update JAVA from tar.gz in ubuntu

1. 下载 jdk-8u221-linux-i586.tar.gz
   2.解压
   tar -zxvf jdk-8u221-linux-i586.tar.gz

2. 删除原来的JAVA， 将解压好的文件拷贝到usr/lib下
   sudo rm -rf /usr/lib/jvm
cd ~
sudo mv jdk1.8.0_171 /usr/lib/jvm

更新ubuntu 的默认设置
sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/bin/java 300
sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/bin/javac 300
sudo update-alternatives --config java
sudo update-alternatives --config javac

检查java版本，输入：

java version "1.8.0_221"
Java(TM) SE Runtime Environment (build 1.8.0_221-b11)
Java HotSpot(TM) Server VM (build 25.221-b11, mixed mode)```