Java Reference

String Class

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

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(String other)
Returns true if this 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 Class

Integer(int value)
Constructs a new Integer object that represents the 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 Class

Double(double value)
Constructs a new Double object that represents the specified double value

double doubleValue()
Returns the value of this Double as a double

Math Class

static int abs(int x)
Returns the absolute value of an int value

static double abs(double x)
Returns the absolute value of a double value

static double pow(double base, double exponent)
Returns the value of the first parameter raised to the power of the second parameter

static double sqrt(double x)
Returns the positive square root of a double value

static double random()
Returns a double value greater than or equal to 0.0 and less than 1.0

ArrayList Class

int size()
Returns the number of elements in the list

boolean add(E obj)
Appends obj to end of list; returns true

void add(int index, E obj)
Inserts obj at position index (0 <= index <= size),
moving elements at position index and higher to the right (adds 1 to their indices)
and adds 1 to size

E get(int index)
Returns the element at position index in the list

E set(int index, E obj)
Replaces the element at position index with obj;
returns the element

E remove(int index)
Removes element from position index,
moving elements at position index + 1 and higher to the left (subtracts 1 from their indices)
and subtracts 1 from size;
returns the element formerly at position index

Object Class

boolean equals(Object other)

String toString()