eclipse

错误提示：

A Java Runtime Environment (JRE) or Java Development Kit (JDK)
must be available in order to run Eclipse. No Java virtual machine
was found after searching the following locations:
/opt/eclipse/jre/bin/java
java in your current PATH

先检查

ls /usr/lib/jvm # 检查是否解压缩

保证环境变量正确配置

cd ~
vim ~/.bashrc #vim不行那就vi

在这个文件的开头位置，添加如下几行内容：

export JAVA_HOME=/usr/lib/jvm/jdk1.8.0_162
export JRE_HOME=${JAVA_HOME}/jre
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
export PATH=${JAVA_HOME}/bin:$PATH

source ~/.bashrc

java -version

正常输出

但如果这样设置了，运行eclipse时依然报错

A Java Runtime Environment (JRE) or Java Development Kit (JDK)
must be available in order to run Eclipse. No Java virtual machine
was found after searching the following locations:
/opt/eclipse/jre/bin/java
java in your current PATH

则需要手动设置eclipse安装目录下的/eclipse/eclipse.ini

sudo gedit /opt/eclipse/eclipse.ini

在-vmargs这一行之前添加以下两行内容：

-vm
/usr/lib/jvm/jdk1.8.0_162/bin/java

保存并重新启动eclipse

Hadoop

dblab@dblab-Vmware:/usr/local/hadoop$ ./sbin/start-dfs.sh
Starting namenodes on [localhost]
localhost: ERROR: JAVA_HOME is not set and could not be found.
Starting datanodes
localhost: ERROR: JAVA_HOME is not set and could not be found.
Starting secondary namenodes [dblab-Vmware]
dblab-Vmware: ERROR: JAVA_HOME is not set and could not be found.

首先保证环境变量正确设置，看上一段即可，这里不再赘述

解决办法：

• 找到 Hadoop 的配置文件目录：
  • 一般位于 $HADOOP_HOME/etc/hadoop 目录下，进入该目录，找到 hadoop-env.sh 文件。
• 编辑 hadoop-env.sh 文件：
  • 使用文本编辑器打开 hadoop-env.sh 文件，在文件中查找 JAVA_HOME 的设置部分，通常会有类似这样的注释引导你去设置：

# The java implementation to use.
# export JAVA_HOME=${JAVA_HOME}

可以去掉注释，并将其修改为你实际的 Java 安装路径，如下：

export JAVA_HOME=/usr/lib/jvm/jdk1.8.0_162