Difference between Static vs non Static method in Java

Difference between Static vs non Static method in Java

One of the key difference between a static and a non-static method is that static method belongs to a class while non-static method belongs to the instance. This means you can call a static method without creating any instance of the class by just using the name of the class e.g. Math.random() for creating random numbers in Java. Often utility methods which don't use the member variables of the class are declared static. On the other hand, you need an instance of the class to call a non-static method in Java. You cannot call it without creating an object because they are dependent upon the member variables which has different values for different instances.  One more important difference between the static and non-static method is that you cannot use a non-static member variable inside a static method, you cannot even call a non-static method from the static method, but the opposite is true e.g. you can call a static function from a non-static method in Java.

Difference between static and nonstatic member variables in Java

Difference between static and nonstatic member variables in Java

The concept of static remains same, that doesn't change with method or member variables but there are still some subtle details, which every Java programmer should know and understand. As with static methods, a static member variable belongs to a class and a non-static member variable belongs to an instance. This means, the value of a static variable will be same for all instances, but the value of a non-static variable will be different for different objects. That is also referred as the state of objects. The value of nonstatic member variable actually defines the state of objects.

Difference between BufferedReader and Scanner class in Java - Example

Difference between BufferedReader and Scanner class in Java - Example

Even though both BufferedReader and Scanner can read a file or user input from command prompt in Java, there some significant differences between them. One of the main difference between BufferedReader and Scanner class is that former is meant to just read String while later is meant to both read and parse text data into Java primitive type e.g. int, short, float, double, and long. In other words, BufferedRedaer can only read String but Scanner can read both String and other data types like int, float, long, double, float etc. This functional difference drives several other differences on their usage. Another difference is Scanner is newer than BufferedReader, only introduced in Java 5, while BufferedReader is present in Java from JDK 1.1 version. This means, you have access to BufferedReader in almost all JDK version mainly Java 1.4 but Scanner is only available after Java 5.  This is also a popular core Java questions from interviews. Since many developer lack Java IO skill, questions like this test their knowledge about API and how to do some practical task.

Difference between final vs finally and finalize in Java

Difference between final vs finally and finalize in Java

The final, finally, and finalize are one of the three confusing keywords, modifiers and methods in Java. They sounds similar but they are for different purpose. For example, final keyword is a modifier in Java. When you use final keyword with a class it becomes a final class and no one can extend this e.g. String is final in Java. When you use the final modifier with method than it cannot be overridden in subclass, and when you use the final keyword with variable, it become a constant i.e. its value cannot be changed once assigned. On the other hand, finally is a keyword related to exception handling in Java. It's often used with try block and it's part of try, catch and finally trio. A finally block can be used with or without catch block in Java and its guaranteed to be always executed, irrespective of what happens inside try block. This is the reason finally block is used to do cleanup and free resources.

Difference between HashMap vs IdentityHashMap in Java

Difference between HashMap vs IdentityHashMap in Java

The IdentityHashMap is one of the lesser known Map implementation from JDK. Unlike general purposes Map implementations like HashMap and LinkedHashMap, it is very special and it's internal working is quite different than HashMap. The main difference between IdentityHashMap and HashMap in Java is that former uses equality operator (==) instead of equals()method to compare keys. Which means you need the same key object to retrieve the value from IdentityHashMap, you cannot retrieve values by using another key which is logically equal to previous key. Another important difference between HashMap and IdentityHashMap is that IdentityHashMap doesn't use hashCode() method instead it uses System.identityHashCode() method. This is a significant difference because now you can use mutable objects as key in Map whose hash code are likely to change when the mapping is stored inside IdentityHashMap.