Java doesn’t have an easy construct of repeat something N number of times. We can make a for loop of course, but many times we don’t even care about the variable that we created in the loop. We just want repeat N times of some code and that’s it. With the lambda available in Java 8, you may attempt something like this:
public class RepeatDemo {
public static void main(String[] args) {
// One liner repeat
repeat(10, () -> System.out.println("HELLO"));
// Multi-liners repeat
repeat(10, () -> {
System.out.println("HELLO");
System.out.println("WORLD");
});
}
static void repeat(int n, Runnable r) {
for (int i = 0; i < n; i++)
r.run();
}
}
Probably not as eye pleasing or straight forward as the good fashion for-loop, but you do get rid of the unnecessary loop variable. Only if Java 8 would go extra mile and treat the lambda argument in method with sugar syntax, then we could have it something like the Scala/Groovy style, which makes code more smoother. For example:
// Wouldn't this be nice to have in Java?
repeat(10) {
System.out.println("HELLO");
System.out.println("WORLD");
}
Hum….
| Reference: | Creating your own loop structure in Java 8 lambda from our JCG partner Zemian Deng at the A Programmer’s Journal blog. |
interesting post, thanks…
I created a simple class with Builder pattern that creates a loop with this usage style :
link
public static void main(String[] args) {
loop().from(2).to(10).doIt(() -> System.out.println(“Hello World!”));
}
Hi, unless you do want to get rid of redundant loop variable why not to do it this way:
import static java.util.stream.IntStream.*;
range(1, 5).forEach((i)-> System.out.println(“HELLO”));