how to say parameter can be null 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
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();