Unhandled Exception Type FileNotFoundException

Hi there. I'm trying to do a file reader which is accessible via a menu system but i keep getting the error “unhandled exception type FileNotFoundException” at the

Code :

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 else inputCommandFile();

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Code :

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import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;
import javax.swing.JOptionPane;
import edu.cmu.ri.createlab.terk.robot.finch.Finch;
 
 
 
public class RobotController1  {
	private static Finch myf = null;
 
 
	public static void main(String[] args) {	
		myf = new Finch();
		String lastCommand = null;
		int count =1;
		for (String input = getInput(); !input.equals("End Program"); input = getInput()) 
		{  
			if (!input.equals(lastCommand)) 
			{
 
				if (input.equals("Forward")) moveForward();
				else if (input.equals("Back")) moveBack();
				else if (input.equals("Left Turn")) moveLeft();
				else if (input.equals("Right Turn")) moveRight();
				else if (input.equals("Nose Colour")) greenLED();
				else  if (input.equals("Three Point Turn")) threePointTurn(); //Three point turn
				else inputCommandFile();
 
				lastCommand = input;
				System.out.println(count);
 
			} 
			else 
			{
				JOptionPane.showMessageDialog(null, input + " cannot be chosen directly after " + lastCommand,"ERROR",0);
 
			}
 
 
		}
		while (count <8);
		System.out.println("Finch Disconnected...");
		myf.quit();
 
	} 
 
	private static String getInput() {
		Object[] possibilities = {"Forward","Back","Left Turn","Right Turn", "Nose Colour" ,"Three Point Turn","Input Command File","End Program"};
		String c = (String)JOptionPane.showInputDialog(null,"Robot Controller \n\nChoose a command:\n\n","Robot Controller",JOptionPane.PLAIN_MESSAGE, null,possibilities,"Forward");
		if (c == null || c.length() == 0) 
			c = "End Program";
		return c;
	}
 
private static String inputCommandFile(String s) throws FileNotFoundException	
	{	
 
		File file = new File("h:\\My Documents\\Inputfile.txt");							
 
		Scanner sc = new Scanner(new FileInputStream(file));		
 
		int numoflinesread=0;
		int Maxlines=7;//maximum amount of commands it can read is 7
 
	    String line = null;
		while(sc.hasNextLine())
		{ 
		line = sc.nextLine(); 
 
		if (line.indexOf("Nose") > -1) 
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Forward ") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Backward") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Left") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Right") > -1)
		{
		stringconversion(line); 
		}
 
		numoflinesread++;
		if (numoflinesread==Maxlines)
		{
		break;
		}
		return line;
		}
		return line;
 
 
	}

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Please help me, I've watched tutorials etc. but I'm at my wits end now. Thank you :)

Code :

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private static String inputCommandFile(String s) throws FileNotFoundException

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That method is defined to throw an exception. Any code that calls that method must be ready to handle the exception either with a try{}catch block or a further throws clause.

See the tutorial:
Lesson: Exceptions (The Java™ Tutorials > Essential Classes)

Quote:

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Originally Posted by Norm

Code :

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private static String inputCommandFile(String s) throws FileNotFoundException

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That method is defined to throw an exception. Any code that calls that method must be ready to handle the exception either with a try{}catch block or a further throws clause.

See the tutorial:
Lesson: Exceptions (The Java™ Tutorials > Essential Classes)

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do i add the catch onto the method?

Hi there. I'm trying to do a file reader which is accessible via a menu system but i keep getting the error “unhandled exception type FileNotFoundException” at the

Code :

---

 else inputCommandFile();

---

Code :

---

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;
import javax.swing.JOptionPane;
import edu.cmu.ri.createlab.terk.robot.finch.Finch;
 
 
 
public class RobotController1  {
	private static Finch myf = null;
 
 
	public static void main(String[] args) {	
		myf = new Finch();
		String lastCommand = null;
		int count =1;
		for (String input = getInput(); !input.equals("End Program"); input = getInput()) 
		{  
			if (!input.equals(lastCommand)) 
			{
 
				if (input.equals("Forward")) moveForward();
				else if (input.equals("Back")) moveBack();
				else if (input.equals("Left Turn")) moveLeft();
				else if (input.equals("Right Turn")) moveRight();
				else if (input.equals("Nose Colour")) greenLED();
				else  if (input.equals("Three Point Turn")) threePointTurn(); //Three point turn
				else inputCommandFile();
 
				lastCommand = input;
				System.out.println(count);
 
			} 
			else 
			{
				JOptionPane.showMessageDialog(null, input + " cannot be chosen directly after " + lastCommand,"ERROR",0);
 
			}
 
 
		}
		while (count <8);
		System.out.println("Finch Disconnected...");
		myf.quit();
 
