How do I update Oracle Java 7 (JDK and JRE)

You can use the WebUpd8 Java PPA, so you get updates automatically through the package manager.

sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java7-installer
sudo update-java-alternatives -s java-7-oracle

• Are PPA's safe to add to my system and what are some "red flags" to watch out for?

If you need the latest Oracle Java 6, you install it too:

sudo apt-get install oracle-java6-installer

If you need the latest Oracle Java 8, you install it too:

sudo apt-get install oracle-java8-installer

If you want test Oracle Java 9 early access builds, you can install it too:

sudo apt-get install oracle-java9-installer

To switch between different Java versions, you could use the following terminal command:

sudo update-alternatives --config java

Source:

• Web Upd8: Install Oracle Java 7 in Ubuntu via PPA Repository
• Web Upd8: Oracle Releases Critical Security Update For Java 7 (7U13) And Java 6 (6U39), PPA Updated
• Web Upd8: Install Oracle Java 8 In Ubuntu Via PPA [JDK8]
• Web Upd8: Oracle Java 8 (Stable) Released, Install it In Ubuntu
• Web Upd8: Install Oracle Java 9 In Ubuntu, Linux Mint Or Debian Via PPA Repository [JDK9]