Installing Java 7 on Ubuntu

> **Note:** This question was asked before Oracle made the OpenJDK the free version of the Oracle JDK, and the historic answers reflect that. As of 2022 you should not use Java 7 unless you must for projects which cannot run on OpenJDK 8. To install java I have always used the classic way from the terminal. I would like to install java manually. I placed the folder of the JDK on the desk and I set environment variables (PATH, CLASSPATH and JAVA_HOME). From the terminal, if I type `java -version` I get printed foralobo@ubuntu-vincy:~$ java -version java version "1.7.0_21" Java(TM) SE Runtime Environment (build 1.7.0_21-b11) Java HotSpot(TM) 64-Bit Server VM (build 23.21-b01, mixed mode) But when I try to install eclipse or netbeans, the system warns by saying that there is no java installed on the machine. What is missing to compleatare manual installation? (Ubuntu 13.04)