tostring() is implicitly called… how?

Question

In the following code, how is toString() is implicitly called?

class Payload {
    private int weight;
    public Payload (int w) {
        weig         


        

Answer 1

You're calling "p is " + p, which effectively is compiled to

new StringBuffer("p is").append(p)

This code calls p.toString() within .append() as p is Object.

Specified by:
http://docs.oracle.com/javase/7/docs/api/java/lang/StringBuffer.html#append(java.lang.Object)