Example 1: 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());
Example 2: java how to make a parameter optional
void foo(String a, Integer b) {
}
void foo(String a) {
foo(a, 0);
}
foo("a", 2);
foo("a");
Example 3: java how to make a parameter optional
@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);
}
foo(Map.of("a","a", "b",2, "d","value"));
Example 4: 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 5: 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"));
Example 6: java how to make a parameter optional
void foo(String a, Integer b, Integer c) {
b = b != null ? b : 0;
c = c != null ? c : 0;
}
foo("a", null, 2);