java常用的包

java.nio 

java.nio.channels

java.nio.channels.spi

java.nio.charset

java.nio.charset.spi

java.nio.file

java.nio.file.attribute

java.nio.file.spi

java.io

java.net

java.sql

java.util

java.math

java.util

java.util.concurrent

java.util.concurrent.locks

java.util.concurrent.atomic

java.util.regex

java.util.stream

java.util.spi

java.util.function

java.lang

java.lang.reflect