Learning #Java is a never-ending story for me: I just learned about " double-brace initialization", which creates an anonymous class derived from the specified class (the outer braces), and provides an initialiser block within that class (the inner braces). e.g. 👇
For example, this code:
List<Integer> l = new ArrayList<>();
l.add(1);
l.add(2);
May look like:
new ArrayList<Integer>() {{
add(1);
add(2);
}};
List<Integer> l = new ArrayList<>();
l.add(1);
l.add(2);
May look like:
new ArrayList<Integer>() {{
add(1);
add(2);
}};
Or it may look like constructor with named parameters:
public class User {
String name;
String surname;
String email;
}
User user = new User() {{
name = "John";
surname = "Doe";
}};
public class User {
String name;
String surname;
String email;
}
User user = new User() {{
name = "John";
surname = "Doe";
}};
Note that an effect of using this double brace initialisation is that you're creating anonymous inner classes. The created class has an implicit `this` pointer to the surrounding outer class.
Whilst not usually a problem, it can cause grief in some circumstances, e.g. when serialising or garbage collecting, and it's worth being aware of this.
While this is interesting to know, it's not recommended to use it:
jesperdj.com/2016/07/19/don…
While this is interesting to know, it's not recommended to use it:
jesperdj.com/2016/07/19/don…
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1. Follow me @xpvit for more Java, Cloud, and Linux knowledge.
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