Classes

Available fields and methods and examples on how to use them

Object

Parent class of all Java objects. 

Parent

None (and itself at the same time, don't question it)

Variables and Functions

Name Type Info
toString() String Tag collection type.
equals(Object other) boolean Checks equality with another object.
hashCode() int Hash code of this object. It is used to optimize maps and other things, should never be used for object equality.
class Class Object's type/class.

String

Class of string objects, such as "abc" (and in JS 'abc' works as well) 

Parent

Object

Variables and Functions

Name Type Info
empty boolean Returns if string is empty a.k.a string === ''
toLowerCase() String Returns a copy of this string, but with all characters in upper case
toUpperCase() String Returns a copy of this string, but with all characters in lower case
equalsIgnoseCase(String other) boolean Hash code of this object. It is used to optimize maps and other things, should never be used for object equality.
length() int Number of characters
charAt(int index) char Single character at index

Primitive Types

Information

Primitive types are objects that don't have a real class and don't inherit methods from Object.

All primitive types

Type Java class Info
void Void No type
byte Byte 8 bit decimal number.
short Short 16 bit decimal number.
int Integer 32 bit decimal number, most common decimal type.
long Long 64 bit decimal number.
float Float 32 bit floating point number.
double Double 64 bit floating point number.
char Character Single character in String such as 'a' or '-'.
boolean Boolean Only true and false values. Can be checked in if function without comparing to true, as if (x) or if (!x) instead of if (x == true) or if (x == false).