我的代码出现错误：不兼容的类型：int无法转换为布尔线：6

Question

public int countHi(String str) 
{
  int hiCount = 0;
  for (int i=0; i < str.length()-1; i++)
 {
   if (str.indexOf("hi"))
   {
     hiCount++;
     i++;
   }
 }
return hi;
} 

Been trying to get this code for an assignment done, yet I keep getting the error (title) constantly. I'm not the brightest, could anyone help me? I'm trying to get the code to return the number of times "hi" is within the code.

Answer 1

String.indexOf returns in int : the index where the argument was found, or -1 if it wasn't found. It doesn't return a boolean value like you expected.

To check if "hi" was found, instead of writing:

if (str.indexOf("hi"))

You should write:

if (str.indexOf("hi") != -1)

Answer 2

Firstly, for the for loop in order to loop the whole length of the string it should be :

for (int i=0; i < str.length(); i++)

instead of str.length-1. If the str.length == 6 str.length-1. If the str.length == 6 , it will already loop from 0 - 5 as its iterating until i < str.length

Secondly, it needs to check for str.indexOf("hi") != -1 first in order to check what is the starting index that contains "hi". Then subsequently make a substring of the rest of the string and continue checking for if it contains "hi".

So your code should look more like :

public int countHi(String str)
{
  int hiCount = 0;
  int index = str.indexOf("hi");
  for (int i=0; i < str.length(); i++)
  {
    while(index != -1)
    {
      hiCount++;
      str = str.substring(index+1);
      index = str.indexOf("hi");
    }
  }
  return hiCount;
}