Heap walker - Classes

Heap walker - Classes

The heap walker classes view conforms to the basic layout of all heap walker views. Also see the help on key concepts for the entire heap walker.

The functionality of the classes view is identical to that of the all objects view and the recorded objects view except that it is static with respect to the current snapshot and only instances of classes and arrays in the current object set are shown.
If you have multiple classes with the same name from different classloaders and want to differentiate between those classes, you have to navigate to a specific instance, go to the data view of the heap walker and continue with the class selection as described there.

No specific view settings apply to the classes view.

The classes view has an aggregation level selector. It allows you to switch between
- classes
  Every row in the table is a single class. This is the default aggregation level.
- packages
  Every row in the table is a single package. Sub-packages are not included. In this aggregation level, the table becomes a tree table. You can open each package by clicking on the tree node on its left and see the contained classes directly beneath it.
- J2EE components
  Every row in the table is a J2EE component. This aggregation level is like a filter for the classes mode and enables you to quickly check the loaded J2EE components in your profiled application.

There are three columns shown in the table, which can be sorted.
- Name
  Depending on the aggregation level, this column shows different values:
  - classes
    shows the name of the class or the array type. The notation <class>[] stands for non-primitive arrays of any class type. (e.g. the array might be of type String[] or Object[]). A further distinction is not possible due to the nature of Java bytecode.
  - package
    shows the name of the package.
  - J2EE
    shows the display name of the J2EE component. If the display name is different from the actual class name, the class name is displayed in square brackets.
- Instance count
  Shows how many instances are currently allocated on the heap. This instance count is displayed graphically as well.
- Size
  Shows the total size of all allocated instances. Note that this is the shallow size which does not include the size of referenced arrays and instances but only the size of the corresponding pointers. The size is in bytes and includes only the object data, it does not include internal JVM structures for the class, nor does it include class data or local variables.

To add a selection step from this view you can
- select one or multiple rows from the table and click the [Use selected] button above the table.
- double click on a row in the table.
A new object set will be created that contains only the instances of the selected classes or packages. After your selection, the view helper dialog will assist you in choosing the appropriate view for the new object set.