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| <h1 class="title topictitle1">FROM Clause</h1> |
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| <div class="body refbody"><p class="shortdesc"/> |
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| <div class="section"><h2 class="title sectiontitle">Specify the class</h2> |
| |
| <p class="p"> |
| The FROM clause defines the classes on which to operate. |
| Specify the class by one of the following means: |
| </p> |
| |
| <strong class="ph b">by class name:</strong> |
| <pre class="pre codeblock">SELECT * FROM java.lang.String</pre> |
| |
| <strong class="ph b">by a regular expression matching the class name:</strong> |
| <pre class="pre codeblock">SELECT * FROM "java\.lang\..*"</pre> |
| |
| <strong class="ph b">by the object address of the class:</strong> |
| <pre class="pre codeblock">SELECT * FROM 0x2b7468c8</pre> |
| |
| <strong class="ph b">by the object addresses of more than one class:</strong> |
| <pre class="pre codeblock">SELECT * FROM 0x2b7468c8,0x2b74aee0</pre> |
| |
| <strong class="ph b">by the object id of the class:</strong> |
| <pre class="pre codeblock">SELECT * FROM 20815</pre> |
| |
| <strong class="ph b">by the object ids of more than one class:</strong> |
| <pre class="pre codeblock">SELECT * FROM 20815,20975</pre> |
| |
| <strong class="ph b">by a sub select:</strong> |
| <pre class="pre codeblock">SELECT * FROM ( SELECT * |
| FROM java.lang.Class c |
| WHERE c implements org.eclipse.mat.snapshot.model.IClass )</pre> |
| |
| <p class="p"> |
| The statement returns all objects in the heap. The |
| <span class="keyword cmdname">implements</span> |
| check is necessary, as the heap dump can contain |
| <span class="keyword cmdname">java.lang.Class</span> |
| instances caused by proxy classes or classes representing |
| primitive types such as |
| <span class="keyword cmdname">int.class</span> or <span class="keyword cmdname">Integer.TYPE</span>. |
| The following query has |
| the same effect, which calls a method directly on |
| the ISnapshot object: |
| </p> |
| |
| <pre class="pre codeblock">SELECT * FROM ${snapshot}.getClasses()</pre> |
| |
| </div> |
| |
| <div class="section"><h2 class="title sectiontitle">Include sub classes</h2> |
| |
| <p class="p"> |
| Use the |
| <span class="keyword cmdname">INSTANCEOF</span> |
| keyword to include objects of sub-classes into the |
| query: |
| </p> |
| |
| <pre class="pre codeblock">SELECT * FROM INSTANCEOF java.lang.ref.Reference</pre> |
| |
| <p class="p"> |
| The resulting table contains, amongst others, |
| WeakReference and SoftReference objects because both |
| classes extend from |
| <span class="keyword cmdname">java.lang.ref.Reference</span> |
| . By the way, the same result has the following query |
| </p> |
| |
| <pre class="pre codeblock">SELECT * FROM ${snapshot}.getClassesByName("java.lang.ref.Reference", true)</pre> |
| |
| </div> |
| |
| <div class="section"><h2 class="title sectiontitle"> |
| Prevent interpretation of the from term as classes |
| </h2> |
| |
| <p class="p"> |
| Use the OBJECTS keyword if you do not want to process |
| the term as classes. |
| Specify the object or objects by one of the following means: |
| </p> |
| |
| <strong class="ph b">by class name:</strong> |
| <pre class="pre codeblock">SELECT * FROM OBJECTS java.lang.String</pre> |
| |
| <p class="p"> |
| The result is just one object, the java.lang.String |
| class object. |
| </p> |
| |
| <strong class="ph b">by the object address of the particular object:</strong> |
| <pre class="pre codeblock">SELECT * FROM OBJECTS 0x2b7468c8</pre> |
| |
| <strong class="ph b">by the object addresses of particular objects:</strong> |
| <pre class="pre codeblock">SELECT * FROM OBJECTS 0x2b7468c8,0x2b746868</pre> |
| |
| <strong class="ph b">by the object id of the particular object:</strong> |
| <pre class="pre codeblock">SELECT * FROM OBJECTS 20815</pre> |
| |
| <strong class="ph b">by the object ids of particular objects:</strong> |
| <pre class="pre codeblock">SELECT * FROM OBJECTS 20815,20814</pre> |
| |
| <strong class="ph b">by a sub expression (Memory Analyzer 1.4 or later):</strong> |
| <pre class="pre codeblock">SELECT * FROM OBJECTS (1 + ${snapshot}.GCRoots.length)</pre> |
| |
| <div class="note note"><span class="notetitle">Note:</span> |
| Please note, that currently the FROM OBJECTS term is in |
| the test phase! |
| </div> |
| |
| </div> |
| |
| <div class="section"><h2 class="title sectiontitle"> |
| Autocompletion |
| </h2> |
| |
| <p class="p"> |
| The OQL pane now has autocompletion for class names, class name regular expressions, |
| field names, attributes and methods. |
| See <a class="xref" href="tipsandtricks.html#oqlcompletion">OQL autocompletion</a>. |
| </p> |
| |
| </div> |
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| </div> |
| |
| <div class="related-links"> |
| <div class="familylinks"> |
| <div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../reference/oqlsyntax.html">OQL Syntax</a></div> |
| </div> |
| </div> |
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