When to throw IllegalStateException and IllegalArgumentException? In Java?

IllegalStateException:

An exception will be generated and an IlleagalStateException will be created when you call the method at an illegal or inappropriate time.

For example,remove()is called on the ArrayList class methodnext()Delete the last element after the method or before.

• After deleting the element at the current position, you need to move to the next element to delete it, that is, each time you call thisnext()When calling thisremove()method once.

• Since the initial position of the list (pointer) will be before the first element, this method cannot be called without calling the next method.

If calling thisremove()method, otherwise it will throw java.lang.IllegalStateException.

Example

In the following example, we try to useremove()The method removes an element from the ArrayList and then moves to the first element

import java.util.ArrayList;
import java.util.ListIterator;
public class NextElementExample{
　　　public　static　void　main(String　args[])　{
　　　　　　//Instantiate an ArrayList object
　　　　　　ArrayList<String> list = new ArrayList<String>();
　　　　　　//Fill the ArrayList-
　　　　　　list.add("apples");
　　　　　　list.add("mangoes");
　　　　　　//Get the Iterator object of ArrayList
　　　　　　ListIterator<String> it = list.listIterator();
　　　　　　//Remove an element without moving to the first position
　　　　　　it.remove();
　　　}
}

Runtime Exception

Exception in thread "main" java.lang.IllegalStateException
　　　at java.util.ArrayList$Itr.remove(Unknown Source)
　　　at MyPackage.NextElementExample.main(NextElementExample.java:17)

IllegalArgumentException-IllegalArgumentException will be thrown whenever inappropriate parameters are passed to a method or constructor.

Example

valueOf()The methods of the java.sql.Date class accept a String in JDBC escape format yyyy- [m] m- [d] d represents a date String and converts it to a java.sql.Date object. However, if the date String is passed in any other format, this method will throw an IllegalArgumentException.

import java.sql.Date;
import java.util.Scanner;
public　class　IllegalArgumentExample　{
　　　public　static　void　main(String　args[])　{
　　　　　　Scanner　sc　=　new　Scanner(System.in);
　　　　　　System.out.println("Enter　your　date　of　birth　in　JDBC　escape　format　(yyyy-mm-dd)　");
　　　　　　String　dateString　=　sc.next();
　　　　　　Date　date　=　Date.valueOf(dateString);
　　　　　　System.out.println("Given　date　converted　int　to　an　object:　"+date);
　　　}
}

Runtime Exception

Enter　your　date　of　birth　in　JDBC　escape　format　(yyyy-mm-dd)
26-07-1989
Exception　in　thread　"main"　java.lang.IllegalArgumentException
　　　at　java.sql.Date.valueOf(Unknown　Source)
　　　at　july_ipoindi.NextElementExample.main(NextElementExample.java:11)