// Document.java
/*Define a class named Document that contains an instance 
 * variable of type String named text that stores any 
 * textual content for the document. Create a method 
 * named toString that returns the text field and 
 * also include a method to set this value.
 * */
public class Document 
{
	private String text;

	public Document(String textDoc)
	{
		setText(textDoc);
	}
	public void setText(String newTextDoc) 
	{
		text = newTextDoc;
	}
	public String toString()
	{
		return text;
	}
} 

//Email.java
/*Define a class for Email that is derived from Document 
 * and includes instance variables for the sender, recipient,
 * and title of an email message. Implement appropriate 
 * accessor and mutator methods. The body of the email
 *  message should be stored in the inherited variable 
 *  textDoc. Redefine the toString method to concatenate 
 *  all textDoc fields. 
 * */
public class Email extends Document 
{
	private String sender;
	private String recipient;
	private String title;

	public Email(String textDoc, String senderMsg, String recipientMsg, String titleMsg) 
	{

		super(textDoc);
		sender = senderMsg;
		recipient = recipientMsg;
		title = titleMsg;
	}

	public String getSender()
	{
		return sender;
	}

	public String getRecipient() 
	{
		return recipient;
	}

	public String getTitle() 
	{
		return title;
	}

	public String gettext()
	{
		return super.toString();
	}

	public void setSender(String newSenderMsg)
	{
		sender = newSenderMsg;
	}

	public void setRecipient(String newRecMsg)
	{
		recipient = newRecMsg;
	}

	public void setTitle(String newTitleMsg) 
	{
		title = newTitleMsg;
	}

	public String toString() 
	{
		return "From: " + sender + "\nTo: " + recipient + "\n" + title + "\n\n" + super.toString();

	}
}

//main class, File.java
/*define a class for File that is derived from Document 
 * and includes a instance variable for the pathname . 
 * The textual contents of the file should be stored
 *  in the inherited variable text. Redefine the
 *  toString method to concatenate all text fields.
 *   Finally, create several sample objects 
 *   of type Email and File in your main method. 
 * */
public class File extends Document 
{

	private String pathname;

	public File(String textMsg, String pathDes) 
	{
		super(textMsg);
		pathname = pathDes;
	}

	public String getPathname()
	{
		return pathname;
	}

	public String getText() 
	{
		return super.toString();
	}

	public void setPathname(String newPath)
	{
		pathname = newPath;
	}

	public String toString() 
	{
		return pathname + ": " + super.toString();
	}

	public static boolean ContainsKeyword(Document docObject, String keyword)
	{
		if (docObject.toString().indexOf(keyword, 0) >= 0)
			return true;

		return false;
	}

	public static void main(String args[]) 
	{
		String sample1 = "The childrens playing cricket" + " were extremely noisy.";
		String sample2 = "The lion stared at the dog " + "across the street.";
		Document email1 = new Email(sample1, "Peter", "Martin", "Childrens");
		Document email2 = new Email(sample2, "Josh", "Lucky", "animals");

		Document file1 = new File(sample1, "childrens.txt");
		Document file2 = new File(sample2, "animals.txt");
		String testWord = "Cricket";
		if (ContainsKeyword(email1, testWord))
			System.out.println("Email 1 contains the word " + testWord);
		else
			System.out.println("Email 1 does not contain " + "the word " + testWord);
		if (ContainsKeyword(email2, testWord))
			System.out.println("Email 2 contains the word " + testWord);
		else
			System.out.println("Email 2 does not contain" + " the word " + testWord);
		if (ContainsKeyword(file1, testWord))
			System.out.println("File 1 contains the word " + testWord);
		else
			System.out.println("File 1 does not contain" + " the word " + testWord);
		if (ContainsKeyword(file2, testWord))
			System.out.println("File 2 contains the word " + testWord);
		else
			System.out.println("File 2 does not contain" + " the word " + testWord);
		System.out.println("---");
		System.out.println(email1.toString());
		System.out.println("---");
		System.out.println(email2.toString());
		System.out.println("---");
		System.out.println(file1.toString());
		System.out.println(file2.toString());

	}
}

OUTPUT:

Email 1 does not contain the word Cricket
Email 2 does not contain the word Cricket
File 1 does not contain the word Cricket
File 2 does not contain the word Cricket
---
From: Peter
To: Martin
Childrens

The childrens playing cricket were extremely noisy.
---
From: Josh
To: Lucky
animals

The lion stared at the dog across the street.
---
childrens.txt: The childrens playing cricket were extremely noisy.
animals.txt: The lion stared at the dog across the street.