[转]centos7 安装jdk11 并设置默认java版本

https://www.server-world.info/en/note?os=CentOS_7&p=jdk11&f=2

OpenJDK 11 : Install

2018/10/17

	Install OpenJDK 11 to configure Java development environment.
[1]	Install OpenJDK 11. Make sure the latest version and source URL of JDK on download site. ⇒ http://jdk.java.net/11/

[root@dlp ~]#

curl -O https://download.java.net/java/GA/jdk11/13/GPL/openjdk-11.0.1_linux-x64_bin.tar.gz

[root@dlp ~]#

tar zxvf openjdk-11.0.1_linux-x64_bin.tar.gz

[root@dlp ~]#

mv jdk-11.0.1 /usr/local/

[root@dlp ~]#

vi /etc/profile.d/jdk11.sh

# create new

export JAVA_HOME=/usr/local/jdk-11.0.1
export PATH=$PATH:$JAVA_HOME/bin

[root@dlp ~]#

source /etc/profile.d/jdk11.sh

[root@dlp ~]#

java -version

openjdk version "11.0.1" 2018-10-16
OpenJDK Runtime Environment 18.9 (build 11.0.1+13)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.1+13, mixed mode)

[2]	If another version of JDK had been installed, change the default like follows.

[root@dlp ~]#

alternatives --config java

There is 1 program that provides 'java'.

  Selection    Command
-----------------------------------------------
*+ 1           java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.181-3.b13.el7_5.x86_64/jre/bin/java)

[root@dlp ~]#

alternatives --install /usr/bin/java java $JAVA_HOME/bin/java 2

[root@dlp ~]#

alternatives --config java

There are 2 programs which provide 'java'.

  Selection    Command
-----------------------------------------------
*+ 1           java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.181-3.b13.el7_5.x86_64/jre/bin/java)
   2           /usr/local/jdk-11.0.1/bin/java

Enter to keep the current selection[+], or type selection number: 2

[3]	Create a test program and make sure if it works normally.

[root@dlp ~]#

vi day.java

import java.util.Calendar;

class day {
    public static void main(String[] args) {
        Calendar cal = Calendar.getInstance();
        int year = cal.get(Calendar.YEAR);
        int month = cal.get(Calendar.MONTH) + 1;
        int day = cal.get(Calendar.DATE);
        int hour = cal.get(Calendar.HOUR_OF_DAY);
        int minute = cal.get(Calendar.MINUTE);
        System.out.println(year + "/" + month + "/" + day + " " + hour + ":" + minute);
    }
}

# possible to run java file

[root@dlp ~]#

java day.java

2018/10/16 19:48

# also possible to run after compile

[root@dlp ~]#

javac day.java

[root@dlp ~]#

java day

2018/10/16 19:50