怎么判断一个字符串中是否包含另一个字符串

如何判断一个字符串中是否包含另一个字符串？

String   a   =   "HelloWorld";
String   b   =   "oWor";

如何符合判断a中是否包含b？

 

如果  a.indexOf(b)> =0    或者       a.indexOf(b)!=-1  就说明包含 

 

 

public   class   Text4   { 
        
        public   static   void   main   (String[]   args)   {
        String   a   =   "HelloWorld";
        String   b   =   "oWor";

         System.out.println(a.indexOf(b));
        }
       
}

输出   4    

 

如果不包含输入为   -1

public   int   indexOf(String   str)
Returns   the   index   within   this   string   of   the   first   occurrence   of   the   specified   substring.   The   integer   returned   is   the   smallest   value   k   such   that:  
  this.startsWith(str,   k)
 
is   true.  

Parameters:
str   -   any   string.  
Returns:
if   the   string   argument   occurs   as   a   substring   within   this   object,   then   the   index   of   the   first   character   of   the   first   such   substring   is   returned;   if   it   does   not   occur   as   a   substring,   -1   is   returned.