In my code below I am not sure what order to put it in to work properly.
I first want it to print out for the user to select an option which it does, then if they select 1 it asks them their name and verifies it with the loop etc.
When I enter a name it starts to just loop the question enter your name and I don't know how to fix it.
Do I need to add more statements to my program, if I do then can I still use if statements for the user to select an option?
import java.util.Scanner;
public class username {
public static void main(String[] args) {
{
int UseLift;
int AuditReport;
int ExitLift;
int a;
UseLift = 1;
AuditReport = 2;
ExitLift = 3;
}
System.out.println("choose an option");
System.out.println("Uselift(1)");
System.out.println("see audit report(2)");
System.out.println("Exit Lift(3)");
Scanner d = new Scanner(System.in);
int a = d.nextInt();
Scanner kb = new Scanner(System.in);
// array containing usernames
String[] name = {"barry", "matty", "olly", "joey"}; // elements in array
if (a == 1) {
System.out.println(" Enter your name ");
}
String name1 = kb.nextLine();
boolean b = true;
int j = 0;// counter will start at 0
outerloop:
while (j < 3) {
System.out.println("Enter your name");
}
for (int i = 0; i < name.length; i++) {
if (name[i].equals(name1)) {
System.out.println("you are verified you may use the lift, calling lift ");
}
break;// to stop loop checking names
}
System.out.println("Username Invalid");
j++;
if (a == 2) {
System.out.println("");
}
if (a == 3) {
System.out.println(" Please Exit Lift ");
}
}
}
here you go:
public static void main(String... args) {
String[] verifiedNames = { "barry", "matty", "olly", "joey" };
System.out.println("choose an option");
System.out.println("Uselift(1)");
System.out.println("see audit report(2)");
System.out.println("Exit Lift(3)");
Scanner scanner = new Scanner(System.in);
int choice = scanner.nextInt();
switch (choice) {
case 1:
scanner.nextLine(); // get '\n' symbol from previous input
int nameAttemptsLeft = 3;
while (nameAttemptsLeft-- > 0) {
System.out.println(" Enter your name ");
String name = scanner.nextLine();
if (Arrays.asList(verifiedNames).contains(name)) {
System.out.println("dear " + name + " you are verified " +
"you may use the lift, calling lift ");
break; // break out of loop
}
}
if (nameAttemptsLeft < 0) {
System.out.println("Username Invalid");
}
break;
case 2:
System.out.println("option 2");
break;
case 3:
System.out.println(" Please Exit Lift ");
break;
}
scanner.close();
}
Your while loop below:
while (j < 3) {
System.out.println("Enter your name");
}
will loop forever since j is not incrementing (j++). I believe you've mis-matched your curly braces at some point.
Related
The code that I have runs, but when I do the do-while loop, the for loop does not reset back to 1 when the user chooses Yes to rerun the program. I hope I am making myself clear.
int choice;
int num;
int i;
String input;
int b = 1;
switch (choice) {
case 1:
do {
System.out.println("The starting number is 1.");
//Input
System.out.print("Enter a value: ");
num = sc.nextInt();
for (i = 1; i <= num; i++) {
b = b * i;
//Output
System.out.printf("%d! = %d\n", i, b);
}
System.out.print(
"Run the program again? (Y for Yes, N for No): ");
input = sc.next();
} while (input.equalsIgnoreCase("Y"));
if (input.equalsIgnoreCase("N")) {
System.out.println(
"Have a great day!");
System.exit(0);
}
break;
}
I tried a while loop instead of the for loop and I was not getting the results at all. I am new to Java so I am still learning.
I added a break at the end of the for loop, but that ends the loop only after 1 increment.
You don't need a switch expression. Also, declare the variables in the narrowest scope. In this case, except for sc, they should be declared in the do/while loop, or in the case of b, in the for loop.
