[JAVA] TDD study # 4 (July 16th, 2020)

New knowledge

toString method

public String toString()
//Returns a string representation of the object

Expression Creates and calls a "new" Expression method using the specified value of the specified object.


Only constants and methods can be defined.

interface AAA {
    int A1 = 1;
    int A2 = 2;

    void BBB();

Use ʻimplements` to implement an interface in a class.

class abc implements AAA{

instanceof operator

Dynamically determine the type of an object. An object ・ Is it an instance of a certain class? -Is it an instance of a child class of a certain class? Is it an instance that implements a specific interface?

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