What to use instead of Class.newInstance()?

Question

Class.newInstance() is marked deprecated. Documentation does not suggest any alternatives. How are we meant to create instances now?

Which documentation?
– Sotirios Delimanolis
Commented Sep 24, 2017 at 19:13 — Sotirios Delimanolis, Commented Sep 24, 2017 at 19:13

Mureinik · Accepted Answer · 2017-09-24 19:16:42Z

268

The call

clazz.newInstance()

can be replaced by

clazz.getDeclaredConstructor().newInstance()

answered Sep 24, 2017 at 19:16

Mureinik

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6

What about java 8?. I can't find getDeclaredConstructor() method without parameters there.
– Yurii Kozachok
Commented Sep 30, 2019 at 6:33
2

@YuriiKozachok You could use getConstrouctor, although note it will only return public constructors. Also, note that newInstance isn't deprecated in Java 8 (although using it still has all the problems that made the JDK developers deprecate it in 9...)
– Mureinik
Commented Sep 30, 2019 at 6:40
@Shtefan Where are you seeing that? The java 17 docs don't mark it as deprecated AFAICT: docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/…
– elhefe
Commented Oct 22, 2021 at 22:08
@elhefe newInstance isn't deprecated. Using newInstance on a class IS deprecated.
– IndevSmiles
Commented Dec 9, 2021 at 21:49
3

@YuriiKozachok getDeclaredConstructor(Class<?>... paramTypes) is variadic - so you can invoke it with 0 arguments.
– Johannes Kuhn
Commented Mar 13, 2022 at 16:29

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Andy Turner · Accepted Answer · 2017-09-24 19:13:53Z

26

Class.getDeclaredConstructor(...).newInstance(...)

Refer to Google errorprone's documentation (for example) for a description of why.

answered Sep 24, 2017 at 19:13

Andy Turner

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