Clash Royale CLAN TAG#URR8PPP

What will happen if a string's value is set to an expression including an object?

I wonder what functions will be called if a string's value contains an object?

For example:

public class A

A a;
String str = "Hello" + a;


Does it also call String.valueOf(Object) as System.out.println() does?

String.valueOf(Object)

System.out.println()

1 Answer
1

See jls 15.18.1. String Concatenation Operator +:

If only one operand expression is of type String, then string
conversion (§5.1.11) is performed on the other operand to produce a
string at run time.

and jls 5.1.11. String Conversion:

If the reference is null, it is converted to the string "null" (four
ASCII characters n, u, l, l).

Otherwise, the conversion is performed as if by an invocation of the
toString method of the referenced object with no arguments; but if the
result of invoking the toString method is null, then the string "null"
is used instead.

The toString method is defined by the primordial class Object
(§4.3.2). Many classes override it, notably Boolean, Character,
Integer, Long, Float, Double, and String.

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