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Also rename variable from ma to mc
This is slightly less confusing, given the type name is now `MethodCall`.
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‎docs/codeql/codeql-language-guides/basic-query-for-java-code.rst‎

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@@ -46,7 +46,11 @@ Running a quick query
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where
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ma.getMethod().hasName("equals") and
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ma.getArgument(0).(StringLiteral).getValue() = ""
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select ma, "This comparison to empty string is inefficient, use isEmpty() instead."
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from MethodCall mc
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where
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mc.getMethod().hasName("equals") and
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mc.getArgument(0).(StringLiteral).getValue() = ""
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select mc, "This comparison to empty string is inefficient, use isEmpty() instead."
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Note that CodeQL treats Java and Kotlin as part of the same language, so even though this query starts with ``import java``, it will work for both Java and Kotlin code.
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@@ -55,7 +59,7 @@ Running a quick query
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.. image:: ../images/codeql-for-visual-studio-code/basic-java-query-results-1.png
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:align: center
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If any matching code is found, click a link in the ``ma`` column to view the ``.equals`` expression in the code viewer.
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If any matching code is found, click a link in the ``mc`` column to view the ``.equals`` expression in the code viewer.
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.. image:: ../images/codeql-for-visual-studio-code/basic-java-query-results-2.png
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:align: center
@@ -72,15 +76,15 @@ After the initial ``import`` statement, this simple query comprises three parts
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+==================================================================================================+===================================================================================================================+===================================================================================================+
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| ``import java`` | Imports the standard CodeQL libraries for Java and Kotlin. | Every query begins with one or more ``import`` statements. |
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+--------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------+
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| ``from MethodCall ma`` | Defines the variables for the query. | We use: |
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| ``from MethodCall mc`` | Defines the variables for the query. | We use: |
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| | Declarations are of the form: | |
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| | ``<type> <variable name>`` | - a ``MethodCall`` variable for call expressions |
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+--------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------+
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| ``where ma.getMethod().hasName("equals") and ma.getArgument(0).(StringLiteral).getValue() = ""`` | Defines a condition on the variables. | ``ma.getMethod().hasName("equals")`` restricts ``ma`` to only calls to methods call ``equals``. |
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| ``where mc.getMethod().hasName("equals") and mc.getArgument(0).(StringLiteral).getValue() = ""`` | Defines a condition on the variables. | ``mc.getMethod().hasName("equals")`` restricts ``mc`` to only calls to methods call ``equals``. |
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| | | |
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| | | ``ma.getArgument(0).(StringLiteral).getValue() = ""`` says the argument must be literal ``""``. |
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| | | ``mc.getArgument(0).(StringLiteral).getValue() = ""`` says the argument must be literal ``""``. |
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+--------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------+
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| ``select ma, "This comparison to empty string is inefficient, use isEmpty() instead."`` | Defines what to report for each match. | Reports the resulting ``.equals`` expression with a string that explains the problem. |
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| ``select mc, "This comparison to empty string is inefficient, use isEmpty() instead."`` | Defines what to report for each match. | Reports the resulting ``.equals`` expression with a string that explains the problem. |
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| | | |
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| | ``select`` statements for queries that are used to find instances of poor coding practice are always in the form: | |
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| | ``select <program element>, "<alert message>"`` | |
@@ -110,7 +114,7 @@ In this case, it is not possible to simply use ``o.isEmpty()`` instead, as ``o``
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.. code-block:: ql
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ma.getQualifier().getType() instanceof TypeString
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mc.getQualifier().getType() instanceof TypeString
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The ``where`` clause is now:
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@@ -119,7 +123,9 @@ In this case, it is not possible to simply use ``o.isEmpty()`` instead, as ``o``
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where
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ma.getQualifier().getType() instanceof TypeString and
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ma.getMethod().hasName("equals") and
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ma.getArgument(0).(StringLiteral).getValue() = ""
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mc.getQualifier().getType() instanceof TypeString and
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mc.getMethod().hasName("equals") and
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mc.getArgument(0).(StringLiteral).getValue() = ""
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#. Re-run the query.
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@@ -137,8 +143,6 @@ Further reading
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.. |language-code| replace:: ``java``
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.. |example-url| replace:: https://github.com/apache/activemq
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.. |image-quick-query| image:: ../images/codeql-for-visual-studio-code/quick-query-tab-java.png
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.. |result-col-1| replace:: The first column corresponds to the expression ``ma`` and is linked to the location in the source code of the project where ``ma`` occurs.
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.. |result-col-1| replace:: The first column corresponds to the expression ``mc`` and is linked to the location in the source code of the project where ``mc`` occurs.

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