Java でa == 1 && a == 2 && a == 3やってみた

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public class Main {

    public static void main(String[] args) {
        
        MyInt a = new MyInt(1);

        if (a.equals(1) && a.equals(2) && a.equals(3)) {
            System.out.println("true");
        } else {
            System.out.println("false");
        }    
    }
}

class MyInt {
    int i;

    public MyInt(int i) {
        this.i = i;
    }

    @Override
    public boolean equals(Object i) {
        return (int)i == this.i++;
    }
}

1
2
3

$ javac Main.java
$ java Main
true