获取列表中包含“.txt”的索引而不使用 JAVA 中的循环

Question

I would like to get the first index of a string that contains a ".txt" in the list using JAVA. without doing any loop. Because I have lots of value in File like:

["sample.txt", "sample.csv","sample.docx","sample","sample.xlsx","sample2.txt, ...];

I only need the index of "sample.txt"

List<String> files = Arrays.asList(fileList).stream()
                             .map(x -> x.getAbsolutePath())
                             .collect(Collectors.toList());
index = files.indexOf(?);

Answer 1

Are you looking to use:

List<String> list = Arrays.asList(fileList);

String first = list.stream(fileList)
        .filter(x -> x.endsWith(".txt")) // or contains if the .txt can be in the middle
        .findFirst()
        .orElse(null); // you can even throw and exception using orElseThrow

// to get the index you can use
int index = list.indexOf(first);