Hello how to use switch loop in my android project ? I want to use Android 2.1

I need JRE 1.7, but I want to use Android 2.1

I use loop like this:

switch ((CHAR[Math.abs(intGen.nextInt()%2)])) {
    case "+":
        result = random2 + random3;
        break;
    case "-":
        result = random2 + random3;
        break;
} 

LogCat:

Cannot switch on a value of type String for source level below 1.7. Only convertible int values or enum variables are permitted