Java Section 4

evaluates to true only if BOTH operands are true (&&)

AND

a type that has just two values: true or false

Boolean

used next to switch statement; diff from boolean expression, can be int char or String; cannot be range of values

Controlling expression

short circuit evaluation of: operand1 && operand2

If the first operand evaluates to true, operand2 is evaluated. If the first operand evaluates to false, the result of the AND operation is always false, so operand2 is not evaluated.

short circuit evaluation: operand1 || operand2

If the first operand evaluates to true, the result of the OR operation is always true, so operand2 is not evaluated. If the first operand evaluates to false, operand2 is evaluated.

Floating-point numbers should be compared for "close enough" rather than exact equality which is written as

Math.abs(x - y) < 0.0001

evaluates to the opposite of the operand (!)

NOT

evaluates to true if ANY operand is true (||)

OR

skips evaluating later operands if the result of the logical operator can already be determined

Short circuit evaluation

a != b means that

a is not equal to b

For integral operand types such as int, & and | represent _________- operators, which perform AND or OR on corresponding individual bits of the operands

bitwise

efers to a quantity that has only two possible values, true or false

boolean

chooses between two or more possible actions - the flow of control splits into two or more possible directions

branching statement

causes execution of that switch statement to end; if left out, execution continues to the next case

break statement

in swtich statement, each case begins with "case" followed by a _______ which is then followed by a colon (:) then one or more statements

case label

in switch statement, braces enclose a set of ______: possible values of the controlling expression

cases

A ________________ has the form condition ? exprWhenTrue : exprWhenFalse. (x == 2) ? 5 : 9 * x evaluates to 5.

conditional expression

? and : together

conditional operator

statements in the ______ case are executed if no other case is matched; not required but recommended

default

The difference threshold indicating that floating-point numbers are equal is often called the

epsilon

Floating-point types should not be compared using the ________ operators, due to the imprecise representation of floating-point numbers

equality

evaluates to true if the left side and the right side are equal; appropriate for determining if two ints, booleans, or chars have the same value; should not be used to compare objects

equality operator ==

An ____________ is a detected runtime error that commonly prints an error message and terminates the program.

exception

If the range has gaps, the range's ends must be (implicitly / explicitly) indicated, using AND

explicitly

Floating-point numbers should not be compared using ==. Ex: Avoid float1 == float2. Reason: ______________

floating point values are approximations; better to specify some value such that if a and b differ by less than that, they are considered equal if (abs(a - b) < epsilon) where a, b, and epsilon are floating point types

the order in which a program performs actions

flow of control

a branch that is taken only if an expression is true

if

executes a group of statements if an expression is true

if statement

When are the statements for a case executed?

if the value of the controlling expression matches the case label of a particular case

this structure has two branches: the first branch is taken if an expression is true, else the other branch is taken

if-else

executes one group of statements when an expression is true, and another group of statements when the expression is false

if-else statement

this structure is when we want to take one of multiple (three or more) branches. each branch's expression is checked in sequence, and as soon as one branch's expression is found to be true, that branch is taken. if no expression is true, execution will reach the else branch, which then executes

ifelse-ifelse

Strings are considered ___________, meaning they cannot be changed

immutable

each string character has a position number called _, which starts at 0 and not 1

index

gets index of first item occurrence in a string, else -1. Item may be char, String variable, or string literal.

indexOf(item)

starts at index indx

indexOf(item, indx)

What is wrong with (s1 == s2)? (where s1 and s2 are strings)

is true if and only if s1 and s2 refer to the same memory location. if s1 and s2 refer to strings with identical sequences of characters, but stored in diff memory locations, (s1 == s2) is false

true if digit: 0-9.

isDigit(c)

true if alphabetic: a-z or A-Z

isLetter(c)

true if whitespace

isWhitespace(c)

finds the last occurrence of the item in a string, else -1.

lastIndexOf(item)

capital letters precede lowercase letters, normal alphabetical ordering applies; ant precedes bug, Cat precedes cat, he precedes hello

lexicographical order

treats operands as being true or false, and evaluates to true or false. they include AND, OR, and NOT

logical operators

when a branch's statements can include any valid statements, including another if-else statement

nested if-else

Omitting the break statement for a case will cause the statements within the ____________ to be executed.

next case

The order in which operators are evaluated in an expression are known as _______________ (), !, * / % + -, < <= > >=, == !=, &&, ||

precedence rules

checks how one operand's value relates to another, like being greater than

relational operator (> < <= >=)

returns a new String in which all occurrences of findChar have been replaced with replaceChar

replace(findChar, replaceChar)

returns a new String in which all occurrences of findStr have been replaced with replaceStr

replace(findStr, replaceStr)

returns a new string that appends s2 to s1

s1.concat(s2)

The method ____________ returns s1's length

s1.length()

The notation ____________ determines the character at index x of a string

someString.charAt(x)

Shorthand for str1 = str1 + str2. str1 must be a String variable, and str2 may be a String variable, a string literal, or a character.

str1 += str2

A programmer compares strings relationally using the notation __________________; returns a neg number if str1 precedes str2, zero if the two strings are equal, pos number if str2 precedes str1; useful for lexicographical order

str1.compareTo(str2)

A programmer can compare two strings using the notation ____________

str1.equals(str2)

A programmer can compare strings while ignoring case using _______________ and _______________

str1.equalsIgnoreCase(str2) str1.compareToIgnoreCase(str2)

The relational and equality operators work for integer, character, and floating-point built-in types. The operators should not be used with _______

strings

returns substring starting at startIndex and ending at endIndex - 1

substring(startIndex, endIndex)

represents multi-branch behavior involving a variable being compared to constant values. the program executes the first case whose constant expression matches the value of the switch expression, executes that case's statements, and then jumps to the end. if no cases match, then the default case statements are executed; should be an integer, char, or string, should not be a Boolean or a floating-point type.

switch statement

an operator that takes three arguments

ternary operator

character operation - Lowercase version

toLowerCase(c)

character operation - Uppercase version

toUpperCase(c)

What do braces in an if-else statement allow programmers to do

use multiple statements / compound statements

they represent a grouping, such as a grouping of statements

{} braces

compares two strings to see if they are equal while ignoring the case of the letters

"Hello".equalsIgnoreCase("hello")

________ to the next case can be useful when multiple cases should execute the same statements

"falling through"