We Keep Coding

How to compare Strings ignoring cases in Java

Newbie here I am trying to compare the brand and display to an array of Strings. Seems to be working now but I don't know how to make the comparison case-insensitive. All the options I found so far is to compare a string to another string. There is any way I can make that comparison? Right now only accept the values as stated in the array of strings.
P.S. This was an existing homework that our instructor wanted us to build on it, hence why I am using the "isValid" methods for validation.
Thanks!
import com.entertainment.Television;
import java.util.Arrays;
import java.util.Scanner;
class TelevisionConsoleClient {
private static final Scanner scanner = new Scanner(System.in);
public static void main(String[] args) {
welcomeMessage();
}
public static void welcomeMessage() {
//Welcome message to buyer
System.out.println("Welcome to Our Online Ordering System.");
System.out.println("Please answer the questions below to submit your order.");
String brand = brandChoice();
String display = displayChoice();
int size = sizeChoice();
System.out.println("Thank you. The television you ordered is: ");
television(brand, display, size);
//close scanner
scanner.close();
}
public static String brandChoice() {
String brandChoice = null;
boolean hasBrand = false;
while (!hasBrand) {
System.out.println("Please enter the desired brand " + Arrays.toString(Television.VALID_BRANDS) + ":");
brandChoice = scanner.nextLine();
if (Television.isValidBrand(brandChoice))
hasBrand = true;
else
System.out.println("Sorry " + brandChoice + " is not a valid brand");
}
return brandChoice;
}
private static String displayChoice() {
String displayChoice = null;
boolean hasDisplay = false;
while (!hasDisplay) {
System.out.println("Please enter the desired display type " + Arrays.toString(Television.VALID_DISPLAY) + ":");
displayChoice = scanner.nextLine();
if (Television.isValidDisplay(displayChoice))
hasDisplay = true;
else
System.out.println("Sorry " + displayChoice + " is not a valid display type");
}
return displayChoice;
}
private static int sizeChoice() {
Integer sizeChoice = null;
boolean hasSize = false;
while (!hasSize) {
System.out.println("Please enter the desired size " + Arrays.toString(Television.VALID_SIZES) + ":");
sizeChoice = Integer.parseInt(scanner.nextLine());
if (Television.isValidSize(sizeChoice))
hasSize = true;
else
System.out.println("Sorry " + sizeChoice + " is not a valid size");
}
return sizeChoice;
}
private static void television(String brand, String display, int size) {
System.out.println(new Television(brand, display, size));
}
}
package com.entertainment;
public class Television {
// CLASS OR STATIC VARIABLES - STORED IN THE SHARED AREA ASSOCIATED WITH A CLASS
public static final String[] VALID_BRANDS = {"Samsung", "LG", "Sony", "Toshiba"};
public static final String[] VALID_DISPLAY = {"LED", "OLED", "PLASMA", "LCD", "CRT"};
public static final int[] VALID_SIZES = {32, 40, 43, 50, 55, 60, 65, 70, 75, 80};
// FIELDS - AKA 'INSTANCE VARIABLES', 'ATTRIBUTES', 'PROPERTIES'
private String brand;
private String display;
private int size;
// CONSTRUCTORS
// No-arg constructor.
public Television() {
// possible additional "setup" or initialization code here
// want it to run for every instance created
}
// 3-arg constructor
public Television(String brand, String display, int size) {
this.brand = brand;
this.display = display;
this.size = size;
}
// ACCESSOR METHODS (getters/setters)
public String getBrand() {
return brand;
}
public String getDisplay() {
return display;
}
public int getSize() { return size; }
public static boolean isValidBrand(String brand) {
boolean isValid = false;
for (String currentBrand : VALID_BRANDS) {
if (currentBrand.equals(brand)) {
isValid = true;
break;
}
}
return isValid;
}
public static boolean isValidDisplay(String display) {
boolean isValid = false;
for (String currentDisplay : VALID_DISPLAY) {
if (currentDisplay.equals(display)) {
isValid = true;
break;
}
}
return isValid;
}
public static boolean isValidSize(int size) {
boolean isValid = false;
for (int currentSize : VALID_SIZES) {
if (currentSize == size) {
isValid = true;
break;
}
}
return isValid;
}
public String toString() {
return "Television: " + getBrand() + ", Display: " + getDisplay() + ", Size: " + getSize() + " inches.";
}
}

