56 lines
1.9 KiB
Plaintext
56 lines
1.9 KiB
Plaintext
Comparisons of dissimilar types will always return false. The comparison and all its dependent code can simply be removed. This includes:
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* comparing an object with null
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* comparing an object with an unrelated primitive (E.G. a string with an int)
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* comparing unrelated classes
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* comparing an unrelated ``class`` and ``interface``
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* comparing unrelated ``interface`` types
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* comparing an array to a non-array
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* comparing two arrays
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Specifically in the case of arrays, since arrays don't override ``Object.equals()``, calling ``equals`` on two arrays is the same as comparing their addresses. This means that ``array1.equals(array2)`` is equivalent to ``array1==array2``.
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However, some developers might expect ``Array.equals(Object obj)`` to do more than a simple memory address comparison, comparing for instance the size and content of the two arrays. Instead, the ``==`` operator or ``Arrays.equals(array1, array2)`` should always be used with arrays.
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== Noncompliant Code Example
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----
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interface KitchenTool { ... };
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interface Plant {...}
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public class Spatula implements KitchenTool { ... }
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public class Tree implements Plant { ...}
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//...
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Spatula spatula = new Spatula();
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KitchenTool tool = spatula;
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KitchenTool [] tools = {tool};
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Tree tree = new Tree();
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Plant plant = tree;
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Tree [] trees = {tree};
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if (spatula.equals(tree)) { // Noncompliant; unrelated classes
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// ...
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}
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else if (spatula.equals(plant)) { // Noncompliant; unrelated class and interface
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// ...
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}
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else if (tool.equals(plant)) { // Noncompliant; unrelated interfaces
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// ...
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}
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else if (tool.equals(tools)) { // Noncompliant; array & non-array
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// ...
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}
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else if (trees.equals(tools)) { // Noncompliant; incompatible arrays
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// ...
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}
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else if (tree.equals(null)) { // Noncompliant
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// ...
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}
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----
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== See
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* https://wiki.sei.cmu.edu/confluence/x/5zdGBQ[CERT, EXP02-J.] - Do not use the Object.equals() method to compare two arrays
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