Java隐式转换函数参数

Question

Is it possible to automatically cast an integer to an object when passing it as function parameter? i have this function prototype:

public void aggiungiA(Nodo x)

Nodo has his own constructor with an integer parameter. Now, What i want do is:

aggiungiA(5);

with an implicit cast. is there anyway to do it?

Answer 1

There are no implicit casts via constructor invocations in java. You'll have to explicitly call the constructor - either from the caller, or by overloading the method:

public class MyClass {
    public void aggiungiA(int i) {
        aggiungiA(new Nodo(i));
    }

    public void aggiungiA(Nodo x) {
        // Do something with X
    }
}

Answer 2

In addition to @Mureinik's answer, I guess you are coming from a C++ background where certain casts do happen automatically. In Java things are different - the only implisit casts are:

• Widening of numeric types in expressions. For example in long x = myLong + inInt myInt will be cast to a long before the addition of the two long values
• Primitive values to their object equivelent. For example an 'int' is automatically cast to 'Integer' and a 'boolean' can be automatically cast to a 'Boolean'. This is called autoboxing
• Boxed objects can be cast back to their privitive values. For example an 'Integer' can be cast to an 'int' or a 'Character' to a 'char'. As this is the opposite of the previous cast it is called auto unboxing.