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Java Basics - Polymorphism

Java Basics - Polymorphism What is runtime polymorphism and compile time polymorphism. Method overloading in java is compile time polymorphis. Method overriding in java is runtime polymorphishm. What is method overloading in java. Method overloading - 2 or more methods having same method name but different parameters type list (method signature - name and parameter list) in certain class, then the 2 or more methods are said to be overloaded. Here the return type of the methods and the declared thrown exceptions in the methods is not considered for method overloading (i.e return types of the 2 methods can be different) Eg : public class A { public A method1(int a) throws ArithmeticException{ System.out.pri...

Java environment setup

Java environment setup What is java.library.path java.library.path is the path that Java uses to find native libraries (such as xyz.dll). We should set it to the directory that contains the DLL files. There are two ways to set java.library.path : 1. We specify this with the -D option on the command line, for example: java -Djava.library.path=C:\Java\abcd\libs com.mypckge.MyProgram The use of -D option is used to set system property values. 2. For Windows we can set this path( C:\Java\abcd\libs ) in the PATH environment variable. Once set in the environmental variable we will have to restart the system for the changes to take place effectively. Why do we need to set java.library.path There are certain cases where an api can refer to native libraries written in other languages. To provide those libraries in the api, we set them in the java.library.path . The error message can be one of these forms. can't load lbmj: jav...

Java Sorting - Comparable and Comparator

Java sorting Comparable and Comparator 1. Comparable in java is part of java.lang package, where as Comparator is part of java.util package 2. Comparable has compareTo(Object) method for sorting, where as Comparator has compare(Object, Object) method for sorting. 3. Using comparable we can sort only on a single entity of a class either age, sal or name at a time. Using comparator we can create multiple sorting classes on a single entity of a class, which we can pass as an object to the compare(object, object) method. Note : We need to implement the Comparable or Comparator interface only when we need to sort the data on custom classes. Eg : public class Employee implements Comparable{ int age; String name; Employee (int age, String name){ this.age=age; ...

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