JDK new features - 版本历史

2024年10月29日 (二) 01:53 Riguz

2024-10-29T01:53:08Z

←上一版本		2024年10月29日 (二) 01:53的版本
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			__TOC__
	=New Language Features=		=New Language Features=
	== Pattern Matching for switch ==		== Pattern Matching for switch ==

Riguz：/* Improved Warnings */

2024-10-28T09:19:52Z

Improved Warnings

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	</syntaxhighlight>		</syntaxhighlight>

	~~<references>~~		<ref>[https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features-since-jdk-8-to-21/ A categorized list of all Java and JVM features since JDK 8 to 21]</ref>
	<ref ~~name="jvm-features"~~>[https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features-since-jdk-8-to-21/ A categorized list of all Java and JVM features since JDK 8 to 21]</ref>		<ref>[https://advancedweb.hu/new-language-features-since-java-8-to-21/ New language features since Java 8 to 21 - Advanced Web Machinery]</ref>
	<ref ~~name="jvm-lang-features"~~>[https://advancedweb.hu/new-language-features-since-java-8-to-21/ New language features since Java 8 to 21 - Advanced Web Machinery]</ref>
	~~</references>~~

	[[Category:JDK]]		[[Category:JDK]]
	[[Category:Java]]		[[Category:Java]]

Riguz：/* Improved Warnings */

2024-10-28T09:19:31Z

Improved Warnings

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	<references>		<references>
	<ref>[https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features-since-jdk-8-to-21/ A categorized list of all Java and JVM features since JDK 8 to 21]</ref>		<ref name="jvm-features">[https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features-since-jdk-8-to-21/ A categorized list of all Java and JVM features since JDK 8 to 21]</ref>
	<ref>[https://advancedweb.hu/new-language-features-since-java-8-to-21/ New language features since Java 8 to 21 - Advanced Web Machinery]</ref>		<ref name="jvm-lang-features">[https://advancedweb.hu/new-language-features-since-java-8-to-21/ New language features since Java 8 to 21 - Advanced Web Machinery]</ref>
	</references>		</references>

	[[Category:JDK]]		[[Category:JDK]]
	[[Category:Java]]		[[Category:Java]]

Riguz：/* Improved Warnings */

2024-10-28T09:17:40Z

Improved Warnings

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	</syntaxhighlight>		</syntaxhighlight>

			<references>
	<ref>[https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features-since-jdk-8-to-21/ A categorized list of all Java and JVM features since JDK 8 to 21]</ref>		<ref>[https://advancedweb.hu/a-categorized-list-of-all-java-and-jvm-features-since-jdk-8-to-21/ A categorized list of all Java and JVM features since JDK 8 to 21]</ref>
	<ref>[https://advancedweb.hu/new-language-features-since-java-8-to-21/ New language features since Java 8 to 21 - Advanced Web Machinery]</ref>		<ref>[https://advancedweb.hu/new-language-features-since-java-8-to-21/ New language features since Java 8 to 21 - Advanced Web Machinery]</ref>
			</references>

	[[Category:JDK]]		[[Category:JDK]]
	[[Category:Java]]		[[Category:Java]]

Riguz：/* Improved Warnings */

2024-10-28T09:16:31Z

Improved Warnings

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	==Improved Warnings ==		==Improved Warnings ==
	Since {{Label \|red\| JDK 9}}		Since {{Label \|red\| JDK 9}}

			Now it's possible to annotate a private method with @SafeVarargs to mark a Type safety: Potential heap pollution via varargs parameter warning false positive.

			<syntaxhighlight lang="java">
			// Otherwise you get warning:
			// Note: Geeksforgeeks.java uses unchecked or unsafe operations.
			// Note: Recompile with -Xlint:unchecked for details.
			@SafeVarargs
			private void print(List... topics)
			{
			for (List<String> topic : topics) {
			System.out.println(topic);
			}
			}

			</syntaxhighlight>

Riguz：/* Underscore is no longer a valid identifier name */

2024-10-28T09:11:56Z

Underscore is no longer a valid identifier name

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	==Underscore is no longer a valid identifier name ==		==Underscore is no longer a valid identifier name ==
	Since {{Label \|red\| JDK 9}}		Since {{Label \|red\| JDK 9}}

			In Java 8, the compiler emits a warning when '_' is used as an identifier. Java 9 took this a step further making the sole underscore character illegal as an identifier, reserving this name to have special semantics in the future.
			Note: this changes with Unnamed variables, a preview feature in Java 21, where underscores are allowed and convey special meaning.

			<syntaxhighlight lang="java">
			// Compile error in Java 9+
			// unless you run Java 21 with preview features enabled
			int _ = 10;
			</syntaxhighlight>

	==Improved Warnings ==		==Improved Warnings ==

Riguz：/* Allow effectively-final variables to be used as resources in try-with-resources statements */

2024-10-28T09:09:49Z

Allow effectively-final variables to be used as resources in try-with-resources statements

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 ==Allow effectively-final variables to be used as resources in try-with-resources statements ==
 Since {{Label |red| JDK 9}}
 ==Underscore is no longer a valid identifier name ==

Riguz：/* Diamond operator for anonymous inner classes */

2024-10-28T09:06:15Z

Diamond operator for anonymous inner classes

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 ==Diamond operator for anonymous inner classes ==
 Since {{Label |red| JDK 9}}
 ==Allow effectively-final variables to be used as resources in try-with-resources statements ==

Riguz：/* Allow private methods in interfaces */

2024-10-28T08:57:52Z

Allow private methods in interfaces

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	==Allow private methods in interfaces ==		==Allow private methods in interfaces ==
	Since {{Label \|red\| JDK 9}}		Since {{Label \|red\| JDK 9}}

			Since Java 8 it is possible to add default methods to interfaces. With Java 9 these default methods can even call private methods to share code in case you are in a need for reuse, but do not want to expose functionality publicly.

	==Diamond operator for anonymous inner classes ==		==Diamond operator for anonymous inner classes ==

Riguz：/* Local-Variable Type Inference */

2024-10-28T08:56:50Z

Local-Variable Type Inference

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	The type of the declared variables is inferred at compile time.		The type of the declared variables is inferred at compile time.

			Also, it has been introduced cautiously, var is not a new keyword but a reserved type name. This means that it only has special meaning when it's used as a type name, everywhere else var is continuing to be a valid identifier.

			Currently, var does not have an immutable counterpart (such as val or const) to declare a final variable and infer its type with a single keyword. Hopefully, we'll get it in a future release, until then, we can resort to final var.

	==Allow private methods in interfaces ==		==Allow private methods in interfaces ==

JDK new features - 版本历史

2024年10月29日 (二) 01:53 Riguz

Riguz：​/* Improved Warnings */

Riguz：​/* Improved Warnings */

Riguz：​/* Improved Warnings */

Riguz：​/* Improved Warnings */

Riguz：​/* Underscore is no longer a valid identifier name */

Riguz：​/* Allow effectively-final variables to be used as resources in try-with-resources statements */

Riguz：​/* Diamond operator for anonymous inner classes */

Riguz：​/* Allow private methods in interfaces */

Riguz：​/* Local-Variable Type Inference */

Riguz：/* Improved Warnings */

Riguz：/* Improved Warnings */

Riguz：/* Improved Warnings */

Riguz：/* Improved Warnings */

Riguz：/* Underscore is no longer a valid identifier name */

Riguz：/* Allow effectively-final variables to be used as resources in try-with-resources statements */

Riguz：/* Diamond operator for anonymous inner classes */

Riguz：/* Allow private methods in interfaces */

Riguz：/* Local-Variable Type Inference */