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
do {
System.out.println("The starting number is 1.\n");
System.out.print("Enter a value: ");
// Input
int num = sc.nextInt();
for (int i = 1, b = 1; i <= num; i++) {
b = b * i;
// Output
System.out.printf("%d! = %d\n", i, b);
}
System.out.print(
"Run the program again? (Y for Yes, N for No): ");
String input = sc.next();
if (input.equalsIgnoreCase("N")) {
System.out.println(
"Have a great day!");
sc.close();
System.exit(0);
}
} while (true);
}
I'm new to Java and attempting this question where I'm supposed to input a pair of values (two strings one at a time) which is meant to loop until I've exited using ctrl z. Only the grade will be used for the switch; the name is just a dummy value.
My expected output will be:
Enter name: (Name is then entered)
Enter grade: (Grade is then entered)
Code repeats until EOC is hit.
What is the most effective way to implement a working loop using while (.hasNext())? The code I've tried to make is very flawed, as seen below.
public static void main(String[] args) {
int ACount = 0;
int BCount = 0;
int CCount = 0;
int DCount = 0;
Scanner input = new Scanner(System.in);
while(input.hasNext()) {
System.out.print("\nEnter name: ");
String nameInput = input.next();
System.out.print("Enter grade: ");
String gradeInput = input.next();
switch (gradeInput) {
case "A":
ACount++;
break;
case "B":
BCount++;
break;
case "C":
CCount++;
break;
case "D":
DCount++;
break;
}
}
System.out.printf("%n%nGrade report%n%nA: %d%nB: %d%nC: %d%nD: %d%n", ACount, BCount, CCount, DCount);
}
I think this solution is what you are looking for, it switches between asking for the name and grade until you cancel it with ctrl + z. Personally I have been coding java for 4 years and never used a switch, so I just used simple if-else statements, also by using just print, not println, the phrase was getting into the var, which is the reason of me using println.
public static void main(String[] args) {
int ACount = 0;
int BCount = 0;
int CCount = 0;
int DCount = 0;
Scanner input = new Scanner(System.in);
boolean askingForName = false;
boolean first = true;
System.out.println("Enter name: ");
while(true) {
if (first) {
String nameInput = input.nextLine();
first = false;
continue;
}
if (askingForName) {
System.out.println("Enter name: ");
String nameInput = input.nextLine();
askingForName = false;
}else {
System.out.println("Enter grade: ");
String gradeInput = input.nextLine();
if (gradeInput.equalsIgnoreCase("A")) {
ACount++;
}else if (gradeInput.equalsIgnoreCase("B")) {
BCount++;
}else if (gradeInput.equalsIgnoreCase("C")) {
CCount++;
}else if (gradeInput.equalsIgnoreCase("D")) {
DCount++;
}
askingForName = true;
}
if (!input.hasNextLine())
break;
}
System.out.printf("%n%nGrade report%n%nA: %d%nB: %d%nC: %d%nD: %d%n", ACount, BCount, CCount, DCount);
}
I have just started learn java codes, that is why might I have a simple question that is not simple for me.
I would like put a optional "wrong number. Try again" when is entered different number than secretNum. May you guys help me out on this code?
// I need learn how put "try again" when the number is != than guess number.
/* I have tried
* 1)Change the signal "==" or "!=".
* 2) do {
System.out.println("Guess what is the number 0 to 10: ");
if (sc.hasNextInt()) {
guess = sc.nextInt();
}
} while(secretNum != guess);{
System.out.println("Well done");
System.out.println();
System.out.println("Are you ready for the next step?");
System.out.println();
}
*/
import java.util.Scanner;
public class GuessNumber {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter name:");
if(sc.hasNextLine()) {
String userName = sc.nextLine();
System.out.println("Hello " + userName + ",");
System.out.println();
}
int secretNum = 5;
int secretNum2 = 15;
int guess = 0;
do {
System.out.println("Guess what is the number 0 to 10: ");
if (sc.hasNextInt()) {
guess = sc.nextInt();
}
} while(secretNum != guess);{
System.out.println("Well done\n");
System.out.println("Are you ready for the next step?\n");
}
// I need learn how put "try again" when the number is != than guess number.
/* I have tried
* 1)Change the signal "==" or "!=".
