Introduction This tutorial shows how to compare date without time in Java between two dates. Situation may arise when you need to compare two dates in your Java applications and if you need to compare only date part without time part for accurate results then you need to first remove the time part from the…

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Compare date without time in Java

In this example I am going to show you an example on using Comparator in HashMap will show you how to use Comparator to sort values in HashMap. I will use custom object as a key in the HashMap. The object which is used as an object as a key in HashMap must override hashCode()…

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Using Java Comparator in HashMap to Sort Elements

In this post, I will show you how to remove duplicate objects from a List using Java’s Comparator interface implementation based on multiple fields in a POJO. You can also check the duplicate objects in a list by overriding hashCode() and equals() methods in the POJO class. In other words, you are going to get…

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Remove Duplicate Objects from a List using Java

In this post, I will show you how to find duplicate objects in a List using Java’s Comparator interface implementation based on multiple fields in a POJO. Prerequisites The following configurations are required in order to run the application Eclipse JDK 1.8 Have maven installed and configured Junit, Mockito, PowerMockito dependency in pom.xml Now we…

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Find Duplicate Objects in a List using Java

We will see what is comparator interface and how to use comparator interface in Java programming language. For more information please go through http://docs.oracle.com/javase/7/docs/api/java/util/Comparator.html A comparison function, which imposes a total ordering on some collection of objects. Comparator can be passed to a sort method (such as Collections.sort() or Arrays.sort()) to allow precise control over…

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Comparator interface in Java

For more information please go through http://docs.oracle.com/javase/7/docs/api/java/lang/Comparable.html This interface imposes a natural ordering on objects of each class that implements it and the class’s compareTo method is referred to as its natural comparison method. Lists or arrays of objects that implement this interface can be sorted automatically by Collections.sort or Arrays.sort respectively. Objects that implement…

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Comparable interface in Java