java组合

    public void pailie() {
        String str = "1234567";
        char[] arr1 = str.toCharArray();
        char[] arr2 = Arrays.copyOf(arr1, arr1.length);
        for (int i = 0; i < arr1.length - 1; i++) {
            for (int j = i + 1; j < arr2.length; j++) {
                System.out.print("("+arr1[i] + "," + arr2[j]+")"+"\t");
            }
        }
    }

结果

(1,2) (1,3) (1,4) (1,5) (1,6) (1,7) (2,3) (2,4) (2,5) (2,6) (2,7) (3,4) (3,5) (3,6) (3,7) (4,5) (4,6) (4,7) (5,6) (5,7) (6,7)