问题
I am learning filtering using java stream. But the stream after filtering is not printing anything. I think the filter method is not getting executed. My filtering code is as follows:
Stream.of("d2", "a2", "b1", "b3", "c")
.filter(s -> {
s.startsWith("b");
System.out.println("filter: " + s);
return true;
});
There is no compilation error and no exception also. Any suggestion?
回答1:
filter is an intermediate operation, which will be executed only if the Stream pipeline ends in a terminal operation.
For example :
Stream.of("d2", "a2", "b1", "b3", "c")
.filter(s -> {
s.startsWith("b");
System.out.println("filter: " + s);
return true;
})
.forEach (System.out::println);
As it is, your filter method is useless, since it always returns true, and thus performs no filtering.
来源：https://stackoverflow.com/questions/40862906/java-8-stream-why-is-filter-method-not-executing