Complete the task by querying the string class in the Java API

Package com. String;public class a {    public static void main (String[]  args)  {        String str =  "This is  a test of java ";         t1 (str);//  The static method can call         t2 (str) directly;       &NBSP;&NBSP;T3 (str);         t4 (str);      &NBSP;&NBSP;&NBSP;T5 (str); &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;T6 (str);         t8 ("123321");     }    // 1. Counts the number of occurrences of the letter S in the string     public static void t1 (STRING&NBSP;STR)  {         int num = 0;//  Define a counter          for  (INT&NBSp;i = 0; i < str.length ();  i++)  {             char ch = str.charat (i);//  get the character of the current position              if  (ch ==  ' s ')  {                 num++;//  If there is a s, counter +1             }         }        system.out.println ("string has:"  + num +   "S");     }    // 2. Remove substring "test"      Public static void t2 (STRING&NBSP;STR)  {         Int beginindex = str.indexof ("test") the position of the;//  substring first appears          int endindex = beginindex + 4;        string s  = str.substring (Beginindex, endindex);         System.out.println (s);     }    // 3. Copy this string to a character array in a variety of ways char[] &NBSP;&NBSP;&NBSP;&NBSP;PUBLIC&NBSP;STATIC&NBSP;VOID&NBSP;T3 (STRING&NBSP;STR)  {         //  method One: Char[] ch=str.tochararray ();         //  Method Two:        char[] ch = new  Char[str.length ()];//  defines an array         for  (int i =  0; i < str.length ();  i++)  {             ch[i] = str.charat (i);//  remove characters from a specific position to the array          }         system.out.println (ch.length +  ","  + str.length ());//  The array length is consistent with the string length, which indicates that replication succeeded     }    // 4. capitalizes the first letter of each word in a string,  Output to the console. &NBSP;&NBSP;&NBSP;&NBSP;PUBLIC&NBSP;STATIC&NBSP;VOID&NBSP;T4 (STRING&NBSP;STR)  {         string[] ss = str.split (" ");//  the word with a space and gets an array of strings          String result =  "";         for  (Int i = 0; i < str.length ();  i++)  {             char c = ss[i].charat (0);//   Remove the first letter of the word             string s =  string.valueof (c);//  convert character to string   or a-97,a-65             String S1 = s.touppercase ();//  into uppercase              system.out.println (S1);             string  s2 = s1 + ss[i].substring (1);// ss[i].substring (1): intercepts the remaining strings in each word except for the first letter              result = result + s2  +  " ";        }       &NBSP;&NBSP;SYSTEM.OUT.PRINTLN (result);     }    // 5. To implement the reverse output of the string &NBSP;&NBSP;&NBSP;&NBSP;PUBLIC&NBSP;STATIC&NBSP;VOID&NBSP;T5 (STRING&NBSP;STR)  {         string s = new stringbuffer (str). reverse (). ToString ();//  After the anonymous object call reverse method reverses, it becomes a string         system.out.println (s);     }   &Nbsp;// 6. Converting this string to an array of strings requires that each array element be a meaningful English word and output to the console     public static  VOID&NBSP;T6 (STRING&NBSP;STR)  {        string[] ss =  str.split (" ");//  separated by spaces         for  (int i  = 0; i < str.length ();  i++)  {             //  judge current Ss[i] is not a valid word:             boolean b = true;//  Define flag amount B, default B valid              for  (Int j = 0; j < str.length ();  j++)  {                 if  (!) ( (Ss[i].charat (j)  >=  ' A '  && ss[i].charat (j)  <=  ' z ')  | |   (SS[I]&NBSP;&Nbsp;                       .charat (j)  >=  ' A '  && ss[i].charat (j)  <=   ' Z '))  {                     b = false;// ss[i] is not a word, as long as one does not jump out of the loop                      break;                 }             }             if  (b)  {                 system.out.println (Ss[i]);             }  &nbsP;     }        system.out.println ("--------- -");     }    // 8. Determine if the input string is a palindrome (such as  12344321, ABCCBA is a palindrome   112233 not)--the same     public static void t8 after folding (STRING&NBSP;STR)  {         //method Three: Reverse the string, and the same as the original string, then a palindrome          //method Two: The first half and the last half of the string to make a fuss         String s1 =  Str.substring (0, str.length ()  / 2);//  first half string          string s2 = str.substring (Str.length ()  / 2 +  (Str.length ()  % &NBSP;2),                 Str.length ());//  the latter half of the string         string s3 = new  stringbuffer (S2). Reverse (). toString ();         if  (S1.equals (S3))  {             system.out.println ("true");         }    }}      // 7. Implements the word flashback output of the string. (i.e. output Siht si a tset fo avaj).

Complete the task by querying the string class in the Java API