Java optional parameters

    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");

Source: stackoverflow.com

Java how to make a parameter optional

void foo(String a, Optional<Integer> bOpt) {
    Integer b = bOpt.isPresent() ? bOpt.get() : 0;
    //...
}

foo("a", Optional.of(2));
foo("a", Optional.<Integer>absent());

Source: stackoverflow.com

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);

Source: stackoverflow.com

Java how to make a parameter optional

void foo(Map<String, Object> parameters) {
    String a = ""; 
    Integer b = 0;
    if (parameters.containsKey("a")) { 
        if (!(parameters.get("a") instanceof Integer)) { 
            throw new IllegalArgumentException("...");
        }
        a = (Integer)parameters.get("a");
    }
    if (parameters.containsKey("b")) { 
        //... 
    }
    //...
}

foo(ImmutableMap.<String, Object>of(
    "a", "a",
    "b", 2, 
    "d", "value"));

Source: stackoverflow.com

Java how to make a parameter optional

 class Foo {
     private final String a; 
     private final Integer b;

     Foo(String a, Integer b) {
       this.a = a;
       this.b = b;
     }

     //...
 }

 class FooBuilder {
   private String a = ""; 
   private Integer b = 0;

   FooBuilder setA(String a) {
     this.a = a;
     return this;
   }

   FooBuilder setB(Integer b) {
     this.b = b;
     return this;
   }

   Foo build() {
     return new Foo(a, b);
   }
 }

 Foo foo = new FooBuilder().setA("a").build();

Source: stackoverflow.com

Java optional parameters

@SuppressWarnings("unchecked")
static <T> T getParm(Map<String, Object> map, String key, T defaultValue) {
  return (map.containsKey(key)) ? (T) map.get(key) : defaultValue;
}

void foo(Map<String, Object> parameters) {
  String a = getParm(parameters, "a", "");
  int b = getParm(parameters, "b", 0);
  // d = ...
}

foo(Map.of("a","a",  "b",2,  "d","value"));

-1

Source: stackoverflow.com

Similar codes

8 votes239 views3 answers
How to create a java txt file from programm
Java
12 votes254 views2 answers
Java date time
Java
0 vote260 views1 answer
Transparent border of jtextfield in java
Java
0 vote253 views1 answer
Javafx edit list
Java
0 vote276 views1 answer
Hide steam games from friends
Java
0 vote285 views1 answer
List of tuple to map + jpa
Java
0 vote263 views1 answer
Precision java
Java
-1 vote270 views2 answers
Running Sum of 1d Array
Java
1 vote295 views1 answer
Jda embed message
Java
0 vote269 views2 answers
Write code to declare an array that will hold calendar months (.e. January to December) java
Java