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Possible Duplicate:
Comparing StringBuffer content with equals
StringBuffer s1= new StringBuffer("Test");
StringBuffer s2 = new StringBuffer("Test");
if(s1.equals(s2)) {
System.out.println("True");
} else {
System.out.println("False");
}
Why does that code print "False"?
507
The equals() method of the StringBuffer class But, unlike the Sting class the StringBuffer does not override the equals() method. Its functionality is same as in the Object class. Therefore, to get true you need to compare references pointing to the same value using the equal method.
StringBuffer's equals method returns true only when a StringBuffer object is compared with itself. It returns false when compared with any other StringBuffer, even if the two contain the same characters. Still if you want to check if the content is equal in these two StringBuffer Objects, you can use this: sb1.
When an object of String is passed, the strings are compared. But when object of StringBuffer is passed references are compared because StringBuffer does not override equals method of Object class.
A string buffer is like a String , but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls. String buffers are safe for use by multiple threads.
StringBuffer does not override the Object.equals method, so it is not performing a string comparison. Instead it is performing a direct object comparison. Your conditional may as well be if(s1==s2). If you want to compare the strings you'll need to turn the buffers into strings first.
See http://java.sun.com/j2se/1.5.0/docs/api/java/lang/StringBuffer.html
Edit: I'm assuming we're in a java world.
p.s. If you're in a single-threaded environment, or your buffers are isolated to a single thread, you should really be using a StringBuilder instead of a StringBuffer.
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