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javastringliteralspool
Cristian Balint
Cristian Balint

Reputation: 157

Java String Literal Pool

Let's say we have the following code

String x = new String("xyz");
String y = "abc";
x = x + y;

A friend of mine says that 4 objects are created in total, where I say that only 3 are created. Can someone explain what's going on in the background? I've read about String Literal Pool, but I can find an answer for this.

My explanation for the creation of the 3 object is as follows: one in the String Literal Pool at compile time ("abc"), and two at runtime on the heap ("abc" and x + y)

Upvotes: 0

Views: 216

Answers (4)

Sasikumar Murugesan
Sasikumar Murugesan

Reputation: 4520

Yes the code will create 4 objects

String x = new String("xyz"); // object#1 : xyz and Object #2: new String
String y = "abc";             // Object#3 : abc
x = x + y;                    // object#4 : xyzabc

Upvotes: 0

SubOptimal
SubOptimal

Reputation: 22973

4 objects are created as follow

// 1. "xyz" in the literal pool
// 2. a new String object which is a different object than "xyz" in the pool
String x = new String("xyz");

// 3. "abc" in the literal pool
String y = "abc";

// 4. new String object
x = x + y;

Upvotes: 2

nafas
nafas

Reputation: 5423

4 objects will be created.

String are unmodifiable so every time you concatenate them a new object will be created

in the case of "xyz" in new String("xyz"); you first create "xyz" object then pass it into a new object (String) so, there are two objects here

new String("xyz") <--there are two objects 
"abc"   <-- kinda obvious
x + y  <-- String are unmodifiable thus this is a new object

Upvotes: 2

Pavan Kumar K
Pavan Kumar K

Reputation: 1376

Actually.. String pool works when there are same values for both the strings.

For example, if we have String s1="abc" and s2="abc", then both s1 and s2 will point to same memory reference (or an object).

In the above case, 3 objects will be created

  1. for x varible on heap

  2. for y variable on stack

  3. for x+y expression on heap

Upvotes: 0

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