在Java中将字符串拆分为多个子字符串
给定一个字符串，它的任务是将字符串拆分为多个子字符串。
Java中的字符串可以是 0 个或多个字符。
例子 ：
(a) "" is a String in java with 0 character
(b) "d" is a String in java with 1 character
(c) "This is a sentence." is a string with 19 characters.
子字符串：作为另一个字符串一部分的字符串称为另一个字符串的子字符串。
示例 1：让我们考虑字符串bat 。可能的子串是：
(1) "b"
(2) "ba"
(3) "bat", every string is a substring of itself
(4) "a"
(5) "at"
(6) "t"
(7) "" , "" is a substring of every string
示例 2：让我们考虑字符串The Cat 。可能的子串是：
(1) "T"
(2) "Th"
(3) "The"
(4) "The "
(5) "The C"
(6) "The Ca"
(7) "The Cat", every string is a substring of itself
(8) "h"
(9) "he"
(10) "he "
(11) "he C"
(12) "he Ca"
(13) "he Cat"
(14) "e"
(15) "e "
(16) "e C"
(17) "e Ca"
(18) "e Cat"
(19) " "
(20) " C"
(21) " Ca"
(22) " Cat"
(23) "C"
(24) "Ca"
(25) "Cat"
(26) "a"
(27) "at"
(28) "t"
(29) "" , "" is a substring of every string
注：总计 长度为N的字符串的子字符串数是(N * (N + 1)) / 2 。这是在排除空字符串“”之后，因为它是所有字符串的子字符串。
方法：
Let us consider a string which has n characters:
1. For each character at index i (0 to n-1):
find substrings of length 1, 2, ..., n-i
Example: Let our string be cat, here n = 3 (the length of string)
here,
index of 'c' is 0
index of 'a' is 1
index of 't' is 2
Loop from i = 0 to 2: (since n-1 = 2)
When i = 0:
Substring of length 1 : "c"
Substring of length 2 : "ca"
Substring of length 3 : "cat" , (substring of length n-i or 3-0 = 3)
When i = 1:
Substring of length 1 : "a"
Substring of length 2 : "at" , (substring of length n-i or 3-1 = 2)
When i = 2:
Substring of length 1 : "t" , (substring of length n-i or 3-2 = 1)
例子：
Java
// Java Program to split a string into all possible
// substrings excluding the string with 0 characters i.e. ""
import java.io.*;
import java.util.ArrayList;
class SubstringsOfAString {
// function to split a string into all its substrings
// and return the list as an object of ArrrayList
public static ArrayList
splitSubstrings(String s)
{
// variables to traverse through the
// string
int i, j;
// to store the length of the
// string
int stringLength = s.length();
// List object to store the list of
// all substrings of the string s
ArrayList subStringList
= new ArrayList();
// first for loop
for (i = 0; i < stringLength; i++) {
for (j = i + 1; j <= stringLength; j++) {
subStringList.add(s.substring(i, j));
}
} // end of first for loop
// returning the list (object
// of ArrayList) of substrings
// of string s
return subStringList;
}
public static void main(String[] args)
{
// here "The Cat" is our input string
String stringInput = new String("The Cat");
ArrayList subStringList
= SubstringsOfAString.splitSubstrings(
stringInput);
System.out.println(
"\nSubstring list printed as an ArrayList : ");
System.out.println(subStringList);
System.out.println(
"\n\nAll substrings printed 1 per line : ");
int count = 1;
// each substring would be printed
// within double quotes
for (String it : subStringList) {
System.out.println("(" + count + ") \"" + it
+ "\"");
count++;
}
}
} 输出
Substring list printed as an ArrayList :
[T, Th, The, The , The C, The Ca, The Cat, h, he, he , he C, he Ca, he Cat, e, e , e C, e Ca, e Cat, , C, Ca, Cat, C, Ca, Cat, a, at, t]
All substrings printed 1 per line :
(1) "T"
(2) "Th"
(3) "The"
(4) "The "
(5) "The C"
(6) "The Ca"
(7) "The Cat"
(8) "h"
(9) "he"
(10) "he "
(11) "he C"
(12) "he Ca"
(13) "he Cat"
(14) "e"
(15) "e "
(16) "e C"
(17) "e Ca"
(18) "e Cat"
(19) " "
(20) " C"
(21) " Ca"
(22) " Cat"
(23) "C"
(24) "Ca"
(25) "Cat"
(26) "a"
(27) "at"
(28) "t"
时间复杂度：O(n 2 ) 其中n是字符串的长度
输出 1：当字符串输入 = bat
Substring list printed as an ArrayList :
[b, ba, bat, a, at, t]
All substrings printed 1 per line :
(1) "b"
(2) "ba"
(3) "bat"
(4) "a"
(5) "at"
(6) "t"
输出 2：当字符串输入 = The Cat
Substring list printed as an ArrayList :
[T, Th, The, The , The C, The Ca, The Cat, h, he, he , he C, he Ca, he Cat, e, e , e C, e Ca, e Cat, , C, Ca, Cat, C, Ca, Cat, a, at, t]
All substrings printed 1 per line :
(1) "T"
(2) "Th"
(3) "The"
(4) "The "
(5) "The C"
(6) "The Ca"
(7) "The Cat"
(8) "h"
(9) "he"
(10) "he "
(11) "he C"
(12) "he Ca"
(13) "he Cat"
(14) "e"
(15) "e "
(16) "e C"
(17) "e Ca"
(18) "e Cat"
(19) " "
(20) " C"
(21) " Ca"
(22) " Cat"
(23) "C"
(24) "Ca"
(25) "Cat"
(26) "a"
(27) "at"
(28) "t"