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How to get my FileWriter to find the next available line than write below that

So I have seen alot of similar questions to this one but can't seem to find the answer so sorry if this is a duplicate. So I am creating a java program for black jack that I would like to have a system in place to save the chips the user has. I can get it to work but whenever I try to get it to save it just seems to overwrite what was already previously there.
Example
User enters there name: Bob
The system automatically knows there chips so when they press the button to save game it writes there name and chips like so...
Bob
200 (or however many chips they have)
The problem comes up when a new user enters there name and saves so say sally was saving instead of going
Bob
200
Sally
300
It does
Sally
300
And completly deletes bob
public void newSave(String user){
this.user = user;
user = user;
String Chip = Integer.toString(chips);
try{
FileWriter fileWriter = new FileWriter(file);
fileWriter.write(user);
fileWriter.write("\n");
fileWriter.write(Chip);
fileWriter.close();
}
catch(Exception e){
System.out.println(e.getMessage());
}
}
Here is my code that I have that is where my issue lies.
Here is the whole code of the program method.
import java.util.*;
import java.io.*;
class BlackJackPlayer{
//Keep the data secure by using private
private String hand;
private String user;
private int betNum;
private int sum;
private int numAces;
private int chips = 100;
private String bet;
private static Random gen = new Random();
private String result = "";
public String Win = "Win", Lose = "Lose", Split = "Split";
private final int ACE = 1;
private final int JACK = 11;
private final int QUEEN = 12;
private final int KING = 13;
//Scanner for fileIn
Scanner fileIn;
//File For Saves!
File file = new File("Saves.txt");
//Array For Saves!
private ArrayList<String> User = new ArrayList<>();
private ArrayList<Integer> Chips = new ArrayList<>();
//constructor
public BlackJackPlayer(){
hand = "";
sum = 0;
numAces = 0;
//Create a file if save file does not exist//
try{
if (file.createNewFile()){
System.out.println("Save File Created!");
}
else{
//Say Nothing//
}
}//End Try
catch(Exception e){
System.out.println(e.getMessage());
}
//End File Create//
//Read File //
try{
fileIn = new Scanner(new FileReader(file, true));
while(fileIn.hasNext()){
User.add( fileIn.nextLine().trim() );
Chips.add( fileIn.nextInt() );
}//End While
fileIn.close();
}//End Try
catch(Exception e){
System.out.println(e.getMessage());
}//End Catch
//End Read File//
}//End public
//checkSaveStatus//
//See if save exists already in text than send to proper scenario//
public boolean checkSaveStatus(String user){
for(String u: User){
if (user == u){
return true;
}//end if
}//end for
return false;
}//end checkSaveStatus
//End checkSaveStatus//
//overWriteSave if save already exists//
public void overWriteSave(String user){
}//end overWriteSave
//End overWriteSave//
//newSave scnenario if save dosent exist//
public void newSave(String user){
this.user = user;
user = user;
String Chip = Integer.toString(chips);
try{
FileWriter fileWriter = new FileWriter(file);
fileWriter.write(user);
fileWriter.write("\n");
fileWriter.write(Chip);
fileWriter.close();
}
catch(Exception e){
System.out.println(e.getMessage());
}
}
public boolean checkBet(String bet, int chips){
this.bet = bet;
int betNum = Integer.parseInt(bet);
if(betNum <= chips){
return true;
}
return false;
}
public String setBet(String bet){
this.bet = bet;
betNum = Integer.parseInt(bet);
return "You Bet: " + betNum;
}
public String updateChips(){
chips -= betNum;
return "You have: " + chips + " chips";
}
//Getter for hand variable
public String getHand(){
return hand;
}
public String setHand(){
hand = " ";
return hand;
}
//Getter for sum variable
public int getSum(){
return sum;
}
public void hit(){
//local variable
int currentCard = gen.nextInt(13) + 1;
if(currentCard > ACE && currentCard < JACK){
sum += currentCard;
hand += currentCard + " ";
}
else if(currentCard == ACE){
sum += 11;
numAces++;
hand += "A ";
}
else if(currentCard == QUEEN){
sum += 10;
hand += "Q ";
}
else if(currentCard == QUEEN){
sum += 10;
hand += "Q ";
}
else if(currentCard == KING){
sum += 10;
hand += "K ";
}//Ends Else If
//Is Ace 1 or 11
if(sum > 21 && numAces > 0){
numAces--;
sum -= 10;
}
}//ENDS HIT
public void stand(){
sum = sum;
return;
}//ends stand
public String getWin(BlackJackPlayer other) {
if(sum > 21){
result = Win;
}
else if(sum < other.getSum()){
result = Lose;
}
else if(sum == other.getSum()){
result = Split;
}
return result;
}
}//end class

