实验4 串操作

1、实验报告四 串操作班级： 姓名： 学号： 专业： 一、 实验目的：（1） 掌握串的定义、术语。（2） 掌握串的基本操作算法。（3） 掌握串的匹配算法。二、 实验内容： 1. 在常量串MyString类中，增加以下方法，并求各算法的时间复杂度。public MyString trim()/删除串中所有空格public char toCharArray()/返回字符数组public MyString toLowerCase()/返回将大写字母转换成小写字母的字符串public MyString toUpperCase()/返回将小写字母转换成大写字母的字符串public MyString repl

2、ace(char old, char newc)/用字符newc替换串中的字符oldpublic Boolean equals(Object obj)/判断两个串是否相等public Boolean equalsIgnoreCase(String1 str) /判断两个串是否相等,忽略大小写public int compareTo(MyString str)/比较两个串大小，实现Comparable接口public int compareToIgnoreCase(MyString str) /比较两个串大小，忽略大小写public Boolean startsWith(MyString pre

3、fix)/判断prefix是否前缀子串public Boolean endsWith(MyString suffix)/判断suffix是否前缀子串源代码：package Ex4.Ex4_1;import java.util.Arrays;/* * Created by 74062 on 2017/3/27. */public class MyString implements Comparable public static void main(String args) MyString myString1 = new MyString("a b c d"); MyStr

4、ing myString2 = new MyString("A B C D"); System.out.println(new MyString("a b c d").trim().toString(); System.out.println(mySpareTo(myString2); System.out.println(mySpareToIgnoreCase(myString2); System.out.println(myString1.toUpperCase(); System.out.println(myString1.startsWith(n

5、ew MyString("a "); System.out.println(myString1.endsWith(new MyString(" d"); System.out.println(myString1.replace('a','A'); private final char values; public MyString(char values) this.values = values; public MyString(String string) values = new charstring.length(

6、); for(int i=0;i < string.length();i+) valuesi = string.charAt(i); public MyString trim() char result = new charvalues.length; int count = 0; int j = 0; for(int i=0;i<values.length;i+) if(valuesi != ' ') resultj = valuesi; j+; else count+; result = Arrays.copyOf(result,result.length-co

7、unt); return new MyString(result); public int length() return values.length; public char toCharArray() char temp = new charvalues.length; for(int i=0;i<values.length;i+) tempi = valuesi; return temp; public MyString toLowerCase() char temp = new charvalues.length; for(int i=0 ; i<values.length

8、;i+) if(valuesi>=65&&valuesi<=90) tempi = (char)(valuesi+32); else tempi = valuesi; return new MyString(temp); public MyString toUpperCase() char temp = new charvalues.length; for(int i=0 ; i<values.length;i+) if(valuesi>='a' && valuesi<='z') tempi = (c

9、har)(valuesi-32); else tempi = valuesi; return new MyString(temp); public MyString replace(char old, char newc) char temp = new charvalues.length; for(int i=0;i<values.length;i+) if(valuesi = old ) tempi = newc; else tempi = valuesi; return new MyString(temp); public boolean equals(Object obj) ch

10、ar temp = (MyString)obj).toCharArray(); for(int i=0;i<values.length;i+) if(tempi != valuesi) return false; return true; public Boolean equalsIgnoreCase(MyString str) return this.toLowerCase().equals(str.toLowerCase(); Override public int compareTo(Object o) char chars = (MyString)o).toCharArray()

11、; int length = Math.min(chars.length,values.length); for(int i=0;i<length;i+) if(valuesi-charsi<0) return -1; else if(valuesi-charsi>0) return 1; if(values.length>chars.length) return 1; else if (values.length<chars.length) return -1; else return 0; /* * 比较两个串大小，忽略大小写 * param str * re

12、turn */ public int compareToIgnoreCase(MyString str) return this.toLowerCase().compareTo(str.toLowerCase(); /* * 判断prefix是否前缀子串 * param prefix * return */ public Boolean startsWith(MyString prefix) if(values.length<prefix.length() return false; char chars = prefix.toCharArray(); for(int i=0;i<

13、prefix.length();i+) if(valuesi!=charsi) return false; return true; /* * 判断suffix是否前缀子串 * param suffix * return */ public Boolean endsWith(MyString suffix) if(values.length<suffix.length() return false; char chars = suffix.toCharArray(); int i = this.length()-1; for(int j=suffix.length()-1;j>=0

14、;j-) if(valuesi!=charsj) return false; i-; return true; Override public String toString() StringBuffer stringBuffer = new StringBuffer(); for(int i=0;i<values.length;i+) stringBuffer.append(valuesi); return stringBuffer.toString(); 2. 统计在一个串中各字符的出现次数。源代码：测试实例： str1=“Good morning!” str2=“Shanghai

15、2010”粘贴测试结果：package Ex4.Ex4_2;import java.util.HashMap;import java.util.Map;/* * Created by 74062 on 2017/3/27. */public class Test public static void main(String args) System.out.println(count("Good morning!"); public static Map count(String string) Map<Character,Integer> characterI

16、ntegerMap = new HashMap<Character,Integer>(); for(int i=0;i<string.length();i+) Character character = string.charAt(i); if(characterIntegerMap.containsKey(character) characterIntegerMap.put(character,characterIntegerMap.get(character)+1); else characterIntegerMap.put(character,1); return ch

17、aracterIntegerMap; 3. 找出两个字符串中所有共同的字符。源代码：package Ex4.Ex4_3;import java.util.ArrayList;import java.util.HashSet;import java.util.List;import java.util.Set;/* * Created by 74062 on 2017/3/29. */public class Test public static List<Character> search(String string1, String string2) Set<Charact

18、er> set2 = new HashSet<Character>(); Set<Character> set1 = new HashSet<Character>(); /先统计两个字符串中出现的字符 for(int i =0;i<string1.length();i+) set1.add(string1.charAt(i); for(int i =0;i<string2.length();i+) set2.add(string2.charAt(i); Character chars1 = (Character) set1.toArray(

19、); Character chars2 = (Character) set2.toArray(); List<Character> result = new ArrayList<Character>(); /从出现的字符中作比较查出重复的字符串 for(int i=0;i<chars1.length;i+) for(int j=0;j<chars2.length;j+) if(chars1i = chars2j) result.add(Character) chars1i); return result; public static void main(String args) System.out.println(search("abcdefghl","hello world"); 粘贴测试结果：4. 判断一个字符串是否为一个E-mail地址。源代码：pa