如何從字符串數組中獲取 Stream？

Question

我有以下語句創建一個字符串數組：

String[][] strArr = {{"Jazz","80"},{"sam","90"},{"shaam","80"},{"aditya","100"}};

是否有可能得到 stream 如下？ 我在 Eclipse 中嘗試過，但出現錯誤。

Stream<String,String> streamObj = Arrays.stream(strArr);

嘗試在網上搜索，但大多數結果顯示從一維字符串數組中獲取 stream，如下所示：

String[] stringArr = {"a","b","c","d"};
Stream<String> str = Arrays.stream(stringArr);

Answer 1

There is no feasible representation such as Stream<String, String> with the java.util.stream.Stream class since the generic implementation for it relies on a single type such as it declared to be:

public interface Stream<T> ...

您可能仍將子數組中的映射作為Map<String, String>中的鍵值對collect為：

Map<String, String> map = Arrays.stream(strArr)
        .collect(Collectors.toMap(s -> s[0], s -> s[1]));

要進一步包裝條目而不將它們收集到Map ，您可以創建Stream的SimpleEntry為：

Stream<AbstractMap.SimpleEntry<String, String>> entryStream = Arrays.stream(strArr)
        .map(sub -> new AbstractMap.SimpleEntry<>(sub[0], sub[1]));

Answer 2

您可以定義一個名為 StringPair 的 POJO 和 map stream。

public class PairStream {

    public static void main(String[] args) {
        String[][] strArr = {{"Jazz","80"},{"sam","90"},{"shaam","80"},{"aditya","100"}};
        Arrays.stream( strArr ).map( arr -> new StringPair(arr) ).forEach( pair -> System.out.println(pair) );
    }

    private static class StringPair {
        private final String first;
        private final String second;

        public StringPair(String[] array) {
            this.first = array[0];
            this.second = array[1];
        }
        @Override
        public String toString() {
            return "StringPair [first=" + first + ", second=" + second + "]";
        }
    }
}

以及您可以使用Apache Commons lang Pair

public class PairStream {

    public static void main(String[] args) {
        String[][] strArr = {{"Jazz","80"},{"sam","90"},{"shaam","80"},{"aditya","100"}};
        Arrays.stream( strArr ).map( arr -> Pair.of(arr[0],arr[1]) ).forEach( pair -> System.out.println(pair) );
    }


}