* 2) do {
System.out.println("Guess what is the number 0 to 10: ");
if (sc.hasNextInt()) {
guess = sc.nextInt();
}
} while(secretNum != guess);{
System.out.println("Well done");
System.out.println();
System.out.println("Are you ready for the next step?");
System.out.println();
}
*/
System.out.println("Enter Yes or No");
while(!sc.next().equals("yes")&& !sc.next().equals("no"));{
System.out.print("Yes");
}
do {
System.out.println("Guess what is the number 11 to 20: ");
if (sc.hasNextInt()) {
guess = sc.nextInt ();
}
}while(secretNum2 != guess);{
System.out.println("Congratulations");
System.out.println();
System.out.println("The End");
}
}
}
````````
You don't need do{} while() for the checks you want to do here, just while(){} loops would be enough.
Please try this code instead:
import java.util.Scanner;
public class GuessNumber {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter name:");
if (sc.hasNextLine()) {
String userName = sc.nextLine();
System.out.println("Hello " + userName + ",");
System.out.println();
}
int secretNum = 5;
int secretNum2 = 15;
int guess = 0;
System.out.println("Guess what is the number 0 to 10: ");
if (sc.hasNextInt()) {
guess = sc.nextInt();
}
while (secretNum != guess) {
System.out.println("Please try again\n");
if (sc.hasNextInt()) {
guess = sc.nextInt();
}
}
System.out.println("Well done\n");
System.out.println("Are you ready for the next step?\n");
System.out.println("Enter Yes or No");
while (!sc.next().equals("yes") && !sc.next().equals("no"))
{
System.out.print("Yes");
}
System.out.println("Guess what is the number 11 to 20: ");
if (sc.hasNextInt()) {
guess = sc.nextInt();
}
while (secretNum2 != guess) {
System.out.println("Please try again\n");
if (sc.hasNextInt()) {
guess = sc.nextInt();
}
}
System.out.println("Congratulations");
System.out.println();
System.out.println("The End");
}
}
public static void modifyBall(String[] hookPotentialArray, String[] nameBallArray, int[] ballWeightArray, int count) {
Scanner keyboard = new Scanner(System.in);
System.out.println("Please enter the name of the ball you would like to modify: ");
String name = keyboard.nextLine();
for (int i = 0; i < count; i++) {
if (name.compareToIgnoreCase(nameBallArray[i]) == 0) {
System.out.println("Please enter a new name for the ball: ");
String ballName = keyboard.nextLine();
System.out.println("Please enter a new weight for the ball: ");
int ballWeight = keyboard.nextInt();
System.out.println("Please enter a new hook potential for the ball: ");
String hookPotential = keyboard.next();
nameBallArray[i] = ballName;
ballWeightArray[i] = ballWeight;
hookPotentialArray[i] = hookPotential;
System.out.println("The ball list has been updated.");
System.out.println("");
}
}
You should refactor to separate the loop for finding/not finding the ball (or not), and do whatever you need to do with the ball (or error if not found) OUTSIDE the loop. This helps with readability because more of your lines are less indented, and it helps communicate your intent because most of your code in the loop is only going to be executed once anyway.
int ballIndex = -1;
for (int i = 0; i < count; i++) {
if (name.compareToIgnoreCase(nameBallArray[i]) == 0) {
ballIndex = nameBallArray[i];
break;
}
}
if (ballIndex >= 0) {
// found - do everything using ballIndex
} else {
// not found - display error
}
Set a flag variable to 0 before loop. Inside if set it 1. After the loop check if it is still zero. then print appropriate message that no item found.
Boolean flag = false; // before loop
flag = true; //inside if
// After loop
if(!flag)
System.out.println("Not Found");
Try this:
public static void modifyBall(String[] hookPotentialArray, String[] nameBallArray, int[] ballWeightArray, int count) {
Scanner keyboard = new Scanner(System.in);
System.out.println("Please enter the name of the ball you would like to modify: ");
String name = keyboard.nextLine();
for (int i = 0; i < count; i++) {
if (name.compareToIgnoreCase(nameBallArray[i]) == 0) {
System.out.println("Please enter a new name for the ball: ");
String ballName = keyboard.nextLine();
System.out.println("Please enter a new weight for the ball: ");
int ballWeight = keyboard.nextInt();
System.out.println("Please enter a new hook potential for the ball: ");
String hookPotential = keyboard.next();
nameBallArray[i] = ballName;
ballWeightArray[i] = ballWeight;
hookPotentialArray[i] = hookPotential;
System.out.println("The ball list has been updated.");
System.out.println("");
return;
}
}
System.out.println("ball not found");
}
You could create a boolean and set it to true in your if statement that means it's been found. You could check the boolean after loop to see if it's true or false then display error message if true.
