APCSA Unit 1 Test Review (1.7-1.15)

class

defines a new data type. It is the formal implementation, or blueprint, of the attributes and behaviors of the objects of that class

object

a specific instance of a class with defined attributes. _____ are declared as variables of a class type

constructors

code that is used to create new objects and initialize the object’s attributes

new

keyword used to create objects with a call to one of the class’s constructors

instance variables

define attributes for objects; typically private

(instance) methods

define the behaviors or functions for objects

static methods

methods that belong to the class itself rather than to any specific instance/object of the class

dot (.) operator

used to access an object’s methods

parameters (arguments)

the values or data passed to an object’s method inside the parentheses in the method call to help the method do its job

return values

values returned by methods to do the calling method

immutable

String methods do not change the String object. Any method that seems to change a string actually creates a new string

new

is used to create a new object

null

is used to indicate that an object reference doesn’t refer to any object yet

String(String str)

Constructs a new String object that represents the same sequences of characters as str

int length()

returns the number of characters in a String object

String substring(int from, int to)

returns the substring beginning at index from and ending at index (to-1). The single element substring at position index can be created by calling substring(index, index+1)

String substring(int from)

returns substring(from, length())

int indexOf(String str)

returns the index of the first occurrence of str; returns -1 if not found

boolean equals(Object other)

returns true if this (the calling object) is equal to other; returns false otherwise

int compareTo(String other)

returns a value < 0 if this is less than other; returns zero if this is equal to other; returns a value > 0 if this is greater than other.

Integer(value)

Constructs a new integer object that represents a specified int value

Integer.MIN_VALUE

The minimum value represented by an int or integer

Integer.MAX_VALUE

The maximum value represented by an int or integer

Int IntValue()

Returns the value of this Integer as an int

Double(double value)

Constructs a new Double object and represents that specified double value

double doubleValue()

Returns the value of this Double as a double

int abs(int)

Returns the absolute value of an int value (which means no negatives)

double abs(double)

returns the absolute value of a double value

double pow(double,double)

Returns the value of the first parameter raised to the power of the second parameterd

double sqrt(double)

Returns the positive square root of a double value

double random()

Returns a double value greater than or equal to 0.0 and less than 1.0 (not including 1.0)

(int)(Math.random()*range) + min

moves the random number into a range starting from a minimum number. The range is the (max number - min number + 1)

Example: to get a number in the range of 5 to 10, use the range 10-5 + 1 = 6 and the min number 5: (int)(Math.random()&6) + 5)

object

a specific instance of a class with defined attributes

class

defines a new data type with instance variables and methods

methods

define the behaviors or functions for objects

constructors

code that is used to create new objects and intialize the object’s attributes

parameters

the values or data passed to an object’s method