Tag: equals

How to compare strings in Java?

Test strings equality

==  tests object references, .equals()  tests the string values.

Sometimes it looks as if == compares values, because Java does some behind-the-scenes stuff to make sure identical in-line strings are actually the same object.

For example:

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String fooString1 = new String("foo");
String fooString2 = new String("foo");
 
// Evaluates to false
fooString1 == fooString2;
 
// Evaluates to true
fooString1.equals(fooString2);
 
// Evaluates to true, because Java uses the same object
"bar" == "bar";

Correct null handling

== handles null strings fine, but calling .equals() from a null string will cause an exception:

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String nullString1 = null;
String nullString2 = null;
 
// Evaluates to true
nullString1 == nullString2;
 
// Throws an Exception
nullString1.equals(nullString2);