没有参数和返回值的 Java 8 函数式接口
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Java 8 functional interface with no arguments and no return value
提问by Miguel Gamboa
What is the Java 8 functional interface for a method that takes nothing and returns nothing?
什么是 Java 8 函数式接口，它不接受任何内容也不返回任何内容？
I.e., the equivalent to to the C# parameterless Actionwith voidreturn type?
即，相当于 C# 无参数Action带void返回类型？
采纳答案by assylias
回答by Charana
Just make your own
只做你自己的
@FunctionalInterface
public interface Procedure {
void run();
default Procedure andThen(Procedure after){
return () -> {
this.run();
after.run();
};
}
default Procedure compose(Procedure before){
return () -> {
before.run();
this.run();
};
}
}
and use it like this
并像这样使用它
public static void main(String[] args){
Procedure procedure1 = () -> System.out.print("Hello");
Procedure procedure2 = () -> System.out.print("World");
procedure1.andThen(procedure2).run();
System.out.println();
procedure1.compose(procedure2).run();
}
and the output
和输出
HelloWorld
WorldHello
回答by uma mahesh
@FunctionalInterface allows only method abstract method Hence you can instantiate that interface with lambda expression as below and you can access the interface members
@FunctionalInterface 只允许方法抽象方法因此您可以使用 lambda 表达式实例化该接口，如下所示，您可以访问接口成员
@FunctionalInterface
interface Hai {
void m2();
static void m1() {
System.out.println("i m1 method:::");
}
default void log(String str) {
System.out.println("i am log method:::" + str);
}
}
public class Hello {
public static void main(String[] args) {
Hai hai = () -> {};
hai.log("lets do it.");
Hai.m1();
}
}
output:
i am log method:::lets do it.
i m1 method:::
