Programming algorithm base-2.1 using the string API

2.1 Using the String API

Strings are the most common type of java. And is a composite type

Strings are very often used, and their best APIs are familiar with documents.

Infer that there are no repeated characters in the string

String s = "abcdebxyz";

Infer that there are no repeated characters

/* Infer that there are no repeated characters in string s = "abcdebxyz"; infer that there are no repeated characters */package stringapi; public class Judgerepeatinstring {public    static void Main (string[] args) {       String s = "Abcdex ah yz";       Boolean judge = false;//Inference token, initialization is not repeated for             (int i=0;i<s.length (); i++) {//} first traversal of this string           char c = s.charat (i);// Get the character I-bit           if (S.lastindexof (c)!=i) {//Assume that the last occurrence of C in the string is the position of the character in the!=i              judge = true;//has repeated           }       }       SYSTEM.OUT.PRINTLN (judge);    }}

True

char	charAt(int index) Returns the value at the specified index char .
int	lastIndexOf(int ch) Returns the index of the specified character at the last occurrence in this string.

Shift Encryption

ASCII code + one number

The definition of a string cannot be changed.

The so-called change, is reborn into a new string

Assuming a large number of freshmen into new strings, there is great pressure on the computer

So consider turning the string into an array of char types. After the shift is encrypted, it becomes a string and can.

/* Shift-encrypted ASCII + A string of definitions is the so-called change that cannot be changed, is a new string of freshmen into the new string hypothesis, a large number of freshmen to the computer has a very large pressure, so consider the string into a char type array, shift encryption after the string. We can. *  /Package Stringapi, public class Movesecret {public    static void Main (string[] args) {       String s = "Where is Is my code Chinese very messy? ";       Char c[] = S.tochararray ();//The string is converted to a char array for       (int i=0;i<c.length;i++) {           c[i]++;       }             String s2 = new String (c),//The constructor of the string is referred to as the char array.
       SYSTEM.OUT.PRINTLN (s2);    }}

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char[]	toCharArray() Converts this string to a new character array.
String(char[] value) Assign a new one String . Causes it to represent the sequence of characters currently included in the character array parameter.

 

Infer

Infer if a full path name is in the C drive and is an. ini extension.

"C:\\xyz\\bak\\x.ini" composite standard

"Ccc\\ttt\\kk\\ini" is not

/* Inference infers whether a full pathname is in the C drive and is an. ini extension.
"C:\\xyz\\bak\\x.ini" composite Standard "Ccc\\ttt\\kk\\ini" is not  */package stringapi; public class Judgepath {public    static void Main (string[] args) {       //String s = "Ccc\\ttt\\kk\\ini";       String s = "C:\\xyz\\bak\\x.ini";       Boolean judge = false;        if (S.startswith ("c:\\") && s.endswith (". ini")) {//start with "c:\\" && End with ". ini"           judge = true;       }       SYSTEM.OUT.PRINTLN (judge);    }} True

boolean	startsWith(String prefix) Test whether this string starts with the specified prefix.
boolean	endsWith(String suffix) Tests whether this string ends with the specified suffix.

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Programming algorithm base-2.1 using the string API