Using BitSet to to judge if string a contains all letters in string b

package algorithm;

import java.util.BitSet;

public class BitSetStudy {

static char a[] ={'a','b','c','d','e','f','j'};
static char b[] ={'e','f','g'};

public static boolean isContain(char[] a,char[] b){
BitSet bitSet = new BitSet();
boolean isContain = true;
for(char c : a){
bitSet.set(c);
}
for(char c : b){
if(!bitSet.get(c)){
isContain = false;
}
}
return isContain;
}

public static void main(String[] args) {
boolean result = isContain(a,b);
System.out.println(result);
}
}