String  str1  =  "nihaoksdoksad "; 
 String  str2  =  "ok "; 
 int  total  =  0; 
 for  (String  tmp  =  str1;  tmp  !=  null&&tmp.length()> =str2.length();){ 
  if(tmp.indexOf(str2)  ==  0){ 
    total  ++; 
  } 
  tmp  =  tmp.substring(1); 
} 
System.out.println(str1+ "中含有 "+total+ "个 "+str2);

String  str1  =  "nihaokokosdokosad "; 
String  str2  =  "oko "; 
int  total  =  0; 
for  (String  tmp  =  str1;  tmp  !=  null&&tmp.length()> =str2.length();){ 
  if(tmp.indexOf(str2)  ==  0){ 
    total  ++; 
    tmp  =  tmp.substring(str2.length()); 
  }else{ 
    tmp  =  tmp.substring(1); 
  } 
} 
System.out.println(str1+ "中含有 "+total+ "个 "+str2);

String  str1  =  "nihaoksdoksad "; 
char  []c=str1.toCharArray(); 
int  total=0; 
for(int  i=0;i <c.length-1;i++) 
if(c[i]== 'o '&&c[i+1]== 'k ') 
total++; 
System.out.println(str1+ "中含有 "+total+ "个ok ");