Example:
public static void modifyBall(String[] hookPotentialArray, String[] nameBallArray, int[] ballWeightArray, int count) {
boolean found = false; //boolean for if it's found or not
Scanner keyboard = new Scanner(System.in);
System.out.println("Please enter the name of the ball you would like to modify: ");
String name = keyboard.nextLine();
for (int i = 0; i < count; i++) {
if (name.compareToIgnoreCase(nameBallArray[i]) == 0) {
found = true; //set boolean if found
System.out.println("Please enter a new name for the ball: ");
String ballName = keyboard.nextLine();
System.out.println("Please enter a new weight for the ball: ");
int ballWeight = keyboard.nextInt();
System.out.println("Please enter a new hook potential for the ball: ");
String hookPotential = keyboard.next();
nameBallArray[i] = ballName;
ballWeightArray[i] = ballWeight;
hookPotentialArray[i] = hookPotential;
System.out.println("The ball list has been updated.");
System.out.println("");
break; //break out of loop if item found
}
}
//check if boolean is false then print error message
if (!found)
{
System.out.println("There was a problem finding your item.");
}
I also added a break at end of if statement to break out of the loop if the item was found(no point in continuing on if the item was already found).
I have four classes but they're just templates so I'll only post my main class (I have overridden toString for each). The sort method is at the bottom. Everything else is fine (more or less) with my code, but when I create the objects in the array and then go to sort them (by a string value called uid) sometimes one or two of them will be out of order. How can I fix this?
Here's the code:
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.InputMismatchException;
import java.util.Scanner;
enum ClassStanding{FRESHMAN,SOPHOMORE,JUNIOR,SENIOR,UNKNOWN,MASTERS_STUDIES,PHD_STUDIES};
enum Major{CS,CEG,EE,ISE,BME,ME,MET,UNKNOWN};
enum StudentType{UNDERGRADUATE,GRADUATE,UNDECLARED};
public class Main {
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
Scanner stdin = new Scanner(System.in);
ArrayList<Student> studentList = new ArrayList<>();
int counter;
boolean continueInput;
int contCounter;
do {
do {
System.out.print("Please enter what you want to do-ADD, REMOVE, SORT, LIST, or SAVE: ");
switch (stdin.next().toLowerCase()) {
case "add":
add(stdin, studentList);
counter = 0;
break;
case "remove":
remove(studentList, stdin);
counter = 0;
break;
case "list":
list(studentList);
counter = 0;
break;
case "save":
String fileName = getFileName(stdin);
save(fileName, studentList);
counter = 0;
break;
case "sort":
counter = 0;
sort(studentList);
break;
default:
System.out.println("Improper input, please enter only ADD, REMOVE, LIST, or SAVE.");
counter = 1;
}
} while (counter == 1);
do {
System.out.print("\nDo you want to continue? Yes or no: ");
switch (stdin.next().toLowerCase()) {
case "yes":
contCounter = 0;
continueInput = true;
break;
case "no":
contCounter = 0;
continueInput = false;
break;
default:
contCounter = 1;
continueInput = false;
System.out.print("\nPlease only enter 'yes' or 'no'.");
}
} while (contCounter == 1);
} while (continueInput);
} // end main method
public static void add(Scanner stdin, ArrayList<Student> studentList) {
String firstName;
String lastName;
String uid;
StudentType studentType;
ClassStanding studentClassStanding;
Major major;
double overallGPA;
double majorGPA;
String majorProfessor;
boolean thesisOption;
System.out.print("Please enter the student's first name: ");
String tempName = stdin.next();
firstName = checkName(tempName);
System.out.print("Please enter the student's last name: ");
tempName = stdin.next();
lastName = checkName(tempName);
System.out.println("Please enter the student's UID in the format 'U####' or 'U#####': ");
String tempUID = stdin.next();
