O'Reilly - Java Message Service

Java Message Service
Numeric literals are expressed using exact numerical (+22, 30, -52134), approximate
numerical with decimal (-33.22, 100.00, +7.0), or scientific (-9E4, 3.5E6) notation.
Boolean literals are expressed as TRUE or FALSE.
D.3 Comparison Operators
Comparison operators compare identifiers to literals in a boolean expression that evaluates
to TRUE or FALSE. Comparison operations can be combined into more complex expressions
using the logical operators AND and OR. Expressions are evaluated from left to right:
Age < 30 AND Weight >= 100.00 OR LName = 'Smith'
In this example, the expression would be evaluated as if it had parentheses placed as
follows:
(Age < 30 AND Weight >= 100.00) OR (LName = 'Smith')
Either the LName must be equal to 'Smith' or the LName can be any value as long as the Age
is less than 30 and the Weight is greater than or equal to 100. Evaluating these kinds of
expressions should be second nature for most programmers.
The following message selector uses three of the six algebraic comparison operators,
which are =, >, >=, = 100.00 OR LName LIKE 'Sm%th'
The LIKE comparison operator attempts to match each character in the literal with
characters of the property value. Two special wildcard characters, underscore (_) and
percent (%), can be used with the LIKE comparison. The underscore stands for any single
character. The percent symbol stands for any sequence of characters. All other characters
stand for themselves and are case sensitive. Table D.1 provides some examples of
successful and unsuccessful comparisons using the LIKE operator.
Table D.1. Comparisons Using the LIKE Operator
Expression True for Values False for Values
LName LIKE 'Sm_th' Smith, Smeth, Sm4th Smooth, Smth, Smiths
LName LIKE 'Smit_' Smith, Smitt, Smit4 Smoth, Smiths
LName LIKE 'Sm%th' Smith, Smoo3th, Smth Smott, Rmith, Smiths
LName LIKE '%ith' Smith, Synoonith, ith Smoth, Smiths
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