when none of the specified cases matches the _.

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default case, switch-expression

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The _ case, which is _, can be used to perform actions when none of the specified cases matches the switch-expression

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default, optional

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The keyword break is _. The break statement immediately ends the switch statement.

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optional

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Do not forget to use a break statement when one is needed. Once a case is matched, the statements starting from the matched case are executed until a _ statement or the __ statement is reached

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break, end of the switch

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Do not forget to use a break statement when one is needed. Once a case is matched, the statements starting from the matched case are executed until a break statement or the end of the switch statement is reached. This is referred to as _.

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fall-through behavior

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To avoid programming errors and improve code maintainability, it is a good idea to put a _ in a case clause if break is purposely omitted.

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comment

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A __ evaluates an expression based on a condition

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conditional expression

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if (x > 0) y = 1; else y = -1; Alternatively, as in the following example, you can use a conditional expression to achieve the same result.

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y = (x > 0) ? 1 : -1;

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Conditional expressions are in a completely different style, with no explicit if in the statement. The syntax is:

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boolean-expression ? expression1 : expression2;

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Suppose you want to assign the larger number of variable num1 and num2 to max. You can simply write a statement using the conditional expression:

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max = (num1 > num2) ? num1 : num2;

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The symbols ? and : appear together in a conditional expression. They form a _ and also called a _ operator because it uses three operands.

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conditional operator, ternary (It is the only ternary operator in Java.)

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Operator _ and _ determine the order in which operators are evaluated.

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precedence, associativity

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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 __.

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left associative

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Assignment operators are right associative. Therefore, the expression a = b += c = 5 is equivalent to

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a = (b += (c = 5))

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Finding logic errors, on the other hand, can be very challenging. Logic errors are called _. The process of finding and correcting errors is called debugging

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bugs

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A common approach to debugging is to use a combination of methods to help pinpoint the part of the program where the bug is located. You can _ the program (i.e., catch errors by reading the program), or you can insert print statements in order to show the values of the variables or the execution flow of the program.

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hand-trace

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JDK includes a command-line debugger, _, which is invoked with a class name. _ is itself a Java program, running its own copy of Java .

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jdb, interpreter

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__: The debugger lets you trace all of the method calls. This feature is helpful when you need to see a large picture of the program-execution flow.

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Displaying call stacks

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