Java Permutation and Combination of boolean flags

Question

I have some boolean variables which will be passed as arguments

boolean var1;
boolean var2;
boolean var3;
boolean var4;

Depending on these variables, I have to code something like this

if (var1 && !var2 && !var3 && !var4) {
  //do something
}
elsif (var1 && var2 && !var3 && !var4) {
  //do something
}

. . . and so on.. using all the possible combinations. I can do this using if-else statement. Need to know is there some better approach. Thanks in advance.

Answer 1

Build a bit pattern out of the four boolean arguments, e.g. 0110 means var1 = false, var2 = true, var3 = true and var4 = false.

Then you can use the switch construct on the generated numbers.

int b = (var1 ? 8 : 0) | (var2 ? 4 : 0) | (var3 ? 2 : 0) | (var4 ? 1 : 0);
switch(b) {
   case 0:
      ...
   case 1:
      ...
}

Answer 2

I don't think there is a better approach. It depends on your code paths. If you really need 2*2*2*2 code paths, you will need to write that code somewhere. Either you make a big if-else block like you suggest, or you find another way to point to an implementation based on your flags (strategy pattern, switch, ..).