Simple programming questions about string __string

One, invert the string

package string;

        public class Reverse {public static void main (string[] args) {String S1 = ' abc DEFG WF ';
        Reverse string s2 = "" With string-character array;
        Char[] cs = S1.tochararray ();
        for (int i = cs.length-1 i >= 0; i--) {s2 = s2 + cs[i];
        System.out.println ("Method one reverse operation is:" + s2);
        Using StringBuffer's reverse () method to realize inversion stringbuffer sb = new StringBuffer (S1);
        StringBuffer SB2 = Sb.reverse ();
        System.out.println ("Method two reverse operation is:" + SB2);
        Inversion String S3=myreverse (S1) is implemented using reverse storage;


    System.out.println ("method three evils after the operation is:" + S3);  
        public static string Myreverse (String str) {char[] arr = new char[str.length ()];  
        int pos = Str.length ();  
        for (int x=0; x<str.length (); x + +) {Arr[x] = Str.charat (--pos);  
        str = string.copyvalueof (arr);  
    return str; }  
}

Output:

Method A reverse operation is: FW gfed   CBA
method Two reverse operation: FW gfed   CBA
method Three evils after operation: FW gfed   CBA

Two, the realization goes to the string two ends space function

Package string;

public class Trime {public
    static void Main (string[] args) {
        String str1 = "   dwwg dwg  wfg   ";
        Using the String class own method to remove both ends space
        string str2 = Str1.trim ();
        System.err.println ("Method One" +str2);
        Custom method to remove both ends space
        String Str3=mytrim (str1);
        System.err.println ("Method Two" +STR3);

    }

    public static string Mytrim (String str) {
        int start = 0, end = Str.length ()-1;
        while (Start <= end && Str.charat (start) = = ")
            start++;
        While (the start <= end && Str.charat (end) = = ")
            end--;
        Return str.substring (Start, end + 1);
    }

Output:

Method one DWWG dwg  wfg
method two DWWG dwg  WFG

Gets the number of times a string appears in another string and returns the starting index

Package string;

public class GetCount {public

    static void Main (string[] args) {
        String str = "sshelloworldhellojavahellojsp"; 
  system.out.println ("count=" + getsubcount (str, "Hello"));
    }


    public static int Getsubcount (string str, string key) {
        int count = 0;
        int index = 0;
        while (index = Str.indexof (key, index))!=-1) {
            System.out.println ("index=" + index);
            index = index + key.length ();
            count++;
        }
        return count;
    }

}

index=2
index=12
index=21
count=3

IndexOf returns the index value at the beginning of the substring in the long string, and returns 1.

The reverse of an English sentence

package string; import Java.util.Scanner; public class Reverse02 {public static string Reversewords (string sentence) {StringBuilder sb = new Stringbu
        Ilder (Sentence.length () + 1);
        string[] Words = Sentence.split ("");
        for (int i = words.length-1 i >= 0; i--) {sb.append (Words[i]). Append (");
        } sb.setlength (Sb.length ()-1);
    return sb.tostring ();
        public static void Main (string[] args) {Scanner in = new Scanner (system.in);
        Holds the input string System.out.println ("Input test Case number n:");
        string[] input = new string[in.nextint ()];

        In.nextline ();
        for (int i = 0; i < input.length i++) {Input[i] = In.nextline ();
        }//output in reverse order after the English string System.out.println ("Output is:");
        for (String s:input) {System.out.println (Reversewords (s)); }
    }
}

Enter test Case number N:
2
Hello world!
I love you?
The output is:
world! Hello and love
i

Four, delete the most occurrences of characters in a string

Package string;
Import Java.util.HashMap;
Import Java.util.Map;

Import Java.util.Set;
        public class Delmost {public static void main (string[] args) {String str = "AASSDFSCFW";
        Map<character, integer> map = new Hashmap<character, integer> ();
        char[] box = Str.tochararray ();
            for (char ch:box) {Integer i = map.get (CH);
            if (i = = null) {map.put (ch, 1);
            else {map.put (ch, i + 1);
        }//Create map key value pair Integer max = 0;
        set<character> set = Map.keyset ();
            for (Character Key:set) {Integer j = map.get (key);
            if (Max < j) {max = J; }///The maximum number of times is passed to Max for (Character key:set) {if (Map.get (key) = max) {str
            = Str.replaceall (Key.tostring (), "");

    } System.out.println (str);
 }
}

Aadfcfw

Enter a line of characters to count English letters, numbers and spaces.

Package string;

Import Java.util.Scanner;

public class Tongji {public
    static void Main (string[] args) {
        int eng=0,num=0,kong=0,elsel=0;
        Scanner sc=new Scanner (system.in);
        String str=sc.nextline ();
        Char[] Ch=null;
        Ch=str.tochararray ();
        for (char c:ch) {
            if (c>= ' 0 ' &&c<= ' 9 ') {
                num++;
            } else if ((c>= ' a ' &&c<= ' z ') | | (c>= ' A ' &&c<= ' Z ')) {
                eng++;
            } else if (c== ') {
                kong++
            } else{
            elsel++
            }
        }
        SYSTEM.OUT.PRINTLN ("Letter has" +eng);
        SYSTEM.OUT.PRINTLN ("number has" +num);
        SYSTEM.OUT.PRINTLN ("Space has" +kong);
        System.out.println ("other" +elsel);
    }

Hello World 378nihao has
3
spaces and 2
other 0