import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class ExceptionDemo
{
public static void main(String[] args)
{
String fileName = null;
Scanner scanner = new Scanner(System.in);
System.out.print("Enter the fileName:");
String value = scanner.next();
if (value.length() > 5)
{
fileName = value;
}
scanner.close();
FileReader fileReader = null;
// Handle them using try-catch blocks.
try
{
/*
* This constructor FileReader(File filename)
* throws FileNotFoundException which is a
* checked exception
*/
fileReader = new FileReader(fileName);
int i;
/*
* Method read() of FileReader class also throws
* a checked exception: IOException
*/
while ((i = fileReader.read()) != -1)
{
System.out.print((char) i);
}
}
catch (FileNotFoundException fileNotFoundException)
{
System.out.println("The specified file is not "
+ "present at the given path.");
}
catch (IOException ioException)
{
System.out.println("I/O error occurred: " + ioException);
}
finally
{
try
{
System.out.println(" \nInside finally block");
/*
* The method close() closes the
* fileReader,It throws IOException
*/
if (fileReader != null)
{
fileReader.close();
}
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
}
Enter the fileName:hello.txt
The specified file is not present at the given path.
Inside finally block
----------------------------------------------
Enter the fileName:a.txt
Inside finally block
Exception in thread "main" java.lang.NullPointerException
at java.io.FileInputStream.<init>(FileInputStream.java:130)
at java.io.FileInputStream.<init>(FileInputStream.java:93)
at java.io.FileReader.<init>(FileReader.java:58)
at ExceptionDemo.main(ExceptionDemo.java:34)
import java.util.HashMap;
import java.util.LinkedHashMap;
public class OutOfMemoryDemo
{
public static void main(String[] args)
{
String str = "Hello";
HashMap<String,String> map = new LinkedHashMap<String,String>();
while(true)
{
str = str+"Welcome to india";
map.put(str, str);
}
}
}
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