	} 
 
	private static String getInput() {
		Object[] possibilities = {"Forward","Back","Left Turn","Right Turn", "Nose Colour" ,"Three Point Turn","Input Command File","End Program"};
		String c = (String)JOptionPane.showInputDialog(null,"Robot Controller \n\nChoose a command:\n\n","Robot Controller",JOptionPane.PLAIN_MESSAGE, null,possibilities,"Forward");
		if (c == null || c.length() == 0) 
			c = "End Program";
		return c;
	}
 
private static String inputCommandFile(String s) throws FileNotFoundException	
	{	
 
		File file = new File("h:\\My Documents\\Inputfile.txt");							
 
		Scanner sc = new Scanner(new FileInputStream(file));		
 
		int numoflinesread=0;
		int Maxlines=7;//maximum amount of commands it can read is 7
 
	    String line = null;
		while(sc.hasNextLine())
		{ 
		line = sc.nextLine(); 
 
		if (line.indexOf("Nose") > -1) 
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Forward ") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Backward") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Left") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Right") > -1)
		{
		stringconversion(line); 
		}
 
		numoflinesread++;
		if (numoflinesread==Maxlines)
		{
		break;
		}
		return line;
		}
		return line;
 
 
	}

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Quote:

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do i add the catch onto the method?

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Did you read the tutorial? What you just asked does not make sense.
catch goes with the try statement.
methods use the throws clause

Ok so I did it, it worked but then randomly stopped working even though I made no changes to the correct version

Code :

---

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Scanner;
import javax.swing.JOptionPane;
import edu.cmu.ri.createlab.terk.robot.finch.Finch;
 
 
 
public class RobotController1  {
	private static Finch myf = null;
 
 
	public static void main(String[] args) throws FileNotFoundException  {	
		myf = new Finch();
		String lastCommand = null;
		int count =1;
		for (String input = getInput(); !input.equals("End Program"); input = getInput()) 
		{  
			if (!input.equals(lastCommand) || input.equals("Left Turn")|| input.equals("Right Turn") || input.equals("Nose Colour") ) 
 
 
			{
 
				if (input.equals("Forward")) moveForward();
				else if (input.equals("Back")) moveBack();
				else if (input.equals("Left Turn")) moveLeft();
				else if (input.equals("Right Turn")) moveRight();
				else if (input.equals("Nose Colour")) greenLED();
				else  if (input.equals("Three Point Turn")) threePointTurn(); //Three point turn
				else  inputCommandFile(input); 
 
				lastCommand = input;
				System.out.println(count);
 
			} 
			else 
			{
				JOptionPane.showMessageDialog(null, input + " cannot be chosen directly after " + lastCommand,"ERROR",0);
 
			}
 
 
		}
		while (count <8);
		System.out.println("Finch Disconnected...");
		myf.quit();
 
	} 
 
 
 
private static String inputCommandFile(String s) throws FileNotFoundException	
	{	
 
		File file = new File("C:\\Users\\Omar\\Desktop\\Inputfile.txt");							
 
		Scanner sc = new Scanner(new FileInputStream(file));		
 
		int numoflinesread=0;
		int Maxlines=7;//maximum amount of commands it can read is 7
 
	    String line = null;
		while(sc.hasNextLine())
		{ 
		line = sc.nextLine(); 
 
		if (line.indexOf("Nose") > -1) 
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Forward ") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Backward") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Left") > -1)
		{
		stringconversion(line); 
		}
		else if (line.indexOf("Right") > -1)
		{
		stringconversion(line); 
		}
 
		numoflinesread++;
		if (numoflinesread==Maxlines)
		{
		break;
		}
		return line;
		}
		return line;
 
 
	}

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Quote:

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stopped working

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Can you explain what " stopped working" means?

What happens with the String returned by the inputCommandFile() method?

Quote:

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Originally Posted by Norm

Can you explain what " stopped working" means?

What happens with the String returned by the iputCommandFile() method?

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Basically, I have a Finch robot which I'm programming. The method reads commands to move the Finch from a file. Also the method prevents more than 7 commands being executed.

Are you talking about another part of the program, not the throws clause?

Quote:

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the method prevents more than 7 commands being executed.

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How does it do that?

Code :

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if (numoflinesread==Maxlines)
		{
		break;
		}
		return line;
		}
		return line;

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What is that posted code supposed to show?
Why the if statement when the results looks like the code always does a return line?

Look at your inputCommandFile method. You still have it defined to throw an exception but never use a try-catch block or throw anywhere in it.

Your most recent snipped of code breaks out of the while-loop but I think it would always execute return line. In other words, no matter if the condition in the if-statement evaluates to true or false, it's still going to return the same code. Is that intentional?