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    05_tombok.pps


class C {}


new C()

double d = 13.0;
double d = 13;

(double)13 == 13.0
13 == 13.0

float f = 13.0;     // nem
int   i = 13.0;     // nem

float f = (float)13.0;     // nem
int   i = (int)13.235;     // nem


352.equals(325);

"asdbdsa" == "asdbdsa"
new X() == new X()


class X
{
    @Override       // annotáció
    public boolean equals()

}


new Date(.....).equals("asdbgasd");
new Date(.....).equals(null);
new Date(.....).equals(new ArrayList());

new Date(1,2,3).equals("1-2-3");
"1-2-3".equals(new Date(1,2,3));


class Sorszamozott 
{
    static int staticSorszam = 1;
    int sorszam = ++staticSorszam;


    public boolean equals(Object o) {
        if (this == o)   return true;
        if (!(o instanceof Sorszamozott))  return false;

        Sorszamozott s = (Sorszamozott)o;

        return sorszam == s.sorszam;
    }

    public int hashCode() { return sorszam; }
}

new Sorszamozott().equals(new Sorszamozott());

Sorszamozott s = new Sorszamozott();
s.equals(null);
s.equals(s);



immutable


String s = "";
for (int i = 0; i < 10000; ++i)   s += "a";

a
aa
aaa
aaaa
aaaaa
..................
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

1000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
                                                                                         80


StringBuilder sb = new StringBuilder();
for (int i = 0; i < 10000; ++i)   sb.append("a");




420  424  428  432
---- ---- ---- ---- ---- ----
#0   #1   #2   ...

420 + idx * 4
420 + 1000000 * 4 = 1000420


new int[3][2]

-(1) -(2) -(3)
       (2) ---- ----     (3) ---- ----
                    (1) ---- ----

nem Java: int[3, 2]

1,1  1,2  1,3  2,1  2,2  2,3
---- ---- ---- ---- ---- ----

420 + idx1 * (belső tömb hossza) + idx2 * (elem hossza)