Two string's which (I think) are identical do not return true when checking if the same

Question

I have two strings, one is inputted by the user and one is the name of a thread. I inputted the name which should be the same as the thread. To verify this I have the program output

System.out.println("DS:" + DeamonMain.threadNameFinal + "CN:" +getName());

Which prints

DS:Thread-66CN:Thread-66

Now these appear to be the same string. However, when I have it test the validity of this using

boolean factChecker = DeamonMain.threadNameFinal == getName();
System.out.println(factChecker);

it prints false...

Why is this? Does this have to do with getName()? How are the string different and why so?

Most-asked question here? – Reinstate Monica -- notmaynard Jul 31 '13 at 16:10 — Reinstate Monica -- notmaynard, Jul 31 '13 at 16:10

score 2 · Accepted Answer · edited May 23 '17 at 12:05

2

You need to use String.equals to compare String equality, not the == sign.

As in:

boolean factChecker = DeamonMain.threadNameFinal.equals(getName());

The == operator checks for reference equality, while the equals method checks for the equality of your String values.

See also here for an older thread on the matter.

edited May 23 '17 at 12:05

Community

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answered Jul 31 '13 at 16:09

Mena

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score 1 · Answer 2 · answered Jul 31 '13 at 16:10

1

Again, and again...

Strings in Java are compared with equals(), not with ==.

Change your comparison to:

boolean factChecker = DeamonMain.threadNameFinal.equals(getName());

answered Jul 31 '13 at 16:10

Konstantin Yovkov

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score 0 · Answer 3 · answered Jul 31 '13 at 16:10

You should use the .equals() method to compare strings, rather than ==

boolean factChecker = DeamonMain.threadNameFinal.equals(getName());

The reason is that the .equals() tests for value equality (the strings have the same characters), while the == tests for reference equality.

score 0 · Answer 4 · answered Jul 31 '13 at 16:10

0

You need to use equals() method instead of ==

Like this:

DeamonMain.threadNameFinal.equals(getName())

answered Jul 31 '13 at 16:10

nkukhar

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Prabhaker A · Answer 5 · 2013-07-31T16:17:57.653

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Use equals() for String comparision instead of == operator

  boolean factChecker = DeamonMain.threadNameFinal.equals(getName());
  System.out.println(factChecker);

equals() method is used for content comparison where as == is reference comparison.

edited Jul 31 '13 at 16:17

answered Jul 31 '13 at 16:10

Prabhaker A

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Two string's which (I think) are identical do not return true when checking if the same

5 Answers5