uid = checkUID(tempUID).toUpperCase();
int count;
do {
System.out.print("Please enter the student's status as UNDECLARED, UNDERGRADUATE, or GRADUATE: ");
switch (stdin.next().toUpperCase()) {
case "UNDECLARED":
studentType = StudentType.UNDECLARED;
studentClassStanding = setStudentClassStanding(studentType);
count = 0;
Student student = new Student(firstName, lastName,
uid, studentType, studentClassStanding);
studentList.add(student);
break;
case "UNDERGRADUATE":
studentType = StudentType.UNDERGRADUATE;
major = setMajor();
studentClassStanding = setStudentClassStanding(studentType);
System.out.println("Enter the student's overall GPA below.");
overallGPA = setGPA();
System.out.println("Enter the student's major GPA below.");
majorGPA = setGPA();
count = 0;
UnderGraduate underGraduate = new UnderGraduate(firstName, lastName, uid, studentType,
studentClassStanding, major, overallGPA, majorGPA);
studentList.add(underGraduate);
break;
case "GRADUATE":
studentType = StudentType.GRADUATE;
studentClassStanding = setStudentClassStanding(studentType);
majorProfessor = setMajorProfessor();
thesisOption = setThesisOption();
count = 0;
Graduate graduate = new Graduate(firstName, lastName, uid, studentType,
studentClassStanding, majorProfessor, thesisOption);
studentList.add(graduate);
break;
default:
System.out.println("Please enter either Undeclared, Undergraduate, or Graduate only.");
count = 1;
}
} while (count == 1);
} // end add method
public static String checkName(String tempName) {
int a = 1;
String name1;
Scanner scanner = new Scanner(System.in);
do {
name1 = tempName; // hold the value of firstName in name1
for (int i = 0; i < tempName.length(); i++) { // loop to check input consists of letters (is a name)
if (!Character.isLetter(tempName.charAt(i))) { // if non-letters detected, ensure this was intentional
System.out.println("Please ensure you've entered the correct name. Re-enter the name or enter 'continue' to proceed: ");
tempName = scanner.nextLine();
if (tempName.equalsIgnoreCase("continue")) { // if user enters "continue", use original input
a = 0;
tempName = name1; // pass name1 value to firstName
break;
} else {
a = 1; // continue prompting for firstName
}
} else { // accept input
a = 0;
}
}
} while (a == 1); // loop to ensure proper input
return tempName;
} // end checkName method
public static String checkUID(String tempUID) {
Scanner scan = new Scanner(System.in);
int a;
do {
if (tempUID.charAt(0) == 'U' || tempUID.charAt(0) == 'u') {
if (tempUID.length() == 6 || tempUID.length() == 5) {
a = 0;
} else {
a = 1;
System.out.print("Please ensure input is in the form of U#### or U#####. Please re-enter the UID: ");
tempUID = scan.next();
}
} else {
a = 1;
System.out.print("Please ensure input is in the form of U#### or U#####. Please re-enter the UID: ");
tempUID = scan.next();
}
} while (a == 1);
return tempUID;
} // end checkUID method
public static ClassStanding setStudentClassStanding(StudentType studentType) {
Scanner scan = new Scanner(System.in);
int count;
ClassStanding studentTempClassStanding = null;
do {
if (studentType == StudentType.UNDECLARED || studentType == StudentType.UNDERGRADUATE) {
System.out.print("Please enter the student's class standing as either Freshman, Sophomore, Junior, Senior, or Unknown: ");
switch (scan.next().toUpperCase()) {
case "FRESHMAN":
studentTempClassStanding = ClassStanding.FRESHMAN;
count = 0;
break;
case "SOPHOMORE":
studentTempClassStanding = ClassStanding.SOPHOMORE;
count = 0;
break;
case "JUNIOR":
studentTempClassStanding = ClassStanding.JUNIOR;
count = 0;
break;
case "SENIOR":
studentTempClassStanding = ClassStanding.SENIOR;
count = 0;
break;
case "UNKNOWN":
studentTempClassStanding = ClassStanding.UNKNOWN;
count = 0;
break;
default:
System.out.println("Please enter only Freshman, Sophomore, Junior, Senior, or Unknown.");
