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OBJECTS

README.md

FUNCTIONS

BASICS

Comparable : (interface)

.compareTo(Object obj) : returns -1 if caller < obj, 0 =, 1 >

  • Object
    .getClass() :
    .hashCode() :
    .toString() : class to string

ERRORS

new SomeException() : returns error
new SomeException(String s) : returns error with string s

TYPES

Arrays

.asList(array) : array to list (collection)

Array

.length :

Double

.parseDouble(string) : converts from string to double

Integer

int .compareTo(Integer) : compare values
.parseInt(string) : converts from string to int
.valueOf(int) :

String

.length() :
.substring() :
.toLowerCase() :
.toUpperCase() :

INPUT/OUTPUT

BufferedReader :
InputStreamReader isr = new InputStreamReader(System.in) :
BufferedReader br = new BufferedReader(isr) :
String br.readLine() :

Scanner

// import java.util.Scanner;
// Scanner s = new Scanner(System.in);
s.next() : return input string
s.nextByte() :
s.nextDouble() :
s.nextFloat() :
s.nextInt() :
s.nextLong() :

System

.currentTimeMillis() : current time (ms)

System.out

//std output
System.out.println(string / object) : prints argument and line separator

  • if object: calls objectType.toString()

TIME

System.currentTimeMillis() :

Calendar

// import java.util.Calendar;
int DAY_OF_MONTH : value for get/set
int MONTH : value for get/set
int YEAR : value for get/set

int get(int field) :

Data

// import java.util.Date;

GregorianCalendar

// import java.util.GregorianCalendar;
//extends Calendar
GregorianCalendar(int year, int month, int dayOfMonth) : constructor

Year

// import java.time.Year;
int .getValue() : year to int

  • //es.: int y = Year.now().getValue()

static Year Year.now() : current year
Year Year.of(int ) : year from int to Year

MATH

// Math
// import java.lang.Math;
max(int a, int b) :
min(int a, int b) :