String objects are immutable they can be shared. I do no get what this means...please help.

[Yaki Kumar]

"Strings are constant; their values cannot be changed after they are created. String buffers support mutable strings. Because String objects are immutable they can be shared. For example:

String str = "abc";

is equivalent to:

char data[] = {'a', 'b', 'c'};
String str = new String(data);
"
This is the description given in Java Doc by Sun.

I wish to know what this sharing refers to.
Thanks in advance.

[W. Joe Smith]

Sharing String has to do with the String pool. If I write the following:

  
String first = "car"
String second = "car"


  

While I created two Strings, they both point to the same String in the String pool, because Strings are immutable and will never change.

[appu sharma]

I cannt draw diagram here but i try .. for further refrence you can see chapter 6 of K&B


String class(Immutable)

1.String x="abc";
x.concat("def");
System.out.println("x= "+x);
//output is x= abc
/*Because no new assingment was made,
the new string ojbect created with the concat()
method was abandoned insatantly*/

2.String x="abc";
x=x.concat("def");
System.out.println("x= "+x);
//output is x= abcdef
/*we got a nice ne string out of the deal, but the
downsideis that the old string has been lost in string pool,
thus wasting memory*/

[appu sharma]

StringBuilder or StringBuffer (mutable)

 StringBuffer sb= new StringBuffer("abc");
ab.append('def");
System.out.println("sb = " +sb);        //output is "sb = abcdef"   

now i think you got your answer???

[j dam]

vinit sharma wrote:StringBuilder or StringBuffer (mutable)

 StringBuffer sb= new StringBuffer("abc");
ab.append('def");
System.out.println("sb = " +sb);        //output is "sb = abcdef"   

now i think you got your answer???

hi, the second poster already answered your question.

Java has temporary memory to store short strings. here is example:

String a = "abc"; String b ="abc";
if (JVM temporary memory has "abc") then (a and b always refer to the same object)