count = 1;
}
} else {
System.out.print("Please enter the student's class standing as either 'Masters' for Masters Studies or 'PhD' for PhD Studies: ");
switch (scan.next().toUpperCase()) {
case "MASTERS": studentTempClassStanding = ClassStanding.MASTERS_STUDIES; count = 0; break;
case "PHD": studentTempClassStanding = ClassStanding.PHD_STUDIES; count = 0; break;
default: System.out.println("Please enter only 'Masters' or 'PhD'.");
count = 1;
}
}
} while (count == 1);
return studentTempClassStanding;
} // end setStudentClassStanding method
public static Major setMajor() {
Major tempMaj = null;
Scanner s = new Scanner(System.in);
int c;
do {
System.out.print("Please enter the student's major as either CS, CEG, EE, ISE, BME, ME, MET, or Unknown: ");
switch (s.next().toUpperCase()) {
case "CS":
tempMaj = Major.CS;
c = 0;
break;
case "CEG":
tempMaj = Major.CEG;
c = 0;
break;
case "EE":
tempMaj = Major.EE;
c = 0;
break;
case "ISE":
tempMaj = Major.ISE;
c = 0;
break;
case "BME":
tempMaj = Major.BME;
c = 0;
break;
case "ME":
tempMaj = Major.ME;
c = 0;
break;
case "MET":
tempMaj = Major.MET;
c = 0;
break;
case "UNKOWN":
tempMaj = Major.UNKNOWN;
c = 0;
break;
default:
System.out.println("Please enter only the specified values. ");
c = 1;
}
} while (c == 1);
return tempMaj;
} // end setMajor method
public static double setGPA() {
Scanner s = new Scanner(System.in);
double gpa;
int a;
do {
try {
System.out.print("Please enter the student's GPA: ");
gpa = s.nextDouble();// read in the gpa
if (gpa < 0.0 || gpa > 4.0) { // ensure the gpa is in the correct range
System.out.println("Invalid input, please enter a positive value between 0.0 and 4.0.");
a = 1;
} else {
a = 0;
}
} catch (InputMismatchException ex) { //catch any exceptions, prompt for correct input
a = 1;
gpa = 0.0;
System.out.println("Sorry, please enter a double value.");
s.nextLine(); // skip the last input
}
} while (a == 1 || gpa < 0.0 || gpa > 4.0); //loop while gpa is negative or incorrect input is received
return gpa;
} // end setGPA method
private static String setMajorProfessor() {
Scanner s = new Scanner(System.in);
String prof;
System.out.print("Please enter the name of the major professor: ");
String tempName = s.nextLine();
prof = checkName(tempName);
return prof;
} // end setMajorProfessor method
private static boolean setThesisOption() {
Scanner s = new Scanner(System.in);
boolean thesis = false;
int a;
do {
System.out.print("Please enter 'yes' if a thesis will be written, otherwise enter 'no': ");
switch (s.next().toUpperCase()) {
case "YES": thesis = true; a = 0; break;
case "NO": thesis = false; a = 0; break;
default: System.out.println("Please enter only 'yes' or 'no'."); a = 1;
}
} while (a == 1);
return thesis;
} // end setThesisOption method
private static void list(ArrayList<Student> studentList) {
for (int i = 0; i < studentList.size(); i++) {
System.out.println(studentList.get(i).toString());
}
} // end list method
public static String getFileName(Scanner stdin) {
System.out.print("Please enter the file name: "); // Prompt for input
String fileString = stdin.next();
return fileString; // Pass the fileString var to the main method
}//end of getFileName method
private static void save(String fileName, ArrayList<Student> studentList) {
int a; // create a counter
Scanner stdin = new Scanner(System.in);
do {
try {
PrintWriter writer = new PrintWriter(fileName); // Create a printwriter
for (int i = 0; i < studentList.size(); i++) {
writer.print(studentList.get(i).toString() + "\n"); //Print the arraylist to file
}
writer.close(); //Close the printwriter and save the file
a = 0;
} catch (FileNotFoundException ex) { // Catch any exceptions
System.out.println("The file could not be found, please re-enter the file name: "); // get new file name if an exception is thrown
