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doubt about ==

 
Greenhorn
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Integer i1 = new Integer(2);
Integer i2 = new Integer(2);
System.out.println(i1 == i2); // FALSE

Integer j1 = 2;
Integer j2 = 2;
System.out.println(j1 == j2); // TRUE

Integer k1 = 150;
Integer k2 = 150;
System.out.println(k1 == k2); // FALSE
Can somebody explain why is this happening?

Integer jj1 = 127;
Integer jj2 = 127;
System.out.println(jj1 == jj2); // TRUE

int jjj1 = 127;
Integer jjj2 = 127;
System.out.println(jjj1 == jjj2); // TRUE

Integer kk1 = 128;
Integer kk2 = 128;
System.out.println(kk1 == kk2); // FALSE
Can somebody explain why is this happening?

Integer kkk1 = 128;
int kkk2 = 128;
System.out.println(kkk1 == kkk2); // TRUE

Integer w1 = -128;
Integer w2 = -128;
System.out.println(w1 == w2); // TRUE

Integer m1 = -129;
Integer m2 = -129;
System.out.println(m1 == m2); // FALSE

int mm1 = -129;
Integer mm2 = -129;
System.out.println(mm1 == mm2); // TRUE
Thanks
 
Ranch Hand
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Hi,
When you write something like :
Integer v1 = val;
Integer v2 = val;

For Integer and Short :
v1 == v2 is true IF -128 <= val <= +127

For Character :
v1 == v2 is true IF 0 <= val <= +127

This is always true for Boolean and Byte

If you have the K&B you can read that in Chapter 5, page 236
 
Ranch Hand
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Hello,
Can somebody explain why this is true?



thanks
 
Ranch Hand
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Originally posted by Alexsandra Carvalho:
System.out.println(kkk1 == kkk2); // TRUE[/CODE]

This is equivalent to
System.out.println(kkk1.intValue() == kkk2);
 
Alexsandra Carvalho
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Thanks Manfred. I have read K&B but I need study much more about autoboxing and Wrapper Classes.
Can you indicate some docs?
thanks
 
Manfred Klug
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Originally posted by Alexsandra Carvalho:
Can you indicate some docs?

Sorry, no recommendations. But one good way to remember things is to answer questions.
 
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