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:
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 | 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:
1 2 3 4 5 | // 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. |
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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”));