fileName = stdin.nextLine();
a = 1;
}
} while (a == 1); // loop while exceptions are thrown
System.out.println("All information has been saved at " + fileName); // output that the arraylist has been saved in the specified file
// Make the following its own method
System.out.print("Would you like to read the contents of the file? Yes or no: ");
int b;
do {
switch (stdin.next().toLowerCase()) {
case "yes": readFromFile(fileName); b = 0; break;
case "no": b = 0; break;
default: System.out.println("Please enter only yes or no."); b = 1;
}
} while (b == 1);
} // end save method
private static void remove(ArrayList<Student> studentList, Scanner stdin) {
System.out.print("Please enter the UID of the student to be removed: ");
String tempUID = stdin.next();
String uidRemove = checkUID(tempUID);
for (int i = 0; i < studentList.size(); i++) {
if ((studentList.get(i).getUid()).equalsIgnoreCase(uidRemove)) {
studentList.remove(i);
}
}
System.out.println("The student with UID " + uidRemove + " has been removed.");
} // end remove method
private static void sort(ArrayList<Student> studentList) {
String uidLessU1;
String uidLessU2;
for (int i = 0; i < studentList.size(); i++) {
uidLessU1 = (studentList.get(i).getUid()).substring(1, studentList.get(i).getUid().length());
for (int j = 0; j < studentList.size(); j++) {
uidLessU2 = (studentList.get(j).getUid()).substring(1, studentList.get(j).getUid().length());
if (Integer.parseInt(uidLessU1) < Integer.parseInt(uidLessU2)) {
Student hold = studentList.get(i);
studentList.set(i, studentList.get(j));
studentList.set(j, hold);
}
}
}
} // end sort method
private static void readFromFile(String fileName) {
System.out.println("The contents of " + fileName + " as read from NotePad: ");
try {
Scanner fileReader = new Scanner(new File(fileName)); //Create a scanner
while (fileReader.hasNextLine()) { //Loop to read the file
String fromFile = fileReader.nextLine();
System.out.println(fromFile); //Output the file contents
}
} catch (FileNotFoundException ex) { //Catch any exceptions
System.out.println("Exception caught");
}
} // end readFromFile method
} // end main class
A sample of the problem would be (at this point I've already entered all the values instantiating the objects):
Do you want to continue? Yes or no: yes
Please enter what you want to do-ADD, REMOVE, SORT, LIST, or SAVE: list
Student s w whose UID is U3333 is a
UNDECLARED student doing JUNIOR work.
Student p o whose UID is U1111 is a
UNDECLARED student doing JUNIOR work.
Student p u whose UID is U44444 is a
UNDECLARED student doing JUNIOR work.
Student w e whose UID is U4444 is a
UNDECLARED student doing JUNIOR work.
Student s r whose UID is U2222 is a
UNDECLARED student doing JUNIOR work.
Student s u whose UID is U7777 is a
UNDECLARED student doing JUNIOR work.
Student po iu whose UID is U77777 is a
UNDECLARED student doing JUNIOR work.
Do you want to continue? Yes or no: yes
Please enter what you want to do-ADD, REMOVE, SORT, LIST, or SAVE: sort //calls the sort method
Do you want to continue? Yes or no: yes
Please enter what you want to do-ADD, REMOVE, SORT, LIST, or SAVE: list // calls the list method and prints out the arraylist
Student p o whose UID is U1111 is a
UNDECLARED student doing JUNIOR work.
Student s r whose UID is U2222 is a
UNDECLARED student doing JUNIOR work.
Student s w whose UID is U3333 is a
UNDECLARED student doing JUNIOR work.
Student s u whose UID is U7777 is a //why is this out of place?
UNDECLARED student doing JUNIOR work.
Student w e whose UID is U4444 is a
UNDECLARED student doing JUNIOR work.
Student p u whose UID is U44444 is a
UNDECLARED student doing JUNIOR work.
Student po iu whose UID is U77777 is a
UNDECLARED student doing JUNIOR work.
Just make Student implement Comparable and then you can do
Collections.sort(studentList);