我的任务是以字符串数组的形式订购BigDecimals。我的想法是使用BigDecimal的String参数构造函数,然后对其进行排序,然后使用forEach将其打印出来。这是部分代码:如何在Java 8中从String数组创建BigDecimal流?
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
String[] s = new String[n + 2];
for (int i = 0; i < n; i++) {
s[i] = sc.next();
}
Stream.of(s)
.map(i -> new BigDecimal(i))
.sorted((bg1, bg2) -> bg1.compareTo(bg2))
.forEach(System.out::println); //line 22
但我得到这个NullPointerException异常对foreach行:
Exception in thread "main" java.lang.NullPointerException
at java.math.BigDecimal.<init>(BigDecimal.java:806)
at Solution.lambda$main$1(Solution.java:20)
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
at java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
at Solution.main(Solution.java:22)
我期待着从流专家听证。
谢谢!
您正在将数组填充到第n个元素,但是您的String []具有大小'n + 2'。所以最后两个元素是默认的'null'。在for循环中更好地将's.length'作为谓词。 – Flown
谢谢!扫描部分也被给出了。我不知道如何调试流,或者... – monami