One approach might be to allow case labels to be refined such a The problem here is that using a single pattern to discriminate among cases does Then we have to use fall-through to get the correct behavior when the Write a case label that matches all triangles, and then place the test of theĪrea of the triangle rather uncomfortably within the corresponding statement However, we cannot express this directly with a single pattern. Over 100), and a default case for everything else (including small triangles).
#JAVA SWITCH STATEMENT CODE#
The intent of this code is to have a special case for large triangles (with area If.else tests such as: static String formatter(Object o) The existing switch does not support that, we end up with a chain of We might like to use patterns to test the same variableĪgainst a number of possibilities, taking a specific action on each, but since Types, enum types, and String - and you can only test for exact equalityĪgainst constants. You can only switch on values of a few types - numeric Since Java 14, switch expressions ( JEP 361), but unfortunately Java supports multi-way comparisons with switch statements and,
We often want to compare a variable such as o against multipleĪlternatives. This modest extension allows theįamiliar instanceof-and-cast idiom to be simplified: // Old code In Java 16, JEP 394 extended the instanceof operator to take a type Labels are patterns versus when case labels are traditional constants. Pattern-matching semantics that is separate from the traditional switchĭo not make the switch expression or statement behave differently when case Parenthesized patterns, to resolve some parsing ambiguities.Įnsure that all existing switch expressions and statements continue toĬompile with no changes and execute with identical semantics.ĭo not introduce a new switch-like expression or statement with Matching logic to be refined with arbitrary boolean expressions, and Introduce two new kinds of patterns: guarded patterns, to allow pattern Statements by allowing patterns to appear in case labels.Īllow the historical null-hostility of switch to be relaxed when desired. GoalsĮxpand the expressiveness and applicability of switch expressions and This is a preview language feature in JDK 17. Queries can be expressed concisely and safely.
Enhance the Java programming language with pattern matching for switchĮxpressions and statements, along with extensions to the language of patterns.Įxtending pattern matching to switch allows an expression to be tested againstĪ number of patterns, each with a specific action, so that complex data-oriented
0 kommentar(er)
