[Java] Randomly choosing array elements

So I have a program that generates random passwords using the ASCII values from 33 - 126, but there are certain ones I don't want to use (34, 35, 100, whatever)

What I initially did was use Math.random to generate a number between 33 - 126, then an if statement to make sure the generated password didn't contain any of the forbidden characters.

This is extremely inefficient and shitty, and I would much rather make it so I have an array of all the valid ASCII values, and it randomly chooses, say, 6 of them and throws them in to another char array to hold the password.

I am quite new at this, so I don't really know how to do that.

This is the for loop that I am currently using to pick values between 33 and 126:

for(int i = 0; i < tempPass.length; i++)
{
   tempPass[i] = (char)((int)(94 * Math.random()) + 33);
}

How do I change this to pick values from 0 to 76 (the elements of the valid char array)??