Why will you use Comparator and Comparable interfaces? | Eklavya Online

Why will you use Comparator and Comparable interfaces?

java.util.Comparator
java.util.Comparator compares some other class’s instances.

java.lang.Comparable
java.lang.Comparable compares another object with itself.

Differentiate between final, finally and finalize.

The keyword is final. It is used for declaring a constant It prevents a class from producing subclasses.

finally is a code.It always executes when the try block is finished, Unless System.exit() has been called.finalize() is a method, Before discarding by the garbage collector it is invoked.

Differentiate JAR and WAR files

JAR files:

  • JAR files is the acronym stands for Java ARchive fles.
  • JAR files allow aggregating many files into one,
  • JAR is usually used to hold Java classes in a library.

WAR files:

  • WAR files is the acronym stands for Web ARchive fles.
  • WAR stores XML, java classes, and JavaServer pages
  • WAR is mainly used for Web Application purposes.

In a Java , how can you send program messages on the system console, but error messages, to a file?

The class System has a variable out that denotes the standard output.

The standard error device represents the variable err .

Naturally, they both point at the system console.

 

In this way, the standard output can be sent to the file:

Stream x = new Stream(new FileOutputStream(“error.txt”));

System.setErr(x);

System.Out(x);