Adding a new JRE definition

You can add any number of JRE definitions.

From the menu bar, select Window > Preferences.
In the left pane, expand the Java category and select Installed JREs.
Click the Add... button. The Add JRE page opens.
In the JRE type field, select the type of JRE you want to add from the drop-down list.
In the JRE name field, type a name for the new JRE definition. All JREs of the same type must have a unique name.
In the JRE home directory field, type or click Browse to select the path to the root directory of the JRE installation (usually the directory containing the bin and lib directories for the JRE). This location is checked automatically to make sure it is a valid path.
In the Javadoc URL field, type or click Browse to select the URL location. The location is used by the Javadoc export wizard as a default value and by the 'Open External Javadoc' action.
If you want to use the default libraries and source files for this JRE, select the Use default system libraries check box. Otherwise, clear it and customize as desired. Source can be attached for the referenced JARs as well.
Click OK when you are done.