Change String.equals(Object) to String.equalsIgnoreCase(String). That is,
if (currentBrand.equals(brand))
if (currentDisplay.equals(display))
to
if (currentBrand.equalsIgnoreCase(brand))
if (currentDisplay.equalsIgnoreCase(display))

Reduce code duplication when reading different types of numbers from console

I have created three methods readLong, readInt and readDouble that basically does the same thing. Only difference is the method called by a scanner. How can I reduce duplicate code by turning them all to one method?
public long readLong(String description)
{
System.out.println(description);
long nrToReturn = 0;
boolean acceptedValue = false;
do {
System.out.println();
System.out.print("Choose one: ");
try
{
nrToReturn = consoleScanner.nextLong(); //Only line thats different except return value
acceptedValue = true;
}catch(Exception e)
{
acceptedValue = false;
consoleScanner.nextLine();
}
}while (!acceptedValue);
consoleScanner.nextLine();
return nrToReturn;
}

Here we go with one idea:
import java.util.Scanner;
public class ScannerTest {
private Scanner consoleScanner;
public ScannerTest() {
consoleScanner = new Scanner(System.in);
}
#SuppressWarnings("unchecked")
private <T extends Number> T readType(String description, Class<T> desiredType) {
System.out.println(description);
Number result = null;
while (result == null) {
System.out.println();
System.out.print("Choose one: ");
try {
if (Integer.class.equals(desiredType)) {
result = new Integer(consoleScanner.nextInt());
} else if (Long.class.equals(desiredType)) {
result = new Long(consoleScanner.nextLong());
}
} catch(Exception e) {
consoleScanner.nextLine();
}
}
consoleScanner.nextLine();
return (T) result;
}
public long readLong(String description) {
return this.readType(description, Long.class);
}
public int readInt(String description) {
return this.readType(description, Integer.class);
}
public static void main(String[] args) {
ScannerTest t = new ScannerTest();
t.readLong("Reading a long value...");
t.readInt("Reading an integer value...");
}
}
Update, following #Michu93 idea of a single transparent method:
import java.util.Scanner;
public class ScannerTest {
private Scanner consoleScanner;
public ScannerTest() {
consoleScanner = new Scanner(System.in);
}
#SuppressWarnings("unchecked")
public <T extends Number> T readNumber(String description) {
System.out.println(description);
Number result = null;
while (result == null) {
System.out.print("\nChoose one: ");
String textRead = consoleScanner.next();
try {
result = new Integer(textRead);
} catch(Exception e1) {
try {
result = new Long(textRead);
} catch (Exception e2) {
try {
result = new Double(textRead);
} catch (Exception e3) {
}
}
}
consoleScanner.nextLine();
}
return (T) result;
}
public static void main(String[] args) {
ScannerTest t = new ScannerTest();
for (int i = 0; i < 3; i++) {
Number input = t.readNumber(i + ": Reading int, long or double...");
System.out.println("Input class: " + input.getClass().getCanonicalName());
System.out.println("Input value: " + input);
}
}
}

