String Class intern method

[Faraz Alig]

Hi,

Just wanted to know what is the difference in the below line of code.

Suppose I have two objects of the type String ff and cc. In one of the code I use the below line of code

ff = cc;

and at other place I used

String ff = cc.intern();

Thanks in advance!!!
Faraz

[marc weber]

Faraz Alig wrote:... Suppose I have two objects of the type String ff and cc...

You have two variables, but it's not clear whether you actually have two objects. That depends on how the Strings are created.

According to the API documentation...

When the intern method is invoked, if the pool already contains a string equal to this String object as determined by the equals(Object) method, then the string from the pool is returned. Otherwise, this String object is added to the pool and a reference to this String object is returned.

For more about the string pool, see Strings Literally.

[marc weber]

class TestStringObjects {
  public static void main(String[] args) {
    String literal1 = "alpha";
    String literal2 = "alpha";
    System.out.println("Literals point to same object: " + (literal1 == literal2));

    String newStr1 = new String("alpha");
    String newStr2 = new String("alpha");
    System.out.println("New strings point to same object: " + (newStr1 == newStr2));

    System.out.println("Literal same as uninterned new: " + (literal1 == newStr1));
    System.out.println("Literal same as interned new: " + (literal1 == newStr1.intern()));
  }
}

[Yogesh Gnanapraksam]

Here is the output of the program posted by marc

Literals point to same object: true
New strings point to same object: false
Literal same as uninterned new: false
Literal same as interned new: true

When we create a string object using new it always creates a new object even if an identical object exists.

Thanks
Yogi