If an expression you evaluate causes a runtime exception, the exception will be reported in the editor. For example:
Type and select the expression Object x = null; x.toString() in the editor and click Display in the toolbar.
Object x = null; x.toString()
The error message:
An exception occurred during evaluation: java.lang.NullPointerException
will be displayed in the editor.
Java editor
Displaying the result of evaluating an expression Inspecting the result of evaluating an expression Executing an expression