Ubuntu 20.04 Java 설치

Java Install

1. apt-get 최신화

sudo apt-get update
sudo apt-get upgrade

2. Java 11 & JDK 설치

sudo apt-get install openjdk-11-jre openjdk-11-jdk

3. Java 버전 확인

java -version

openjdk version "11.0.11" 2021-04-20
OpenJDK Runtime Environment (build 11.0.11+9-Ubuntu-0ubuntu2.20.04)
OpenJDK 64-Bit Server VM (build 11.0.11+9-Ubuntu-0ubuntu2.20.04, mixed mode, sharing)

4. 환경 설정하기

vim ~/.bashrc

# ~/.bashrc
export JAVA_HOME=$(dirname $(dirname $(readlink -f $(which java))))
export PATH=$PATH:$JAVA_HOME/bin

4-1. 환경설정 적용하기

source ~/.bashrc

4-2. 적용 확인하기

$ echo $JAVA_HOME
/usr/lib/jvm/java-11-openjdk-amd64

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Java 버전 관리 (Alternatives)

PATH에 직접 등록하여도 되지만, 저는 Alternatives라는 툴을 이용하여 OpenJdk11를 관리하려고 합니다. Alternatives를 사용하면 원하는 자바의 버전을 쉽게 변경할 수 있습니다.

Alternatives를 잘 모르시면 Ubuntu에서 Python 버전을 변경하는 방법을 참고하세요.

1. Alternatives에 등록된 자바 버전 확인

$ sudo update-alternatives --config java
There are 4 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
* 0            /usr/lib/jvm/java-9-openjdk-amd64/bin/java      1101      auto mode
  1            /usr/lib/jvm/java-9-openjdk-amd64/bin/java      1101      manual mode
  2            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1081      manual mode

2. Alternatives에 추가

sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/java-11-openjdk-amd64/bin/java 1

3. 추가된 자바 확인

$ sudo update-alternatives --config java
There are 4 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
* 0            /usr/lib/jvm/java-11-openjdk-amd64/bin/java      1      auto mode
  1            /usr/lib/jvm/java-9-openjdk-amd64/bin/java      1101      manual mode
  3            /usr/lib/jvm/java-9-openjdk-amd64/bin/java      1101     manual mode
  2            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1081      manual mode

4. 변경된 것 확인

$ java --version
openjdk 11.0.9.1 2020-11-04
OpenJDK Runtime Environment (build 11.0.9.1+1-Ubuntu-0ubuntu1.20.04)
OpenJDK 64-Bit Server VM (build 11.0.9.1+1-Ubuntu-0ubuntu1.20.04, mixed mode, sharing)

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OpenJDK 삭제

1. 삭제

$ sudo apt-get purge openjdk*

2. 삭제된 것 확인

$ java --version
bash: /usr/bin/java: No such file or directory

 

 

Reference: https://codechacha.com/ko/ubuntu-install-open-jdk11/