Object Creation JAVA

Question

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What is the difference between “text” and new String(“text”) in Java?

Please explain the brief and detailed difference between following 2 statements:

String a= "somevalue";
String b = new String("somevalue");

I know that 2nd statement creates and provide memory to String Object b in heap. But why object a doesn't get memory and its still allowed to operate on string methods.

score 3 · Accepted Answer · answered Sep 06 '12 at 09:42

3

a and b are references to Objects, not Objects.

When you do a = b; it doesn't copy the Object, it copies a reference to an Object.

A String has a char[] inside it which is another object.

a gets an reference to an existing object so it may not need any extra memory.

b get a reference to a newly created object so that requires more memory.

its still allowed to operate on string methods.

This has nothing to do with how the object was created.

answered Sep 06 '12 at 09:42

Peter Lawrey

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thank you @Peter. i want to add something. You should use `a` if you know object before creating, but use `b` in opposite case. – Dmitry Zagorulkin Sep 06 '12 at 09:45
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@ZagorulkinDmitry: b should NEVER be used. It makes no sense to create a copy of an immutable object. It only wastes memory and CPU cycles. – JB Nizet Sep 06 '12 at 13:46
@JBNizet Unless the `char[]` which backs the String is excessive in which case you need to take a copy of the bit you want. ;) – Peter Lawrey Sep 06 '12 at 13:54

score 3 · Answer 2 · answered Sep 06 '12 at 09:42

The first affects the literal String object "somvalue" to variable a. This literal String object is cached in a pool, as all literal Strings.

The second creates a new instance of empty String. Since String instances are immutable, it's equivalent to String b = "";, except it instantiates a new object for nothing.

Object Creation JAVA

2 Answers2