Simple Stack Calculator can't give proper fractional answers

Im trying to fix my code which is a simple calculator in Java made using stacks and a token class. I am having an error every time I have a decimal number as an answer. For example, if I input 11/2 it will give me 1. Its an odd error and I don't know how to fix it and was wondering if someone could tell me how. Thank you for any help!
public class SimpleCalcSkeleton {
private enum TokenType {WS,LP,RP,NUM,OP};
private static class Token {
// instance variables
private String value;
private TokenType type;
// constructor
public Token(String v, TokenType t) {
this.value = v;
this.type = t;
}
// toString() is important for diagnostic output
public String toString() {
return ("[" + value + ";" + type.toString() + "]");
}
// getter or accessor methods for the instance vars or properties
// setter methods are not needed
public String getValue() {
return value;
}
public TokenType getType() {
return type;
}
}
private static TokenType getTokenType(char c) {
TokenType type=null;
if(c==' '){
type=TokenType.WS;
}
if(c=='('){
type=TokenType.LP;
}
if(c==')'){
type=TokenType.RP;
}
if((c=='+')||(c=='-')||(c=='*')||(c=='/')){
type=TokenType.OP;
}
if((c=='0')||(c=='1')||(c=='2')||(c=='3')||(c=='4')||(c=='5')||(c=='6')||(c=='7')||(c=='8')||(c=='9')){
type=TokenType.NUM;
}
return type;
}
private static int getAssoc(Token token) {
String word = token.getValue();
int number =0;
if((word.equals('+'))||(word.equals('-'))){
number=1;
}
if((word.equals('*'))||(word.equals('/'))){
number=2;
}
return number;
}
private static ArrayList<Token> parse(String s) {
if(s==null||s.length()==0){
return null;
}
ArrayList<Token> list= new ArrayList<Token>();
for(int i=0;i<s.length();i++){
char c=s.charAt(i);
TokenType type = getTokenType(c);
String symbol= Character.toString(c);
if(type==null){
System.out.print("Error: null");
}
else if(!type.equals(TokenType.WS)){
list.add(new Token(symbol,type));
}
}
return list;
}
private static ArrayList<Token> infixToPostfix(ArrayList<Token> intokens) {
Stack astack = new Stack();
ArrayList<Token>outokens=new ArrayList<Token>();
for(int i=0;i<intokens.size();i++){
Token in= intokens.get(i);
if(in.getType()==TokenType.NUM){
outokens.add(in);
}
if(in.getType()==TokenType.LP){
astack.push(in);
}
if(in.getType()==TokenType.RP){
Token top=(Token)astack.peek();
while(top.getType()!=TokenType.LP){
astack.pop();
outokens.add(top);
top=(Token)astack.peek();
if(top.getType()==TokenType.LP){
astack.pop();
break;
}}}
if(in.getType()==TokenType.OP){
if(!astack.isEmpty()){
Token top = (Token)astack.peek();
while((top.getType()==TokenType.OP)&&(getAssoc(top)>=getAssoc(in))){
astack.pop();
outokens.add(top);
if(!astack.isEmpty())
top=(Token)astack.peek();
else break;
}}
astack.push(in);
}
}
while(!astack.isEmpty()){
Token top=(Token)astack.peek();
astack.pop();
outokens.add(top);
if(!astack.isEmpty())
top=(Token)astack.peek();
else break;
}
return outokens;
}
private static Token evalOp(Token op, Token t1, Token t2) {
String one = t1.getValue();
String two = t2.getValue();
String opener = op.getValue();
int output =0;
int first = Integer.parseInt(one);
int second = Integer.parseInt(two);
if(opener.equals("+")){
output = second+first;
}
if(opener.equals("-")){
output = second-first;
}
if(opener.equals("*")){
output = second*first;
}
if(opener.equals("/")){
output = second/first;
}
String last = Integer.toString(output);
Token total = new Token(last,TokenType.NUM);
return total;
}
private static String evalPostfix(ArrayList<Token> intokens) {
Stack right = new Stack();
for(int i=0;i<intokens.size();i++){
Token in=intokens.get(i);
if(in.getType()==TokenType.NUM)
right.push(in);
else if(in.getType()==TokenType.OP){
Token at = (Token) right.pop();
Token bat = (Token) right.pop();
Token cat = evalOp(in,at,bat);
right.push(cat);
}
}
return right.toString();
}
public static String evalExpression(String s) {
ArrayList<Token> infixtokens = parse(s);
System.out.println("\tinfix tokens: " + infixtokens);
ArrayList<Token> postfixtokens = infixToPostfix(infixtokens);
System.out.println("\tpostfix tokens: " + postfixtokens);
return evalPostfix(postfixtokens);
}
public static void commandLine() {
Scanner in = new Scanner(System.in);
while (true){
System.out.print("> ");
String word = in.nextLine();
if (word.equals("quit")) {
break;
}
else {
System.out.println(evalExpression(word));
}
}
}
}
class SimpleCalcTest {
public static void test() {
String[] inputs = {
"3*4 + 5",
"3 + 4*5",
"(1+1)*(5-2)",
"(3*4+5)*(3*3 + 4*4)"
};
for (int i=0; i<inputs.length; i++) {
String s = inputs[i];
System.out.println();
System.out.println();
System.out.println("test: input = " + s);
String r = SimpleCalcSkeleton.evalExpression(s);
System.out.println("\tresult = " + r);
}
}
public static void main(String[] args) {
SimpleCalcSkeleton.commandLine();
SimpleCalcTest.test();
}
}

