无法将Char[]转换为java 8中的stream[重复]

Question

private static char[] getTableFromTwoChits(char[][] inputTwoChits) {
    Map<Character, Character> map = new HashMap<>();
    Arrays.stream(inputTwoChits).forEach(x -> map.put(x[0], x[1]));
    map.entrySet().forEach(System.out::println);
    char[] result = new char[inputTwoChits.length+1]; int index=0;
    char startPoint = inputTwoChits[0][0];
    do {
       result[index] = startPoint;index++;
       startPoint = map.get(startPoint);
    }while(startPoint != inputTwoChits[0][0]);
    result[index] = startPoint;
    return result;
}

主要方法如下-

public static void main(String[] args) {
    char[][] inputTwoChits = {{'A','B'},{'C','D'},{'B','C'},{'E','F'},{'F','A'},{'D','E'}};
    char[] outputTwoChits = getTableFromTwoChits(inputTwoChits);
    Arrays.stream(outputTwoChits).forEach(System.out::println);

}

方法getTableFromTwoChits（）中的第2行正在编译fine，而main方法的第3行没有编译。
请解释这种行为背后的原因是什么？

编译错误如下所述-

/CircularTableTwoChits.java:21: error: no suitable method found for stream(char[])
        Arrays.stream(outputTwoChits).forEach(System.out::println);
              ^
    method Arrays.<T#1>stream(T#1[]) is not applicable
      (inference variable T#1 has incompatible bounds
        equality constraints: char
        upper bounds: Object)
    method Arrays.<T#2>stream(T#2[],int,int) is not applicable
      (cannot infer type-variable(s) T#2
        (actual and formal argument lists differ in length))
    method Arrays.stream(int[]) is not applicable
      (argument mismatch; char[] cannot be converted to int[])
    method Arrays.stream(long[]) is not applicable
      (argument mismatch; char[] cannot be converted to long[])
    method Arrays.stream(double[]) is not applicable
      (argument mismatch; char[] cannot be converted to double[])
  where T#1,T#2 are type-variables:
    T#1 extends Object declared in method <T#1>stream(T#1[])
    T#2 extends Object declared in method <T#2>stream(T#2[],int,int)
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
1 error

Answer 1

对于类型int、long、double和引用类型（对象）的元素，只有四种流类型。因此，由于没有char流，arrays.stream不能应用于char[]数组。

字符流的规范表示是intstream，在没有复制或装箱开销的情况下获取它的工作如下

CharBuffer.wrap(charArray).chars().forEach(c -> System.out.println((char)c));

由于int值的默认解释是“integer number”，因此需要使用将其转换为char的lambda表达式将其解释为“character”。

System.out.println(String.valueOf(charArray));