Is it possible to do something like this in Java for Android (this is a pseudo code) IF (some_string.equals("john" OR "mary" OR "peter" OR "etc."){ THEN do something } ? At the moment this is done via multiple String.equals() condition with || among them. on the oracle java documentation, equals () from list says two lists are defined to be equal if they contain the same elements. But from object class equals () return true only if their hash code is equal. It means equals () from list overrides equals method from object class. And it's same for equals () from string. One way to avoid the NPE when using .equals(Object) is to invoke the equals method against an enum constant or a known non-null enum and then pass the potential enum of questionable character In Java, the equals() and hashCode() methods are used to define object equality and to enable the effective use of objects in hash-based data structures such as HashMap, HashSet, etc. Question 2 : If the answer is because they both have same hash code,only then equals will be called, then why its not called for below code. sset.add (obj1); sset.add (obj4); sset.add (obj2); sset.add (obj4); output is : in hash code value is 98 in hash code value is 97 in hash code value is 99 in hash code value is 97. If you are overriding equals in order to be able to use some containers, you are very likely to accidentally stick it into a container which uses hashcode. It doesn't take many keystrokes to change container type in Java, and you should be using interface types instead of actual container class names anyway, so you shouldn't even care which MIioZW. When you add autoboxing to the mix, things are slightly different. A primitive is always autoboxed to its wrapper type. Here, 0, which is an int literal, is autoboxed to a java.lang.Integer wrapper instance. Since java.lang.Long and java.lang.Integer are different classes, equals between them must return false. 13. When I read a Java book, author has said that, when designing a class, it's typically unsafe to use equals () with inheritance. For example: public final class Date { public boolean equals (Object o) { // some code here } } In the class above, we should put final, so other class cannot inherit from this. How to use equals() and equalsIgnoreCase() in Java - The equals() methodThis method compares this string to the specified object. The result is true if and only if the argument is not null and is a String object that represents the same sequence of characters as this object.Exampleimport java.lang.*; public class StringDemo { public static void m When we use == , the Reference of object is compared not the actual objects. We need to override equals method to compare Java Objects. Some additional information C++ has operator over loading & Java does not provide operator over loading. Also other possibilities in java are implement Compare Interface.which defines a compareTo method. Compare Enum Using the equals() Method in Java. Java equals() method compares two values and returns a boolean value, either true or false. We can use this method to compare enum values. Here, we used the Color enum to compare its values. The first value returns false, but it returns true for the second. See the example below.

how to use equals method in java