ArrayList and BufferedReader Note Taking Program

I have created a simple program that takes a title and a note which you enter then you have a choice to export the notes to txt file using BufferedWriter however because each note is a object which is stored in a ArrayList when storing them I iterate through a for enhanced loop it keeps duplicating each note as I iterate through all the object.
Note Class
import java.util.*;
public class Notes
{
private String notes;
private String titleOfNotes;
Scanner input = new Scanner(System.in);
public Notes()
{
titleOfNote(input);
takeNotes(input);
}
public void takeNotes(Scanner x)
{
System.out.println("Please Enter Your Note");
notes = x.nextLine();
}
public void titleOfNote(Scanner y)
{
System.out.println("Please Enter Title");
titleOfNotes = y.nextLine();
}
public String toString()
{
return "Title: " + titleOfNotes + "\t" + notes;
}
}
App Class //Does mostof the Work
import java.util.*;
import java.io.*;
public class App
{
private int exit = 0;
private int createANote;
private int displayTheNotes;
private int inputFromUser;
public boolean haveFileBeenWritten = true;
File file = new File("Notes.txt");
Scanner input = new Scanner(System.in);
ArrayList<Notes> arrayOfNotes = new ArrayList<Notes>();
public void makeNoteObject()
{
arrayOfNotes.add(new Notes());
}
public void displayAllTheNote(ArrayList<Notes> n)
{
for(Notes singleObjectOfNote : n)
{
System.out.println(singleObjectOfNote);
}
}
public void programUI(){
while(exit != 1)
{
System.out.println("1. Create A Note");
System.out.println("2. Display The Notes");
System.out.println("3. Exit");
System.out.println("4. Export to text file");
System.out.println("Enter Your Operation");
inputFromUser = input.nextInt();
if(inputFromUser == 1)
{
makeNoteObject();
}
else if(inputFromUser == 2)
{
displayAllTheNote(arrayOfNotes);
}
else if(inputFromUser == 3)
{
System.out.println("Exited");
exit = 1;
}
else if(inputFromUser == 4)
{
makeATxtFileFromNotes(arrayOfNotes);
System.out.println("Textfile created filename: " + file.toString());
}
else
{
System.out.println("You Select A Invalid Command");
}
}
}
public void makeATxtFileFromNotes(ArrayList<Notes> x)
{
try (BufferedWriter bw = new BufferedWriter(new FileWriter(file,haveFileBeenWritten)))
{
//Problem here!
for(Notes singleObjectOfNotes : x)
{
bw.write(singleObjectOfNotes.toString());
bw.newLine();
}
}catch(IOException e)
{
System.out.println("Cant Write File: " + file.toString());
haveFileBeenWritten = false;
}
}
public App()
{
programUI();
}
public static void main(String[]args)
{
App objectOfApp = new App();
}
}
I am new to Java so my code my not be the best!

