Instalar o JDK 7 No Ubuntu 18

Download the JDK for Linux 32-bit or 64-bit (for example: jdk-7u80-linux-x64.tar.gz)

1. Navigate to ~/Downloads:

   cd /home/"your_user_name"/Downloads
   

2. Create a a directory in /usr/local where java will reside and copy tarball there:

   sudo mkdir -p /usr/local/java
   sudo cp -r jdk-7u80-linux-x64.tar.gz /usr/local/java/
   

3. Navigate to /usr/local/java:

   cd /usr/local/java
   

4. Extract the tarball:

   sudo tar xvzf jdk-7u80-linux-x64.tar.gz
   

5. Check if tarball has been successfully extracted:

   ls –a    #you should see jdk1.7.0_80 
   

6. Open /etc/profile with sudo privileges:

   sudo nano /etc/profile
   

7. Scroll down to the end of the file using arrow keys and add the following lines below to the end of /etc/profile file:

   JAVA_HOME=/usr/local/java/jdk1.7.0_80
   JRE_HOME=/usr/local/java/jdk1.7.0_80 
   PATH=$PATH:$JRE_HOME/bin:$JAVA_HOME/bin
   
   export JAVA_HOME
   export JRE_HOME
   export PATH
   

8. Update alternatives:

   sudo update-alternatives --install "/usr/bin/java" "java" "/usr/local/java/jdk1.7.0_80/bin/java" 1
   sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/local/java/jdk1.7.0_80/bin/javac" 1
   sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/local/java/jdk1.7.0_80/bin/javaws" 1
   sudo update-alternatives --set java /usr/local/java/jdk1.7.0_80/bin/java
   sudo update-alternatives --set javac /usr/local/java/jdk1.7.0_80/bin/javac
   sudo update-alternatives --set javaws /usr/local/java/jdk1.7.0_80/bin/javaws
   

9. Reload profile:

   source /etc/profile
   

10. Verify installation:

    java -version
    

    You should receive a message which displays:

    java version "1.7.0_80"
    Java(TM) SE Runtime Environment (build 1.7.0_80-b15)
    Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)