java8在Stream的forEach操作时获取index
import java.util.Objects; import java.util.function.BiConsumer; /** * * @author yangzhilong * @date 7/15/2019 */ public class ForEachUtils { /** * * @param <T> * @param startIndex 开始遍历的索引 * @param elements 集合 * @param action */ public static <T> void forEach(int startIndex,Iterable<? extends T> elements, BiConsumer<Integer, ? super T> action) { Objects.requireNonNull(elements); Objects.requireNonNull(action); if(startIndex < 0) { startIndex = 0; } int index = 0; for (T element : elements) { index++; if(index <= startIndex) { continue; } action.accept(index-1, element); } } }
使用:
ForEachUtils.forEach(0, list, (index, item) -> {
});
说明:第一个参数为起始索引,第二个是要遍历的集合,第三个参数为BiConsumer类型的处理器。
单元测试:
import java.util.Arrays; import java.util.List; import org.junit.Test; import lombok.extern.slf4j.Slf4j; /** * @author yangzhilong * @date 7/15/2019 */ @Slf4j public class ForEachUtilsTest { @Test public void test() { List<String> list = Arrays.asList("1","2", "3"); ForEachUtils.forEach(0, list, (index, item) -> { log.info(index + " - " + item); }); } @Test public void test1() { List<String> list = Arrays.asList("x","y", "z"); ForEachUtils.forEach(1, list, (index, item) -> { log.info(index + " - " + item); }); } }
输出:
0 - 1 1 - 2 2 - 3
1 - y
2 - z