File IO

Question 1

What is TextInputFile?

Answer 1

storage command provided by arc library to read files

Question 2

What is TextOutputFile?

Answer 2

storage command provided by arc library to write files

Question 3

It is good practice to…

Answer 3

close your txt files after using them

Question 4

Function of:

TextInputFile variablename = TextInputFile(“filename.txt”);

Answer 4

Storage Command
* tells computer to open up the specific file from the hard drive/storage
* gives the file name a variable which can be used throughout program

Question 5

How do you check to see if your code can open the file?

Answer 5

if no error message appears in the background window

Question 6

Does variable name for TextInputFile or TextOutputFile have to match the text file?

Answer 6

No

Question 7

Function of Storage Input Command

Answer 7

tells the computer to read a line from the already opened file

Question 8

tells the computer to read a line from the already opened file

Answer 8

Function of Storage Input Command

Question 9

Write the line of code to open text file for reading

Answer 9

TextInputFile variablename = new TextInputFile(“textfilename.txt”);

Question 10

Write the line of code to open a text file for writing

Answer 10

TextOutputFile variablename = new TextOutputFile(“textfilename.txt”);

Question 11

Write an example of a Storage Input Command for any variable type

Answer 11

strLine = txtvariablename.readLine();

intLine = txtvariablename.readInt();

dblLine = variablename.readDouble();

Question 12

Write a line of code to close the opened text file

Answer 12

textvariablename.close();

Question 13

Function of .eof()

Answer 13

Method which means “End of File”
* looks for a blank line b/w lines or at the end of text and identifies it as the end of code

Question 14

Write the general structure to read every line of code in a file (as a string)

Answer 14

while(textvariablename.eof() == false) {
strLine = textvariablename.readLine();
}

Question 15

What is it good practice to do when finished with a file?

Answer 15

to close it

Question 16

If file format is:
* Course Name
* Course Mark
* Course Name
* Course Mark …

How do you print just the course name?

Answer 16

1. Read all lines
2. Print just the course name variable

Question 17

Function Storage Output Command

Answer 17

tells computer to print whatever is in quotes or in the variable to the opened text file

Question 18

Write an example of a Storage Output Command

Answer 18

filevariablename.println(“quotes” + intVariable);

Question 19

Function of:

TextOutputFile variablename = new TextOutputFile(“filename.txt”);

Answer 19

Storrage Command
* tells hard drive/storage to create a new text file (or clear and edit existing file) called filename.txt for writing

Question 20

Function of:

TextOutputFile variablename = new TextOutputFile(“filename.txt”, true);

Answer 20

Storage Command
* tells hard drive/storage to create a new text file (or edit existing file) called filename.txt for writing
* any new data will be appended (added) to the bottom of the opened text file

Question 21

Function of “, true”

Answer 21

Appends any new data to the bottom of the text file

Question 22

Write a program that will read every line from the file canadapm.txt but only print all the data for a specific Prime Minister.
Example: If the user types “Pierre Trudeau,” the program should only display data related to Pierre Trudeau.

Answer 22

import arc.*;

public class iohw4{
public static void main(String [] args){
Console con = new Console();
// Read every line
// Print data from specific prime minister that user chooses

	// Open txt
	TextInputFile canadapm = new TextInputFile("canadapm.txt");
	
	// Variables
	String strPM;
	int intBirthYr;
	int intDeathYr;
	int intElectYr;
	int intResignYr;
	String strParty;
	String strInput;
	
	// Input
	con.println("This file contains data on all the Canadian prime ministers.");
	con.print("Choose a Prime Minister to learn more about: ");
	strInput = con.readLine();
	
	// Read & Print
	while(canadapm.eof() == false){
		strPM = canadapm.readLine();
		intBirthYr = canadapm.readInt();
		intDeathYr = canadapm.readInt();
		intElectYr = canadapm.readInt();
		intResignYr = canadapm.readInt();
		strParty = canadapm.readLine();
		
		if(strPM.equalsIgnoreCase(strInput)){
			con.println("Birth year: " + intBirthYr);
			if(intDeathYr == 0){
				con.println("Alive :)");
			}else{
				con.println("Death year: " + intDeathYr);
			}
			con.println("Elected in: " + intElectYr);
			if(intResignYr == 0){
				con.println("Still Active");
			}else{
				con.println("Resigned in: " + intResignYr);
			}
			con.println("Party: " + strParty);
		}
	}
	canadapm.close();
			
} }

Question 23

Write a program that reads every name from the file bff.txt and prints them to the screen.
After reading, open the file for writing, ask the user for one more friend’s name, and append it to the end of the file.

Answer 23

import arc.*;

public class iohw6{
public static void main(String [] args){
Console con = new Console();

	// Read every name from bff.txt
	// Print names
	// add one more name (without erasing)
	
	//open filee
	TextInputFile bff = new TextInputFile("bff.txt");
	
	//variables
	String strFriend;
	
	con.println("These are the people currently on your friends list");
	while(bff.eof() == false){
		strFriend = bff.readLine();
		con.println(strFriend);
	}
	bff.close();
	
	
	TextOutputFile addbff = new TextOutputFile("bff.txt", true);
	//add name
	con.print("Add a name to your friends list: ");
	strFriend = con.readLine();
	addbff.println(strFriend);
	
	addbff.close();
	
	//do I have to close both? 
		//close txt after using
	
	con.println();
	con.println("added!");
	
	
} }

Question 24

Write a program that asks for the names of your best friends and writes them to a file called bff.txt.
Stop writing names and close the file when the user types “stop.”

Answer 24

import arc.*;

public class iohw5{
public static void main(String [] args){
Console con = new Console();

	// write names of friends to a file called bff.txt
	// stop adding names when user types stop
	// close file
	
	TextOutputFile addfriend = new TextOutputFile("bff.txt");
	
	String strFriendo = "";
	
	while(!strFriendo.equalsIgnoreCase("stop")){
		con.println("Who would you like to add to your friend's list? (Enter \"stop\" to end program)");
		strFriendo = con.readLine();
		
		addfriend.println(strFriendo);
		con.println();
	}
	
	addfriend.close();
	con.println("closed bff.txt");
} }