Built-in Exceptions in Java with examples
Types of Exceptions in Java Built-in exceptions are the exceptions which are available in Java libraries. These exceptions are suitable to explain certain error situations. Below is the list of important built-in exceptions in Java.
Examples of Built-in Exception:
1. Arithmetic exception : It is thrown when an exceptional condition has occurred in an arithmetic operation.
Java
class ArrayIndexOutOfBound_Demo {
public static void main(String args[])
{
try {
int a[] = new int [ 5 ];
a[ 6 ] = 9 ;
}
catch (ArrayIndexOutOfBoundsException e) {
System.out.println("Array Index is Out Of Bounds");
}
}
}
|
v>
Output:
Can't divide a number by 0
2. ArrayIndexOutOfBounds Exception : It is thrown to indicate that an array has been accessed with an illegal index. The index is either negative or greater than or equal to the size of the array.
Java
// Java program to demonstrate
// FileNotFoundException
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
class File_notFound_Demo {
public static void main(String args[])
{
try {
// Following file does not exist
File file = new File("E:// file.txt");
FileReader fr = new FileReader(file);
}
catch (FileNotFoundException e) {
System.out.println("File does not exist");
}
}
}
Output:
Array Index is Out Of Bounds
3. ClassNotFoundException : This Exception is raised when we try to access a class whose definition is not found.
Java
class Bishal {
} class Geeks {
} class MyClass {
public static void main(String[] args)
{
Object o = class .forName(args[ 0 ]).newInstance();
System.out.println("Class created for " + o.getClass().getName());
}
}
|
Output:
ClassNotFoundException
4. FileNotFoundException : This Exception is raised when a file is not accessible or does not open.
Java
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
class File_notFound_Demo {
public static void main(String args[])
{
try {
File file = new File("E:
FileReader fr = new FileReader(file);
}
catch (FileNotFoundException e) {
System.out.println("File does not exist");
}
}
}
|
Output:
File does not exist
5. IOException : It is thrown when an input-output operation failed or interrupted
JAVA
<div id= "highlighter_103206" class = "syntaxhighlighter nogutter " ><table border= "0" cellpadding= "0" cellspacing= "0" ><tbody><tr><td class = "code" ><div class = "container" ><div class = "line number1 index0 alt2" ><code class = "comments" >
|
Output:
error: unreported exception IOException; must be caught or declared to be thrown
6. InterruptedException : It is thrown when a thread is waiting, sleeping, or doing some processing, and it is interrupted.
JAVA
<div id= "highlighter_216585" class = "syntaxhighlighter nogutter " ><table border= "0" cellpadding= "0" cellspacing= "0" ><tbody><tr><td class = "code" ><div class = "container" ><div class = "line number1 index0 alt2" ><code class = "comments" >
|
Output:
error: unreported exception InterruptedException; must be caught or declared to be thrown
7. NoSuchMethodException : t is thrown when accessing a method which is not found.
JAVA
<div id= "highlighter_37259" class = "syntaxhighlighter nogutter " ><table border= "0" cellpadding= "0" cellspacing= "0" ><tbody><tr><td class = "code" ><div class = "container" ><div class = "line number1 index0 alt2" ><code class = "comments" >
|
Output:
error: exception NoSuchMethodException is never thrown
in body of corresponding try statement
8. NullPointerException : This exception is raised when referring to the members of a null object. Null represents nothing
JAVA
class StringIndexOutOfBound_Demo {
public static void main(String args[])
{
try {
String a = "This is like chipping ";
char c = a.charAt( 24 );
System.out.println(c);
}
catch (StringIndexOutOfBoundsException e) {
System.out.println("StringIndexOutOfBoundsException");
}
}
}
|
Output:
NullPointerException..
9. NumberFormatException : This exception is raised when a method could not convert a string into a numeric format.
JAVA
<div id= "highlighter_612687" class = "syntaxhighlighter nogutter " ><table border= "0" cellpadding= "0" cellspacing= "0" ><tbody><tr><td class = "code" ><div class = "container" ><div class = "line number1 index0 alt2" ><code class = "comments" >
|
Output:
Number format exception
10. StringIndexOutOfBoundsException : It is thrown by String class methods to indicate that an index is either negative than the size of the string.
JAVA
class Test {
public static void main(String[] args)
{
m1();
}
public static void m1()
{
m2();
}
public static void m2()
{
m1();
}
}
|
Output:
StringIndexOutOfBoundsException
Some other important Exceptions
1. ClassCastException
JAVA
class Test
{
public static void main(String[] args)
{
System.out.println("HELLO GEEKS");
}
}
|
Output:
Exception in thread "main" java.lang.ClassCastException:
java.lang.Object cannot be cast to java.lang.String
2. StackOverflowError
JAVA
class Test {
static int x = 10 / 0 ;
public static void main(String[] args)
{
}
}
|
Output:
Exception in thread "main" java.lang.StackOverflowError
3. NoClassDefFoundError
JAVA
class Test {
static
{
String s = null ;
System.out.println(s.length());
}
public static void main(String[] args)
{
}
}
|
Output:
Note: If the corresponding Test.class file is not found
during compilation then we will get Run-time Exception
saying Exception in thread "main" java.lang.NoClassDefFoundError
4. ExceptionInInitializerError
Code 1:
JAVA
class Test {
public static void main(String[] args)
{
Thread t = new Thread();
Thread t1 = new Thread();
t.setPriority( 7 );
t1.setPriority( 17 );
}
}
|
Output:
Exception in thread "main" java.lang.ExceptionInInitializerError
Caused by: java.lang.ArithmeticException: / by zero
Code 2 :
Output:
Exception in thread "main" java.lang.ExceptionInInitializerError
Caused by: java.lang.NullPointerException
Explanation : The above exception occurs whenever while executing static variable assignment and static block if any Exception occurs.
5. IllegalArgumentException
JAVA
class Test {
public static void main(String[] args)
{
Thread t = new Thread();
Thread t1 = new Thread();
t.setPriority( 7 );
t1.setPriority( 17 );
}
}
|
Output:
Exception in thread "main" java.lang.IllegalArgumentException
Explanation:The Exception occurs explicitly either by the programmer or by API developer to indicate that a method has been invoked with Illegal Argument.
6. IllegalThreadStateException
JAVA
public void setAge( int age) {
if (age < 0 || age > 120 ) {
throw new IllegalArgumentException( "Invalid age" );
}
this .age = age;
}
|
Output:
Exception in thread "main" java.lang.IllegalThreadStateException
Explanation : The above exception rises explicitly either by programmer or by API developer to indicate that a method has been invoked at wrong time.
7. AssertionError
Output:
Exception in thread "main" java.lang.AssertionError
Explanation : The above exception rises explicitly by the programmer or by API developer to indicate that assert statement fails.
IllegalArgumentException: This exception is thrown when an illegal argument is passed to a method. For example:
Java
public void setAge( int age) {
if (age < 0 || age > 120 ) {
throw new IllegalArgumentException( "Invalid age" );
}
this .age = age;
}
|
FileNotFoundException: This exception is thrown when a file cannot be found. For example:
Java
try {
FileReader reader = new FileReader( "file.txt" );
} catch (FileNotFoundException e) {
System.out.println( "File not found" );
}
|
Last Updated :
12 Jun, 2023
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