public void setComparisonOperator(String comparisonOperator) {
        this.comparisonOperator = comparisonOperator;
    }
<p>
A comparator for evaluating attributes in the <code>AttributeValueList</code>. For example, equals, greater than,
less than, etc.
</p>
<p>
The following comparison operators are available:
</p>
<p>
<code>EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN</code>
</p>
<p>
The following are descriptions of each comparison operator.
</p>
<ul>
<li>
<p>
<code>EQ</code> : Equal. <code>EQ</code> is supported for all data types, including lists and maps.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String, Number,
Binary, String Set, Number Set, or Binary Set. If an item contains an <code>AttributeValue</code> element of a
different type than the one provided in the request, the value does not match. For example,
<code>{"S":"6"}</code> does not equal <code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not equal
<code>{"NS":["6", "2", "1"]}</code>.
</p>
<p/></li>
<li>
<p>
<code>NE</code> : Not equal. <code>NE</code> is supported for all data types, including lists and maps.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> of type String, Number, Binary,
String Set, Number Set, or Binary Set. If an item contains an <code>AttributeValue</code> of a different type
than the one provided in the request, the value does not match. For example, <code>{"S":"6"}</code> does not
equal <code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not equal <code>{"NS":["6", "2", "1"]}</code>.
</p>
<p/></li>
<li>
<p>
<code>LE</code> : Less than or equal.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String, Number,
or Binary (not a set type). If an item contains an <code>AttributeValue</code> element of a different type than
the one provided in the request, the value does not match. For example, <code>{"S":"6"}</code> does not equal
<code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not compare to <code>{"NS":["6", "2", "1"]}</code>.
</p>
<p/></li>
<li>
<p>
<code>LT</code> : Less than.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> of type String, Number, or
Binary (not a set type). If an item contains an <code>AttributeValue</code> element of a different type than the
one provided in the request, the value does not match. For example, <code>{"S":"6"}</code> does not equal
<code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not compare to <code>{"NS":["6", "2", "1"]}</code>.
</p>
<p/></li>
<li>
<p>
<code>GE</code> : Greater than or equal.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String, Number,
or Binary (not a set type). If an item contains an <code>AttributeValue</code> element of a different type than
the one provided in the request, the value does not match. For example, <code>{"S":"6"}</code> does not equal
<code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not compare to <code>{"NS":["6", "2", "1"]}</code>.
</p>
<p/></li>
<li>
<p>
<code>GT</code> : Greater than.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String, Number,
or Binary (not a set type). If an item contains an <code>AttributeValue</code> element of a different type than
the one provided in the request, the value does not match. For example, <code>{"S":"6"}</code> does not equal
<code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not compare to <code>{"NS":["6", "2", "1"]}</code>.
</p>
<p/></li>
<li>
<p>
<code>NOT_NULL</code> : The attribute exists. <code>NOT_NULL</code> is supported for all data types, including
lists and maps.
</p>
<note>
<p>
This operator tests for the existence of an attribute, not its data type. If the data type of attribute "
<code>a</code>" is null, and you evaluate it using <code>NOT_NULL</code>, the result is a Boolean
<code>true</code>. This result is because the attribute "<code>a</code>" exists; its data type is not relevant to
the <code>NOT_NULL</code> comparison operator.
</p>
</note></li>
<li>
<p>
<code>NULL</code> : The attribute does not exist. <code>NULL</code> is supported for all data types, including
lists and maps.
</p>
<note>
<p>
This operator tests for the nonexistence of an attribute, not its data type. If the data type of attribute "
<code>a</code>" is null, and you evaluate it using <code>NULL</code>, the result is a Boolean <code>false</code>.
This is because the attribute "<code>a</code>" exists; its data type is not relevant to the <code>NULL</code>
comparison operator.
</p>
</note></li>
<li>
<p>
<code>CONTAINS</code> : Checks for a subsequence, or value in a set.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String, Number,
or Binary (not a set type). If the target attribute of the comparison is of type String, then the operator checks
for a substring match. If the target attribute of the comparison is of type Binary, then the operator looks for a
subsequence of the target that matches the input. If the target attribute of the comparison is a set ("
<code>SS</code>", "<code>NS</code>", or "<code>BS</code>"), then the operator evaluates to true if it finds an
exact match with any member of the set.
</p>
<p>
CONTAINS is supported for lists: When evaluating "<code>a CONTAINS b</code>", "<code>a</code>
" can be a list; however, "<code>b</code>" cannot be a set, a map, or a list.
