Date in PHP object orientation?

Question

I’m starting to learn Object Orientation, I’d like to know how to use date with php, because in Java you can import the java util, but in the php I don’t know how to do it, I’ll show you my code:

<?php

abstract class DadosPessoais {
protected $nome, $funcao, $rg, $cpf, $data_adm, $login, $senha;


abstract function logar();  



function getNome() {
    return $this->nome;
}

function getFuncao() {
    return $this->funcao;
}

function getRg() {
    return $this->rg;
}

function getCpf() {
    return $this->cpf;
}

function getData_adm() {
    return $this->data_adm;
}

function getLogin() {
    return $this->login;
}

function getSenha() {
    return $this->senha;
}

function setNome($nome) {
    $this->nome = $nome;
}

function setFuncao($funcao) {
    $this->funcao = $funcao;
}

function setRg($rg) {
    $this->rg = $rg;
}

function setCpf($cpf) {
    $this->cpf = $cpf;
}

function setData_adm($data_adm) {
    $this->data_adm = new DateTime($data_adm);        
}

function setLogin($login) {
    $this->login = $login;
}

function setSenha($senha) {
    $this->senha = $senha;
}
}