Strings doubt

[Radha Kamesh]

hi friends,

Can anyone explain why this produces an output of "not Equal" while
instead of if(" String ".trim() == "String") , we replace if(" String" == "String") we get an output of "equal"... what happens internally?

public class equality {
public static void main(String[] args) {

 if(" String ".trim() == "String")
    System.out.println("Equal");
else
    System.out.println("Not Equal");
 
}

Thanks in advance
[ September 04, 2007: Message edited by: Radha Kamesh ]

[vivekkumar sharma]

Hi

Both of these wonot work.
to conmpare string use equals method.

hope this helps

[krishnamoorthy kitcha]

Hi Radha Kamesh


In the first string have empty space, Both the strings are not equal.

Try to yourself , Remove the empty space before and after of the string.

It shows the equal otherwise , shows the UnEqual.

Here check with content of the Object.

[ranikkarasu mano]

== operator checks if both object references refer to the same memory location eg: if (a==b) it means it verifies whether both a and b refer to the same location in memory.

equals() if for content comparison.

[Mack Stevens]

HI........
The functionality of "==" operator and equals() method is different.

1)."==":returns true if both the references are pointing to the same object.
2).equals():returns true if both the references point to objects that are equal in their context(Value).

So in your question trim() method is creating another object and is being applied to "==" operator which will return false.

when you apply equals() method it will return true.

So follows the output.
..............................................................
Regards,
Mack

[Jianghu Li]

public class Test090302 {
public static void main(String[] args) {
 
String str = " String ".trim();
String str2 = "String";
if (str == str2)
System.out.println("Equal");
else
System.out.println("Not Equal");

String str3 = "temp";
String str4 = "temp";
if (str3 == str4)
System.out.println("Equal");
else
System.out.println("Not Equal");
 

}
}    

Output is：

 Not Equal
Equal   

Can anyone explain this?
3x...

[ahmed yehia]

    
String str3 = "temp";
String str4 = "temp";
if (str3 == str4)
  System.out.println("Equal");
else
  System.out.println("Not Equal");

prints: Equal

String objects str3 and str4 are both created using string literals thus created in the String literal pool, and two objects created using the same literal will refer to the same object in the pool.