</p>
</li>
<li>
<p>
<code>NOT_CONTAINS</code> : Checks for absence of a subsequence, or absence of a value in a set.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String, Number,
or Binary (not a set type). If the target attribute of the comparison is a String, then the operator checks for
the absence of a substring match. If the target attribute of the comparison is Binary, then the operator checks
for the absence of a subsequence of the target that matches the input. If the target attribute of the comparison
is a set ("<code>SS</code>", "<code>NS</code>", or "<code>BS</code>"), then the operator evaluates to true if it
<i>does not</i> find an exact match with any member of the set.
</p>
<p>
NOT_CONTAINS is supported for lists: When evaluating "<code>a NOT CONTAINS b</code>", "<code>a</code>
" can be a list; however, "<code>b</code>" cannot be a set, a map, or a list.
</p>
</li>
<li>
<p>
<code>BEGINS_WITH</code> : Checks for a prefix.
</p>
<p>
<code>AttributeValueList</code> can contain only one <code>AttributeValue</code> of type String or Binary (not a
Number or a set type). The target attribute of the comparison must be of type String or Binary (not a Number or a
set type).
</p>
<p/></li>
<li>
<p>
<code>IN</code> : Checks for matching elements in a list.
</p>
<p>
<code>AttributeValueList</code> can contain one or more <code>AttributeValue</code> elements of type String,
Number, or Binary. These attributes are compared against an existing attribute of an item. If any elements of the
input are equal to the item attribute, the expression evaluates to true.
</p>
</li>
<li>
<p>
<code>BETWEEN</code> : Greater than or equal to the first value, and less than or equal to the second value.
</p>
<p>
<code>AttributeValueList</code> must contain two <code>AttributeValue</code> elements of the same type, either
String, Number, or Binary (not a set type). A target attribute matches if the target value is greater than, or
equal to, the first element and less than, or equal to, the second element. If an item contains an
<code>AttributeValue</code> element of a different type than the one provided in the request, the value does not
match. For example, <code>{"S":"6"}</code> does not compare to <code>{"N":"6"}</code>. Also,
<code>{"N":"6"}</code> does not compare to <code>{"NS":["6", "2", "1"]}</code>
</p>
</li>
</ul>

@param comparisonOperator
       A comparator for evaluating attributes in the <code>AttributeValueList</code>. For example, equals,
       greater than, less than, etc.</p>
       <p>
       The following comparison operators are available:
       </p>
       <p>
       <code>EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN</code>
       </p>
       <p>
       The following are descriptions of each comparison operator.
       </p>
       <ul>
       <li>
       <p>
       <code>EQ</code> : Equal. <code>EQ</code> is supported for all data types, including lists and maps.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String,
       Number, Binary, String Set, Number Set, or Binary Set. If an item contains an <code>AttributeValue</code>
       element of a different type than the one provided in the request, the value does not match. For example,
       <code>{"S":"6"}</code> does not equal <code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not equal
       <code>{"NS":["6", "2", "1"]}</code>.
       </p>
       <p/></li>
       <li>
       <p>
       <code>NE</code> : Not equal. <code>NE</code> is supported for all data types, including lists and maps.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> of type String, Number,
       Binary, String Set, Number Set, or Binary Set. If an item contains an <code>AttributeValue</code> of a
       different type than the one provided in the request, the value does not match. For example,
       <code>{"S":"6"}</code> does not equal <code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not equal
       <code>{"NS":["6", "2", "1"]}</code>.
       </p>
       <p/></li>
       <li>
       <p>
       <code>LE</code> : Less than or equal.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String,
       Number, or Binary (not a set type). If an item contains an <code>AttributeValue</code> element of a
       different type than the one provided in the request, the value does not match. For example,
       <code>{"S":"6"}</code> does not equal <code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not
       compare to <code>{"NS":["6", "2", "1"]}</code>.
       </p>
       <p/></li>
       <li>
       <p>
       <code>LT</code> : Less than.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> of type String, Number,
       or Binary (not a set type). If an item contains an <code>AttributeValue</code> element of a different type
       than the one provided in the request, the value does not match. For example, <code>{"S":"6"}</code> does
       not equal <code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not compare to
       <code>{"NS":["6", "2", "1"]}</code>.
       </p>
       <p/></li>
       <li>
       <p>
       <code>GE</code> : Greater than or equal.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String,
       Number, or Binary (not a set type). If an item contains an <code>AttributeValue</code> element of a
       different type than the one provided in the request, the value does not match. For example,
       <code>{"S":"6"}</code> does not equal <code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not
       compare to <code>{"NS":["6", "2", "1"]}</code>.