Use following code.
FileWriter fileWriter = new FileWriter(file, true);
Here true signifies that you want to append data to existing file.
For more details : https://docs.oracle.com/javase/7/docs/api/java/io/FileWriter.html#FileWriter(java.io.File,%20boolean)

Printing the value and position of an array from a method

I am working on a program that takes user input for an array. One method I have FindLowestTempInArray returns the lowestDay (the position in the array). I want to print the index and the value at that spot in my main method. I have been searching and I dont know a simple way to do this. Right now I have been just been printing the data from the methods without returning the values. That works but I want to know how to print the values from the main. So once again all I am wondering is how to print both the lowestTemp and the lowestDay from the method in the main.
Here is my code I have:
public static int FindLowestTempInArray(int[] T)
{
// Returns the index of the lowest temperature in array T
int lowestTemp = Uninitialized;
int lowestDay = 0;
for(int day = 0; day < T.length; day++)
{
if(T[day] != Uninitialized && ( T[day] < lowestTemp || lowestTemp == Uninitialized))
{
lowestTemp = T[day];
lowestDay = day;
return lowestTemp;
}
}
return lowestDay;
}
public class Weather {
private static final int Uninitialized = -999;
public static void main(String[] args) {
// TODO Auto-generated method stub
int [] high = new int[32];
int [] low = new int[32];
Init (high);
Init(low);
LoadData(high,low);
Report(high, low);
FindAvg(high);
//FindAvg(low);
//why do i not need to do both the one above and FindAvg(low);
System.out.println("The average for the high is: " + FindAvg(high));
System.out.println("The average for the low is: " + FindAvg(low));
//Lowest(high, low);
FindLowestTempInArray(high);
System.out.println(FindLowestTempInArray(high) + "\n" + FindLowestTempInArray(low));
Highest(high,low);
System.out.println("\n" + "The highest high is: " + Highest(high, low) + " degrees." + "\n" +
"This temperature was recorded on day: " + Highest(high, low));
System.out.println("\n" + "The highest low is: " + Highest(low, high) + " degrees." + "\n" +
"This temperature was recorded on day: " + Highest(low, high));
// LeastToGreatest(high, low);
}