If your problem is that you only need to see current list's Notes excluding the previous', it's because of this line:
try (BufferedWriter bw = new BufferedWriter(new FileWriter(file,haveFileBeenWritten)))
By default, haveFileBeenWritten is true so based on the FileWriter API it will APPEND on the existing file Notes.txt so if you don't want that, change it to false.
Parameters:
file - a File object to write to
append - if true, then bytes will be
written to the end of the file rather than the beginning
EDIT: To access List<> elements, use get().
Example:
int size = myList.size();
for (int i = 0 ; i < size ; i++) {
//...
Notes note = myList.get(i);
//...
}

Struggling with objects, program does not work as expected(java)

So I have this cyclingmanager game, and I want to show a list of riders by names, and then I want to show their abilities when the user picks a rider. The program compiles and runs nicely, the problem is in my riders() method.It just does not print out c1, my first rider. Thanks in advance.
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class CyclingManager2 {
public static void main(String[] args) {
//menyvalgene
Menu m = new Menu();
m.choice();
}
}
class Menu {
Scanner in = new Scanner(System.in);
Cyclist cy = new Cyclist();
//choices
public void choice() {
int choice = -1;
while (choice != 0) {
System.out.println("Choose something: ");
System.out.println("-0 will exit the program" + "\n-Pressing 1 will open the database menu");
choice = in.nextInt();
switch(choice) {
case 0: choice = 0; break;
case 1: database(); break;
default: System.out.println("You have to choose either 0 or 1"); break;
}
}
}
public void database() {
System.out.println("Welcome to the database \nThese are the options:\n0 = Back to menu\n1: Riders");
int dbChoice = -1;
while (dbChoice != 0) {
System.out.println();
dbChoice = in.nextInt();
switch(dbChoice) {
case 0: dbChoice = 0; break;
case 1: cy.riders(); System.out.println("Press 0 for going back to the menu\nPress 1 for showing the riders");break;
default: System.out.println("Choose either 0 or 1"); break;
}
}
}
}
class Cyclist {
List<Cyclist> cyclists = new ArrayList<>();
private String name;
private int mountain;
private int timeTrial;
private int sprint;
private int age;
Cyclist c1 = null;
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setMountain(int mountain) {
this.mountain = mountain;
}
public int getMountain() {
return mountain;
}
public void setTimeTrial(int timeTrial) {
this.timeTrial = timeTrial;
}
public int getTimeTrial() {
return timeTrial;
}
public void setSprint(int sprint) {
this.sprint = sprint;
}
public int getSprint() {
return sprint;
}
public void setAge(int age) {
this.age = age;
}
public int getAge() {
return age;
}
public void riders() {
abilities();
for (int i = 0; i < cyclists.size(); i++){
System.out.print(((Cyclist) cyclists).getName());
}
}
public void abilities() {
//Pardilla is created
c1 = new Cyclist();
c1.setName("Sergio Pardilla");
c1.setMountain(75);
c1.setTimeTrial(60);
c1.setSprint(60);
c1.setAge(30);
/*System.out.println(c1.getName() + "'s abilities:");
System.out.println("Mountain - " + c1.getMountain());
System.out.println("TimeTrial - " + c1.getTimeTrial());
System.out.println("Sprint - " + c1.getSprint());
System.out.println("Age - " +c1.getAge());
cyclists.add(c1); //adds Pardilla to cyclists arraylist*/
}
}

You have this for-loop:
for (int i = 0; i < cyclists.size(); i++) {
System.out.print(((Cyclist) cyclists).getName());
}
It is not going to work. You are casting the entire cyclists (an ArrayList) to one cyclist instance. You probably want to iterate over the contents of the ArrayList and get each Cyclist-object in the cyclists array. Try a foreach-loop:
for (Cyclist cyclist : cyclists) {
System.out.print(cyclist.getName());
}
or use a for loop with index based retrieval:
for (int i = 0; i < cyclists.size(); i++) {
cyclists.get(i).getName());
}

I think you want more something like:
public void riders() {
abilities();
for (int i = 0; i < cyclists.size(); i++){
System.out.print(cyclists.get(i).getName());
}
}
Another thing, is that I'm not sure you want List<Cyclist> cyclists = new ArrayList<>(); to be part of Cyclist class.

Two issues:
The part where you add your rider to the ArrayList is commented out.
The way you loop over your ArrayList is by no means correct. Try like this:
for (Cyclist cyclist : cyclists) {
System.out.println(cyclist.getName());
}

You should get Objects from List by calling it number: cyclists.get(i).getName())