       </p>
       <p/></li>
       <li>
       <p>
       <code>GT</code> : Greater than.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String,
       Number, or Binary (not a set type). If an item contains an <code>AttributeValue</code> element of a
       different type than the one provided in the request, the value does not match. For example,
       <code>{"S":"6"}</code> does not equal <code>{"N":"6"}</code>. Also, <code>{"N":"6"}</code> does not
       compare to <code>{"NS":["6", "2", "1"]}</code>.
       </p>
       <p/></li>
       <li>
       <p>
       <code>NOT_NULL</code> : The attribute exists. <code>NOT_NULL</code> is supported for all data types,
       including lists and maps.
       </p>
       <note>
       <p>
       This operator tests for the existence of an attribute, not its data type. If the data type of attribute "
       <code>a</code>" is null, and you evaluate it using <code>NOT_NULL</code>, the result is a Boolean
       <code>true</code>. This result is because the attribute "<code>a</code>" exists; its data type is not
       relevant to the <code>NOT_NULL</code> comparison operator.
       </p>
       </note></li>
       <li>
       <p>
       <code>NULL</code> : The attribute does not exist. <code>NULL</code> is supported for all data types,
       including lists and maps.
       </p>
       <note>
       <p>
       This operator tests for the nonexistence of an attribute, not its data type. If the data type of attribute
       "<code>a</code>" is null, and you evaluate it using <code>NULL</code>, the result is a Boolean
       <code>false</code>. This is because the attribute "<code>a</code>" exists; its data type is not relevant
       to the <code>NULL</code> comparison operator.
       </p>
       </note></li>
       <li>
       <p>
       <code>CONTAINS</code> : Checks for a subsequence, or value in a set.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String,
       Number, or Binary (not a set type). If the target attribute of the comparison is of type String, then the
       operator checks for a substring match. If the target attribute of the comparison is of type Binary, then
       the operator looks for a subsequence of the target that matches the input. If the target attribute of the
       comparison is a set ("<code>SS</code>", "<code>NS</code>", or "<code>BS</code>"), then the operator
       evaluates to true if it finds an exact match with any member of the set.
       </p>
       <p>
       CONTAINS is supported for lists: When evaluating "<code>a CONTAINS b</code>", "<code>a</code>
       " can be a list; however, "<code>b</code>" cannot be a set, a map, or a list.
       </p>
       </li>
       <li>
       <p>
       <code>NOT_CONTAINS</code> : Checks for absence of a subsequence, or absence of a value in a set.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> element of type String,
       Number, or Binary (not a set type). If the target attribute of the comparison is a String, then the
       operator checks for the absence of a substring match. If the target attribute of the comparison is Binary,
       then the operator checks for the absence of a subsequence of the target that matches the input. If the
       target attribute of the comparison is a set ("<code>SS</code>", "<code>NS</code>", or "<code>BS</code>"),
       then the operator evaluates to true if it <i>does not</i> find an exact match with any member of the set.
       </p>
       <p>
       NOT_CONTAINS is supported for lists: When evaluating "<code>a NOT CONTAINS b</code>", "<code>a</code>
       " can be a list; however, "<code>b</code>" cannot be a set, a map, or a list.
       </p>
       </li>
       <li>
       <p>
       <code>BEGINS_WITH</code> : Checks for a prefix.
       </p>
       <p>
       <code>AttributeValueList</code> can contain only one <code>AttributeValue</code> of type String or Binary
       (not a Number or a set type). The target attribute of the comparison must be of type String or Binary (not
       a Number or a set type).
       </p>
       <p/></li>
       <li>
       <p>
       <code>IN</code> : Checks for matching elements in a list.
       </p>
       <p>
       <code>AttributeValueList</code> can contain one or more <code>AttributeValue</code> elements of type
       String, Number, or Binary. These attributes are compared against an existing attribute of an item. If any
       elements of the input are equal to the item attribute, the expression evaluates to true.
       </p>
       </li>
       <li>
       <p>
       <code>BETWEEN</code> : Greater than or equal to the first value, and less than or equal to the second
       value.
       </p>
       <p>
       <code>AttributeValueList</code> must contain two <code>AttributeValue</code> elements of the same type,
       either String, Number, or Binary (not a set type). A target attribute matches if the target value is
       greater than, or equal to, the first element and less than, or equal to, the second element. If an item
       contains an <code>AttributeValue</code> element of a different type than the one provided in the request,
       the value does not match. For example, <code>{"S":"6"}</code> does not compare to <code>{"N":"6"}</code>.
       Also, <code>{"N":"6"}</code> does not compare to <code>{"NS":["6", "2", "1"]}</code>
       </p>
       </li>
@see ComparisonOperator
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/model/ExpectedAttributeValue.java