Since
the Member class
implements the Comparable interface, it is possible to sort the list by using the sorted method.
What method must a class contain to implement the comparable interface?
For any class to support natural ordering, it should implement the Comparable interface and override it's
compareTo() method
. It must return a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object. Note that method must throw an exception if y.
Can we implement comparable interface?
We can implement the Comparable interface
with the Movie class
, and we override the method compareTo() of Comparable interface.
What does implements comparable mean?
Implementing a comparable interface means
that A can be compared with other instances of A
. Many operations in java that involve sorting use the methods defined in the Comparable interface to determine if instances of A are greater then less or equal to other instances.
Why do we implement comparable interface?
Comparable is
used to compare instances of your class
. We can compare instances from many ways that is why we need to implement a method compareTo in order to know how (attributes) we want to compare instances.
What is the comparable interface?
The Comparable interface defines
the `compareTo` method used to compare objects
. If a class implements the Comparable interface, objects created from that class can be sorted using Java's sorting algorithms. … The Comparable interface takes as its type parameter the class that is the subject of the comparison.
Is comparable a functional interface?
Literally Comparable is
a functional interface
as it declares one and only one abstract method.
When a class implements an interface it must?
A class that implements an interface must
implement all the methods declared in the interface
. The methods must have the exact same signature (name + parameters) as declared in the interface. The class does not need to implement (declare) the variables of an interface. Only the methods.
Which is faster and uses less memory?
Sqldatareader
is fast as compare to Dataset. Because it stored data in forward only and also stores only one record at a time. And dataset stores all records at the same time. This is the reason, SqlDataReader is faster than Dataset.
How do you implement the compareTo method?
The compareTo method compares the current object with the object sent as a parameter. When implementing it, we need to make sure that the method
returns
: A positive integer, if the current object is greater than the parameter object. A negative integer, if the current object is less than the parameter object.
What is comparable and comparator interface?
Comparable and comparator both are
an interface that can be used to sort the elements of the collection
. … Comparator interface sort collection using two objects provided to it, whereas comparable interface compares” this” refers to the one objects provided to it.
How do you sort an ArrayList?
To sort the ArrayList, you need to simply
call the Collections
. sort() method passing the ArrayList object populated with country names. This method will sort the elements (country names) of the ArrayList using natural ordering (alphabetically in ascending order).
Do you need to implement comparable to use compareTo?
compareTo() method. For any class to support natural ordering, it should implement the
Comparable interface
and override it's compareTo() method. It must return a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.
What does the hashCode () method?
| Method Return Value | hashCode(int value) This method returns the hashcode for the integer“value” passed through the function. |
|---|
Why is String immutable in Java?
The String is immutable in Java because
of the security, synchronization and concurrency, caching, and class loading
. The reason of making string final is to destroy the immutability and to not allow others to extend it. The String objects are cached in the String pool, and it makes the String immutable.
How do you use comparable to sort?
In Java, we can implement whatever sorting algorithm we want with any type. Using the Comparable interface and compareTo() method, we can sort using alphabetical order, String length, reverse alphabetical order, or numbers. The Comparator interface allows us to do the same but in a more flexible way.
