Difference

[vineet walia]

Anybody please tell me is there is any difference if we create primitive object by these two ways
Integer i1= 14;
Integer i2= new Integer (14);


and also explain this two line code also

Integer a= 15;
Integer b=15;
system.out.println(a==b);  // true

Integer a= new Integer(15);
Integer b=new Integer(15);
system.out.println(a==b);  // false

Integer a= 200;
Integer b=200;
system.out.println(a==b);  // false

[Sebastian Janisch]

Please choose an appropriate title for your question that explains what problem you are facing.

Integer i = 15;

15 is a primitive that is autoboxed to an Integer object. Behind the scenes however, the compiler does not invoke new Integer(15) but Integer.valueOf(15).

The difference between the two is that the valueOf method works with an internal cache that ranges from -127 - 128, hence two objects created with valueOf that are in that range will pass the == test.

new Integer ALWAYS instantiates a new object, regardless if the number is 1, 5 or 123131.

[vineet walia]

please
any more

[vineet walia]

Sebastian Janisch wrote:Please choose an appropriate title for your question that explains what problem you are facing.

Integer i = 15;

15 is a primitive that is autoboxed to an Integer object. Behind the scenes however, the compiler does not invoke new Integer(15) but Integer.valueOf(15).

The difference between the two is that the valueOf method works with an internal cache that ranges from -127 - 128, hence two objects created with valueOf that are in that range will pass the == test.

new Integer ALWAYS instantiates a new object, regardless if the number is 1, 5 or 123131.

Integer i1=Integer.valueOf("15");
	Integer i2=Integer.valueOf("15");
	System.out.println(i1==i2);

// false
can you explain why its not true this time

[Henry Wong]

// false
can you explain why its not true this time

Only the valueOf() method, that takes an int, and used by autoboxing, uses the integer cache.

Henry

[Sebastian Janisch]

Because you are giving it a String and not a primitive int, hence another mechanism of creating the Integer object is in force.

Use Integer.parseInt() for Strings

[karthick chinnathambi]

if you create an Integer object through auto-boxing they are stored in a special place in the heap.......

just like in the case of String objects created using double quotes("").....

the following are the data-types and their ranges which when created through auto-boxing with same type and value will point to same object on heap......

1)Boolean
2)Byte
3)Short and Integer from -128 to 127
4)Character....

[vineet walia]

thanks Sebastian Janisch and Henry Wong

[Jarred Olson]

vineet walia wrote:Anybody please tell me is there is any difference if we create primitive object by these two ways
Integer i1= 14;
Integer i2= new Integer (14);


and also explain this two line code also

Integer a= 15;
Integer b=15;
system.out.println(a==b);  // true

Integer a= new Integer(15);
Integer b=new Integer(15);
system.out.println(a==b);  // false

Integer a= 200;
Integer b=200;
system.out.println(a==b);  // false

Also remember that when comparing two objects you should use the .equals() method when comparing value equality. So try the following:

 Integer a = 200;
Integer b = 200;
System.out.println(a==b); //false
System.out.println(a.equals(b)); //true

[Himalay Majumdar]

Integer i1 = Integer.valueOf(15);
Integer i2= Integer.valueOf(15);
System.out.println(i1==i2); //is true

Integer i1 = Integer.valueOf(127);
Integer i2= Integer.valueOf(127);
System.out.println(i1==i2); //true

Integer i1 = Integer.valueOf(-128);
Integer i2= Integer.valueOf(-128);
System.out.println(i1==i2); //true

The range is actually -128 to 127. If the value falls outside the range valueOf doesnt work..rather new objects are created..making them unequal.
HTH

[Henry Wong]

The range is actually -128 to 127. If the value it fall outside the range valueOf doesnt work..rather new objects are created..making them unequal.

This is a nitpick... The java specification merely states the range that must be cached. It does *not* state what happens to values that fall out of the range. It is perfectly valid to have a JVM implementation, that caches a larger range, and hence, have the same object after autoboxing.

Henry