There are 2 ways:
Change the return type of your FindLowestTempInArray to int[] i.e integer array and say int[0] islowest temperature and int[1] is lowest day
you can create a new class say Temperature with 2 class variables say temperature and day, and in your method FindLowestTempInArray you can have return type of Temperature and you can set the Temperature object in that method.
Below is sample of return type int[].
public class Weather {
private static final int Uninitialized = -999;
public static void main(String[] args) {
int[] low = new int[args.length];
for (int i = 0; i < args.length; i++) {
System.out.print(args[i] + " ");
low[i] = Integer.parseInt(args[i]);
}
System.out.println("\n");
int[] lowest = new int[2];
lowest = FindLowestTempInArray(low);
System.out.println(lowest[0] + " " + lowest[1]);
}
public static int[] FindLowestTempInArray(int[] T) {
int[] lowest = new int[2];
lowest[0] = Uninitialized;
lowest[1] = 0;
for (int day = 0; day < T.length; day++) {
if (T[day] != Uninitialized
&& (T[day] < lowest[0] || lowest[0] == Uninitialized)) {
lowest[0] = T[day];
lowest[1] = day;
}
}
return lowest;
}
}
Solution 2(Inner Class):
public class Weather {
private static final int Uninitialized = -999;
public static void main(String[] args) {
int[] low = new int[args.length];
for (int i = 0; i < args.length; i++) {
System.out.print(args[i] + " ");
low[i] = Integer.parseInt(args[i]);
}
System.out.println("\n");
Weather.Temperature temp = FindLowestTempInArray(low);
System.out.println(temp.temperature + " " + temp.day);
}
public static Weather.Temperature FindLowestTempInArray(int[] T) {
Weather.Temperature temp=new Weather.Temperature();
temp.temperature = Uninitialized;
temp.day = 0;
for (int day = 0; day < T.length; day++) {
if (T[day] != Uninitialized
&& (T[day] < temp.temperature || temp.temperature == Uninitialized)) {
temp.temperature = T[day];
temp.day = day;
}
}
return temp;
}
static class Temperature{
private int temperature;
private int day;
public int getTemperature() {
return temperature;
}
public void setTemperature(int temperature) {
this.temperature = temperature;
}
public int getDay() {
return day;
}
public void setDay(int day) {
this.day = day;
}
}
}

One way would be to change the return type of public static int FindLowestTempInArray(int[] T) to int[], so that you can return both values. Otherwise, as soon as one return statement is executed, the method is exited.
You can use lowest[0] for the day and lowest[1] for the temp, or vice versa.
Another way is to get these two values separately (using parameters to distinguish which return value you want) and store them in two variables. The idea is to get these values stored somewhere in the main method to be able to play with them.
After you do that, you can use System.out to display the values, as desired.

