// Strings.java  Demo of String functionality

public class Strings
{	public static void main (String args[]) throws Exception
	{		// initialize via assignment vs. constructor
		String s1 = "Hello"; // assignment
		String s2 = new String( "World" ); // constructor
		String s3 = s1 + " " + s2; // s3 is now --> "Hello World;
    
		// .length method built into every String
		System.out.println("The length of s3 is: " + s3.length() ); // prints out 11
		
		// .charAt method built into every String
		System.out.println("\nThe third letter in s3 is: " + s3.charAt(2) ); // 1st at [0] 2nd at [1] 3rd at [2] etc.
		
		// combine charAt and length to print the string backwards
		System.out.print( "\n" + s3 + " backwards is: ");
		for ( int i=s3.length()-1 ; i>=0 ; i--)
			System.out.print( s3.charAt(i) ); 
		System.out.println();
		
		// .indexOf method built into every String. Searches for letter. If not found returns -1
		System.out.println("\nThe letter 'W' is at index: " + s3.indexOf('W') ); // prints 6
		
		// boolean  .startsWith method built into every String. Try out .endsWith() yourself
		if ( s3.startsWith("Hello") )
			System.out.println("\nThe literal text \"Hello\" is a prefix of s3");
		
		// boolean  .equals() method  built into every String. 
		if ( s1.equals( s2 ) )
			System.out.println("\n" +  s1 + " is char by char identical with " + s2 );
		else
			System.out.println( "\n" + s1 + " is NOT char by char identical with " + s2 );
		
		// toUpperCase() method built into every String.  Try out .toLowerCase() yourself
		System.out.println("\n" +  s3 + " converted to all upperCase is " + s3.toUpperCase() );
		System.out.println( "But calling .toUpperCase() does not modify s3.\nIt is still " + s3 );
		
		// .substring() method built into every String. 
		int fromInd=0,toInd=4;
		System.out.println( "\nThe first 4 chars of s3 are: " + s3.substring(fromInd,toInd) );  // only get 0..3 
		System.out.println( ".substring() does not modify s3." );
	} // END MAIN
} // END STRINGS CLASS