CC1.1

public boolean isUnique(String line) {
	int[] count = new int[256];
	for(int i = 0; i < line.length(); i++)	
	count[line.charAt(i)]++;
	for(int i = 0; i < 256; i++) {
	    if(count[i] > 1)
			return false;
	}
	return true;
}

1. There are 2 for loops in your program. You can use only one to achieve the same goal.
2. You did not check the edge case when input is null.
3. You should return the result directly if the length of string is 0 or bigger than 256.