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<h4>Boolean expressions</h4>

<p>Groovy supports the standard conditional operators on boolean expressions, e.g.:</p>
<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
def a = true
def b = true
def c = false
assert a
assert a &amp;&amp; b
assert a || c
assert !c
</pre></td></tr></table>

<p>In addition, Groovy has special rules for coercing non-boolean objects to a boolean value.</p>

<h4>Collections</h4>

<p>Empty collections are coerced to false.</p>

<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
def numbers = [1,2,3]
assert numbers //true, as numbers in not empty
numbers = []
assert !numbers //true, as numbers is now an empty collection
</pre></td></tr></table>

<h4>Iterators and Enumerations</h4>

<p>Iterators and Enumerations with no further elements are coerced to false.</p>

<table class="wysiwyg-macro" data-macro-name="code" style="background-image: url(/plugins/servlet/confluence/placeholder/macro-heading?definition=e2NvZGV9&amp;locale=en_GB&amp;version=2); background-repeat: no-repeat;" data-macro-body-type="PLAIN_TEXT"><tr><td class="wysiwyg-macro-body"><pre>
assert ![].iterator() // false because the Iterator is empty
assert [0].iterator() // true because the Iterator has a next element
def v = new Vector()
assert !v.elements()  // false because the Enumeration is empty
v.add(new Object())
assert v.elements()   // true because the Enumeration has more elements
</pre></td></tr></table>

<p>Non-empty maps are coerced to true.</p>

<h4>Matchers</h4>

<p>Matching regex patterns are coerced to true.</p>

<h4>Strings</h4>

<p>Non-empty Strings, GStrings and CharSequences are coerced to true.</p>

<h4>Numbers</h4>

<p>Non-zero numbers are coerced to true.</p>

<h4>Object references</h4>

<p>Non-null object references are coerced to true.</p>