请确保JAVA_HOME指向JDK而不是JRE

Question

我下载了jdk-9.0.1_linux-x64_bin。焦油gz和jre-9.0.1_linux-x64_bin。焦油来自链接的gzhttp://www.oracle.com/technetwork/java/javase/downloads/index.html.将它们提取出来，并在/usr/local/java中发布。然后编辑/etc/profile以添加

JAVA_HOME=/usr/local/java/jdk-9.0.1
JRE_HOME=/usr/local/java/jre-9.0.1
PATH=$PATH:$JRE_HOME/bin:$JAVA_HOME/bin
export JAVA_HOME
export JRE_HOME
export PATH

整个文件看起来像

# /etc/profile: system-wide .profile file for the Bourne shell (sh(1))
# and Bourne compatible shells (bash(1), ksh(1), ash(1), ...).

if [ "$PS1" ]; then
  if [ "$BASH" ] && [ "$BASH" != "/bin/sh" ]; then
    # The file bash.bashrc already sets the default PS1.
    # PS1='\h:\w\$ '
    if [ -f /etc/bash.bashrc ]; then
      . /etc/bash.bashrc
    fi
  else
    if [ "`id -u`" -eq 0 ]; then
      PS1='# '
    else
      PS1='$ '
    fi
  fi
fi

# The default umask is now handled by pam_umask.
# See pam_umask(8) and /etc/login.defs.

if [ -d /etc/profile.d ]; then
  for i in /etc/profile.d/*.sh; do
    if [ -r $i ]; then
      . $i
    fi
  done
  unset i
fi

JAVA_HOME=/usr/local/java/jdk-9.0.1
JRE_HOME=/usr/local/java/jre-9.0.1
PATH=$PATH:$JRE_HOME/bin:$JAVA_HOME/bin
export JAVA_HOME
export JRE_HOME
export PATH

然后输入以下命令

sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jdk-9.0.1/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk-9.0.1/bin/javac" 1
sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/local/java/jdk-9.0.1/bin/javaws" 1 


sudo update-alternatives --set java /usr/local/java/jdk-9.0.1/bin/java
sudo update-alternatives --set javac /usr/local/java/jdk-9.0.1/bin/javac
sudo update-alternatives --set javaws /usr/local/java/jdk-9.0.1/bin/javaws

source /etc/profile

reboot

现在java版本正在显示

java version "9.0.1"
Java(TM) SE Runtime Environment (build 9.0.1+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.1+11, mixed mode)

之后我尝试安装android Studio

我收到以下消息

./studio.sh 
Java HotSpot(TM) 64-Bit Server VM warning: Option UseConcMarkSweepGC was deprecated in version 9.0 and will likely be removed in a future release.
WARN: Unknown class loader: jdk.internal.loader.ClassLoaders$AppClassLoader
WARN: Unknown class loader: jdk.internal.loader.ClassLoaders$PlatformClassLoader
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.intellij.util.lang.UrlClassLoader (file:/home/user/Downloads/Android/android-studio/lib/util.jar) to field java.lang.ClassLoader.parallelLockMap
WARNING: Please consider reporting this to the maintainers of com.intellij.util.lang.UrlClassLoader
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

JDK Required: 'tools.jar' seems to be not in Studio classpath.
Please ensure JAVA_HOME points to JDK rather than JRE.

Answer 1

我建议您卸载JRE安装，只使用JDK安装。JDK包含JRE中的所有内容。安装两者都是浪费磁盘空间。。。并可能导致像你所经历的那样的问题。

卸载JRE时，请记住更新环境变量。

还值得注意的是，通过这样设置PATH，您正在绕过“替代”选择器。

Answer 2

尝试更改设置PATH变量的行

PATH=$PATH:$JRE_HOME/bin:$JAVA_HOME/bin

到

PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin

这将优先考虑JDK而不是JRE。