Remove Duplicate Character from String in java

public class RemoveDuplicateCharacter {

public static void main(String[] args) {

String s="hello";
String s1="";

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

if(s1.indexOf(s.charAt(i))==-1)
{
s1+=s.charAt(i);
}
}
System.out.println(s1);
}

}