Printing out most expensive boat and it's information from an array

I am working on a boat program that has a super class (Boat) and two subclasses (SailBoat, Powerboat) and I must print out all of the boats information and price as well as the most expensive boat and it's information alone. This is the part I am having trouble with since I am not entirely sure how to go about it. Here is what I have so far...
Boat Class:
public class Boat {
String color;
int length;
public Boat() {
color = "white";
length = 20;
}
public Boat(String col, int leng) {
color = col;
length = leng;
}
public boolean setColor(String col) {
if ("white".equals(col) || "red".equals(col) || "blue".equals(col) || "yellow".equals(col)) {
col = color;
return true;
} else {
System.out.println("Error: can only be white, red, blue or yellow");
return false;
}
}
public String getColor() {
return color;
}
public boolean setLength(int leng) {
if (leng < 20 || leng > 50) {
leng = length;
System.out.println("Sail Boats can only be between 20 and 50 feet, inclusively.");
return false;
} else {
return true;
}
}
public int getLength() {
return length;
}
public String toString() {
String string;
string = String.format("Color = " + color + " Length = " + length);
return string;
}
public int calcPrice() {
int price;
price = 5000 + length;
return price;
}
}
PowerBoat Subclass
import java.text.NumberFormat;
public class PowerBoat extends Boat {
int engineSize;
public PowerBoat() {
super();
engineSize = 5;
}
public PowerBoat(String col, int len, int esize) {
this.color = col;
this.length = len;
engineSize = esize;
}
public boolean setEngineSize(int esize) {
if (esize < 5 || esize > 350) {
System.out.println(
"Error: That engine is too powerful. The engine size must be between 1 and 350, inclusively");
esize = engineSize;
return false;
} else {
return true;
}
}
public int calcPrice() {
int price;
price = 5000 + length * 300 + engineSize * 20;
return price;
}
public String toString() {
NumberFormat nf = NumberFormat.getCurrencyInstance();
nf.setMinimumFractionDigits(2);
nf.setMaximumFractionDigits(2);
return super.toString() + " Engine Size = " + engineSize + " Price = " + nf.format(calcPrice());
}
}
SailBoat subclass
import java.text.NumberFormat;
public class SailBoat extends Boat {
int numSails;
public SailBoat() {
numSails = 0;
}
public SailBoat(String col, int leng, int numsail) {
color = col;
length = leng;
numSails = numsail;
}
public boolean setNumSails(int nsails) {
if (nsails < 1 || nsails > 4) {
nsails = numSails;
return false;
} else {
return true;
}
} // end setNumSails
public int getNumSails() {
return numSails;
}
public int calcPrice() {
int price;
price = length * 1000 + numSails * 2000;
return price;
}
public String toString() {
NumberFormat nf = NumberFormat.getCurrencyInstance();
nf.setMinimumFractionDigits(2);
nf.setMaximumFractionDigits(2);
return super.toString() + "Color: " + color + " Length: " + length + " Number Sails = " + numSails + " Cost = "
+ nf.format(calcPrice());
}
public int getTotalCost() {
int totalCost = 0;
totalCost += calcPrice();
return totalCost;
}
}
Inventory class (tester)
import java.util.ArrayList;
public class Inventory {
public static void main(String[] args) {
// boat objects
Boat pb1 = new PowerBoat("blue", 22, 60);
Boat sb1 = new SailBoat("white", 20, 1);
Boat sb2 = new SailBoat("red", 42, 3);
Boat pb2 = new PowerBoat("yellow", 35, 80);
Boat pb3 = new PowerBoat("red", 50, 120);
Boat sb3 = new SailBoat("blue", 33, 2);
Boat pb4 = new PowerBoat("white", 20, 10);
ArrayList<Boat> AL = new ArrayList<Boat>();
// add boat objects to arraylist
AL.add(pb1);
AL.add(sb1);
AL.add(sb2);
AL.add(pb2);
AL.add(pb3);
AL.add(sb3);
AL.add(pb4);
// print all boat objects
System.out.println("Print all boats");
for (Boat anyBoat : AL) {
System.out.println(anyBoat.toString());
}
int max = 0;
int totalcost = 0;
Boat mostExpensiveBoat = null;
for (Boat anyBoat : AL) {
if (anyBoat instanceof SailBoat) {
totalcost += anyBoat.calcPrice();
if (anyBoat.calcPrice() > max) {
max = anyBoat.calcPrice();
mostExpensiveBoat = anyBoat;
}
}
}
}
}
I am really confused on how to finish up this program, the results I am supposed to get after all the boat information is printed is this..
Total price of all boats is $ 170,500.00
Most Expensive Boat: Color = red Length = 42 Number Sails = 3 Cost = $ 48,000.00
Any help will be greatly appreciated. Thank you.

There are a few design flaws you should correct:
Your Boat class should be an interface or abstract. You can't have a boat that isn't a power boat or sail boat so you should not be able to instantiate one.
Your instance variables should be private.
Make methods abstract that need to be defined by subclasses of Boat (e.g. calcPrice).
If you are able to use Java 8 then there's a nice way of getting the most expensive boat. The following code will print the most expensive boat (using Boat.toString) if one is present.
allBoats.stream()
.max(Comparator.comparingInt(Boat::calcPrince))
.ifPresent(System.out::println);
That avoids having to write the code that manually iterates through your list comparing prices. It also copes with the situation of an empty list (which means there is no maximum). Otherwise you need to initialise to null and compare to null before printing.

Your for loop should look like this:
for (Boat anyBoat : AL) {
totalcost += anyBoat.calcPrice();
if (anyBoat.calcPrice() > max) {
max = anyBoat.calcPrice();
mostExpensiveBoat = anyBoat;
}
}
It doesn't matter if it's a sailBoat or not, you just wanna print the information of the most expensive one, so you can remove the instanceof condition. After that:
NumberFormat nf = NumberFormat.getCurrencyInstance();
nf.setMinimumFractionDigits(2);
nf.setMaximumFractionDigits(2);
System.out.println("Total price of all boats is " + nf.format(totalcost));
System.out.println("Most expensive boat: " + mostExpensiveBoat.toString());
Should work, since you have already overriden the toString() methods.
one more thing: In your SailBoat toString() method, you are doing:
return super.toString() + "Color: " + color + " Length: " + length + " Number Sails = " + numSails + " Cost = "
+ nf.format(calcPrice());
When you call the super.toString() you are printing the color and the length twice; just call
return super.toString() + " Number Sails = " + numSails + " Cost = " + nf.format(calcPrice());

