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copied!<p><code>==</code> for reference types compares the references; <code>==</code> for primitive types compares values. In case of your first example, the two object references turn out to be the same due to a concept known as string pool. Hence two <code>true</code> in the given case. Another code snippet you might want to try out:</p> <pre><code>String s1 = "abc"; String s2 = new String("abc"); System.out.println(s1 == s2); System.out.println(s1.equals(s2)); </code></pre> <p>As you must have already tried out; it prints out <code>false</code> and then <code>true</code>. The reason for this is that using the <code>new</code> keyword results in the creation of a completely new string even though a string object with the exact same contents already exists in the string pool. In this case, <code>s1</code> now points to an interned string with the contents "abc" (or to a string in the string pool) whereas <code>s2</code> now points to a completely new string object (again with the content "abc"). Hence the <code>false</code> in the first print statement.</p> <p>In the second print statement, what we are doing is comparing the contents of the String object rather than its reference, which as it should prints <code>true</code>.</p> <p>This is one of the most common mistakes made by beginners of the Java language; they use <code>==</code> for logical comparison when it actually results in a reference comparison. Read the link posted in one of the answers here for more details about string pooling. On a related note, String class "overrides" the <code>equals</code> method of the <code>Object</code> class to provide a logical comparison. Unless the class you write doesn't provide a logical implementation of the <code>equals</code> method, it doesn't matter whether you call <code>equals</code> or use the <code>==</code> operator; the result would be the same i.e. reference comparison.</p> <p>For a more in-depth view on equality, <a href="http://www.ibm.com/developerworks/java/library/j-jtp05273.html" rel="noreferrer">read Brian's article; an excellent read</a>.</p>

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