Java Questionnaire III

class StringDemo
{	
	public void ConcatenateString()
	{
		String str = "this";
		str += " is";
		str += " the";
		str += " demonstration";
		System.out.println(str);
	}

	public void ConcatenateStringBuffer()
	{
		StringBuffer str = new StringBuffer("this");
		str.append(" is");
		str.append(" the");
		str.append(" demonstration");
		System.out.println(str);
	}
}

class MainClass
{
	public static void main(String args[])
	{
          StringDemo s = new StringDemo();
          s.ConcatenateString();
          s.ConcatenateStringBuffer(); // This method is quicker than the ConcatenateString() method
	}
}

interface I
{
	void Display();
}

class MainClass
{
	public static void main(String args[])
	{		
		I obj = new I();		
	}
}

class MultipleExceptionClass
{
	void CallMethod()
	{
		try
		{
			//	This condition will invoke ArithmeticException exception
			//int x = 0;
			//int y = 5/x;
			
			//	This condition will invoke ArrayIndexOutOfBoundsException exception
			//int a[] = new int[2];
			//int x = a[3];
		}
		catch(ArithmeticException e1)
		{
			System.out.println("Divided by zero exception");
		}
		catch(ArrayIndexOutOfBoundsException e2)
		{
			System.out.println("Null exception");
		}
	}
}

class MainClass
{
	public static void main(String args[])
	{		
		MultipleExceptionClass c = new MultipleExceptionClass();
		c.CallMethod();

	}	
}

public abstract class MyAbstractClass {   
   void Display()
   {
		// Method definition
   }
}

class MainClass
{
	public static void main(String args[])
	{		
		MyAbstractClass c = new MyAbstractClass();
	}	
}

class MainClass
{
   public static void main(String aa[])
   {
	double d = 22.55;
	byte b = (byte)d;
	System.out.println(b);	  
   }
}

class MainClass
{
   public static void main(String aa[])
   {
	Double dObj = new Double("22.55");			
	byte b = dObj.byteValue();
	System.out.println(b);	  
   }
}

class ThrowDemo
{
	void CallMethod()
	{
		String str = null;

		if(str == null)
		{
			throw new NullPointerException();
		}		
	}
}
class MainClass
{
	public static void main(String aa[])
	{
		try
		{
			ThrowDemo e = new ThrowDemo();
			e.CallMethod();
		}
		catch(NullPointerException ex)
		{
			System.out.println("NullPointerException caught");
		}	  
  	 }
}

class InstanceOfGetClassDemo
{
	public void CallMethod()
	{
		String s = "";
		
		if(s instanceof String)
		{
			System.out.println("s is of type String");		
		}
		
		
		System.out.println(s.getClass().getName());
	}
}
public class MyClass {

	public static void main(String args[])
	{
		InstanceOfGetClassDemo c = new InstanceOfGetClassDemo();
		c.CallMethod();
	}
}

Query/Feedback