Methods to display different table content, repeating header issue

I need to be able to use different methods in order to print out certain table content such as a sum, multiplication, or random table to name a few. I cannot figure out how to print out this content separate from the row ID. another problem I am having is when I enter "f" to reprint the table the header gets repeated each time I print it which just creates a very long repeating header after a few reprints, could someone help with this?
The original code will be followed by the IntTable class, it is not completely filled out which I am aware of but I want to figure this out before I move on.
import java.util.Scanner;
public class Assignment6{
public static String returnMenu(){
String menu = "Command Options---------------\na: Create a new table\nb: Change the row sizes\nc: Change the column sizes\nd: Change the data types\ne: Chnge the formats\nf: Display the table\ng: Display the log data\n:?: Display this menu\nq: Quit the program\n------------------------------";
return menu;
}
public static void main(String[] arg){
Scanner scan = new Scanner(System.in);
String input = "p";
String output = "NOOOOO!";
IntTable myTable = new IntTable();
while (!input.equals("q")){
System.out.println("Please input a command: ");
input = scan.nextLine();
if (input.equals("a")){
System.out.print("a [Input three integers to initialize table]: ");
myTable.setRow(scan.nextInt()); myTable.setColumn(scan.nextInt()); myTable.setType(scan.nextInt());
scan.nextLine();
myTable.printTable();
}
else if (input.equals("b")){
System.out.print("b [Enter integer to update table row]: ");
myTable.setRow(scan.nextInt());
scan.nextLine();
}
else if (input.equals("c")){
System.out.println("c [Enter integer to update column]: ");
myTable.setColumn(scan.nextInt());
scan.nextLine();
}
else if (input.equals("d")){
System.out.println("d [Enter integer to update data type]: ");
myTable.setType(scan.nextInt());
scan.nextLine();
}
else if (input.equals("e")){
System.out.println("e [Enter integer to update printf format]: ");
}
else if (input.equals("f")){
System.out.println("f [Display table]: ");
myTable.printTable();
}
else if (input.equals("g")){
System.out.println("g [Display data log]: ");
}
else if (input.equals("?")){
System.out.println(Assignment6.returnMenu());
}
else
System.out.println("Invalid: ***Type \"?\" to get the commands***");
}
}
}
public class IntTable{
private int row, column, type;
static String log, tFormat;
final int TYPE_DEFAULT = 0;
final int TYPE_NUMBERS = 1;
final int TYPE_SUM = 2;
final int TYPE_MULTIPLY = 3;
final int TYPE_RANDOM = 4;
final int TYPE_POWER = 5;
final int TYPE_FIBONACCI = 6;
String beginRow = " * |";
String divider = "-------";
int count = 1;
public IntTable(){
}
public IntTable(int row, int column, int type){
}
public int getRow(){
return row;
}
public int getColumn(){
return column;
}
public int getType(){
return type;
}
public void setRow(int newRow){
row = newRow;
}
public void setColumn(int newColumn){
column = newColumn;
}
public void setType(int newType){
type = newType;
}
public void printTable(){
int count = 1;
printTableHeader();
for(int i = 1; i <row+1; i++){
System.out.printf("%4d %4s", i, " |");
for (int j = 1; j < column+1; j++)
{
System.out.printf("%4d", count);
count++;
}
System.out.println();
}
}
private void printTableHeader(){
for(int i = 1; i < column + 1; i++)
{
beginRow+=" "+i;
divider+="-----";
}
System.out.println(beginRow);
System.out.println(divider);
}
private void printTableRowID(int ID){
ID = row;
for(int i = 1; i <ID+1; i++){
System.out.printf("%4d %4s", i, " |");
System.out.print(getElement(i, (row-(row-1))));
System.out.println();
}
}
private int getElement(int c, int r){
if(type == 0)
return 0;
else if(type == 1)
return c+column;
else if(type == 2)
return c+ r;
else if(type == 3)
return c*r;
else if(type == 4)
return (int)(1 + Math.random()*10);
else if(type == 5)
return (int)Math.pow(r, c);
else
return r;
}
private int pow(int one, int two){
return (int)Math.pow(one, two);
}
private int fibonacci(int fib){
return fib;
}
private int sum(int add, int addd){
return add + addd;
}
private int multiply(int prod, int product){
return prod * product;
}
private int random(int what, int huh){
return (int)(what + Math.random()*huh);
}
}

