用Java实现字母排列的三角形

public class HomeWork03 { 
    public static void main(String[] args) {
            String str = "ABCDEFGHIJK";
            for(int i=0; i<str.length(); i++){
                for(int j=i; j<(i+8 > str.length() ? str.length() : i+8); j++){
                    System.out.print(str.substring(i, j+1));
                    System.out.println();
                }
                System.out.println();
            }
    }
}

输出：

A
AB
ABC
ABCD
ABCDE
ABCDEF
ABCDEFG
ABCDEFGH

B
BC
BCD
BCDE
BCDEF
BCDEFG
BCDEFGH
BCDEFGHI

C
CD
CDE
CDEF
CDEFG
CDEFGH
CDEFGHI
CDEFGHIJ

D
DE
DEF
DEFG
DEFGH
DEFGHI
DEFGHIJ
DEFGHIJK

E
EF
EFG
EFGH
EFGHI
EFGHIJ
EFGHIJK

F
FG
FGH
FGHI
FGHIJ
FGHIJK

G
GH
GHI
GHIJ
GHIJK

H
HI
HIJ
HIJK

I
IJ
IJK

J
JK

K