params 2 options java code example

Example 1: java how to make a parameter optional

void foo(String a, Object... b) {
    Integer b1 = 0;
    String b2 = "";
    if (b.length > 0) {
      if (!(b[0] instanceof Integer)) { 
          throw new IllegalArgumentException("...");
      }
      b1 = (Integer)b[0];
    }
    if (b.length > 1) {
        if (!(b[1] instanceof String)) { 
            throw new IllegalArgumentException("...");
        }
        b2 = (String)b[1];
        //...
    }
    //...
}

foo("a");
foo("a", 1);
foo("a", 1, "b2");

Example 2: java how to make a parameter optional

void foo(String a, Integer... b) {
    Integer b1 = b.length > 0 ? b[0] : 0;
    Integer b2 = b.length > 1 ? b[1] : 0;
    //...
}

foo("a");
foo("a", 1, 2);