the reason why header repeating is because you do not reinitialize variable(beginRow and divider)
when you call printTable Method, variable String beginRow = " * |"; String divider = "-------"; is redefined
you need to reintialize variable(beginRow, divider)
look fllowing code which i modified
private void printTableHeader()
{
for(int i = 1; i < column + 1; i++)
{
beginRow+=" "+i;
divider+="-----";
}
System.out.println(beginRow);
System.out.println(divider);
beginRow = " * |";
divider = "-------";
}

How do I check if a class' return of a method equals null?

In my program, I have a while loop that will display a list of shops and asks for an input, which corresponds with the shop ID. If the user enters an integer outside the array of shops, created with a Shop class, it will exit the loop and continue. Inside this loop is another while loop which calls the sellItem method of my Shop class below:
public Item sellItem()
{
displayItems();
int indexID = Shop.getInput();
if (indexID <= -1 || indexID >= wares.length)
{
System.out.println("Null"); // Testing purposes
return null;
}
else
{
return wares[indexID];
}
}
private void displayItems()
{
System.out.println("Name\t\t\t\tWeight\t\t\t\tPrice");
System.out.println("0. Return to Shops");
for(int i = 0; i < wares.length; i++)
{
System.out.print(i + 1 + ". ");
System.out.println(wares[i].getName() + "\t\t\t\t" + wares[i].getWeight() + "\t\t\t\t" + wares[i].getPrice());
}
}
private static int getInput()
{
Scanner scanInput = new Scanner(System.in);
int itemID = scanInput.nextInt();
int indexID = itemID - 1;
return indexID;
}
The while loop in my main class method is as follows:
boolean exitAllShops = true;
while(exitAllShops)
{
System.out.println("Where would you like to go?\nEnter the number which corresponds with the shop.\n1. Pete's Produce\n2. Moore's Meats\n3. Howards Hunting\n4. Foster's Farming\n5. Leighton's Liquor\n6. Carter's Clothing\n7. Hill's Household Products\n8. Lewis' Livery, Animals, and Wagon supplies\n9. Dr. Miller's Medicine\n10. Leave Shops (YOU WILL NOT BE ABLE TO RETURN)");
int shopInput = scan.nextInt();
if(shopInput >= 1 && shopInput <= allShops.length)
{
boolean leaveShop = true;
while(leaveShop)
{
allShops[shopInput - 1].sellItem();
if(allShops == null)
{
System.out.println("still null"); // Testing purposes
leaveShop = false;
}
}
}
else
{
System.out.println("Are you sure you want to leave?\n1. Yes\n2. No");
int confirm = scan.nextInt();
if(confirm == 1)
{
exitAllShops = false;
}
}
The problem is here:
boolean leaveShop = true;
while(leaveShop)
{
allShops[shopInput - 1].sellItem();
if(allShops == null)
{
System.out.println("still null"); // Testing purposes
leaveShop = false;
}
}
No matter what I do, I can't get "still null" to print to confirm that I'm correctly calling the return statement of the method sellItem of the class Shop. What am I doing wrong?

After calling allShops[...].sellItem(), allShops is still a valid array reference -- there's no way it could be null! You probably want to test the return value from sellItem:
if(allShops[shopInput-1].sellItem() == null)