The project I am working on requires a bank account balance to be printed using a toString method. I am not allowed to add any methods to my current program, but I need to format my myBalance variable to a double that goes to two decimal places instead of one. In this particular instance my program should be printing 8.03, but it is printing 8.0.
Here is my toString method:
public String toString()
{
return"SavingsAccount[owner: " + myName +
", balance: " + myBalance +
", interest rate: " + myInterestRate +
",\n number of withdrawals this month: " + myMonthlyWithdrawCount +
", service charges for this month: " +
myMonthlyServiceCharges + ", myStatusIsActive: " +
myStatusIsActive + "]";
}
I am very new to Java still, so I would like to know if there is a way to implement %.2f into the string somewhere to format only the myBalance variable. Thank you!
Use String.format(...) for this:
#Override
public String toString() {
return "SavingsAccount[owner: " + myName +
", balance: " + String.format("%.2f", myBalance) +
", interest rate: " + String.format("%.2f", myInterestRate) +
",\n number of withdrawals this month: " + myMonthlyWithdrawCount +
", service charges for this month: " +
myMonthlyServiceCharges + ", myStatusIsActive: " +
myStatusIsActive + "]";
}
or more succinctly:
#Override
public String toString() {
String result = String.format("[owner: %s, balance: %.2f, interest rate: %.2f%n" +
"number of withdrawals this month: %d, service charges for this month: %.2f, " +
"myStatusIsActive: %s]",
myName, myBalance, myInterestRate, myMonthlyWithdrawCount,
myMonthlyServiceCharges, myStatusIsActive);
return result;
}
Note that khelwood asked about my use of "%n" for a new-line token rather than the usual "\n" String. I use %n because this will allow the java.util.Formatter to get a platform specific new-line, useful in particular if I want to write the String to a file. Note that String.format(...) as well as System.out.printf(...) and similar methods use java.util.Formatter in the background so this applies to them as well.
Use String.format()
Example :
Double value = 8.030989;
System.out.println(String.format("%.2f", value));
Output :
8.03
Related
Im having trouble to find a way for formatting this:
System.out.println("Product price reported as $" + price + " before tax and $" + result + " after " + this.tax + " % tax"):
Im trying like this.
String formatDecimals = String.format("%.2f","Product price reported as $" + price + " before tax and $" + result + " after " + this.tax + " % tax"):
I want to have two decimals. Any help
You are trying to format a string as a float, this will not work. The whole text has to go into the "format" parameter:
String formatDecimals = String.format("Product price reported as $%.2f before tax and $%.2f after %.2f %% tax", price, result, this.tax);
I know that I can just use printf to format it but printf is used to print. I want to use the formatting to store the data then call the data to print it outside the do while loop.
#Override
public String toString() {
Scanner input = new Scanner(System.in);
String enter = "", data = "";
double totalCommission = 0.0;
DecimalFormat df = new DecimalFormat();
do {
setTransaction();
setSalesNum();
setName();
setAmount();
setCommission();
setRate();
do {
//prompt user to enter another
System.out.println("Would you like to enter another? [Y/N]");
boolean error = false;
//error prompt if y or n is not entered
enter = input.next();
if (!(enter.equals("n") || enter.equals("N") || enter.equals("y") || enter.equals("Y"))) {
error = true;
System.out.println("Invalid input! Please enter again.\n Would you like to enter another student's mark? [Y/N]");
} else {
error = false;
}
} while (false);
//setting the decimal places
df.setMaximumFractionDigits(2);
df.setMinimumFractionDigits(2);
//transaction details saved here
data += getTransaction() + "\t" + getSalesNum() + "\t\t" + getName() + "\t\t" + (df.format(getAmount())) + "\t" + " " + getRate() + "%" + "\t\t" + (df.format(getCompute())) + "\n";
totalCommission = totalCommission + getCompute();
} while (enter.equalsIgnoreCase("Y"));
System.out.println("Sales\tCommission");
System.out.println("TNO#\tSALESNO#\tNAME\t\tAMOUNT\t\t" + " " + "COMM RATE\tCOMMISSION");
return String.format(data + "\t\t\t\t\t\t" + " " + "TOTAL COMMISSION\t" + (df.format(totalCommission)));
}
So what I wanted to do is for this part data += getTransaction() + "\t" + getSalesNum() + "\t\t" + getName() + "\t\t" + (df.format(getAmount())) + "\t" + " " + getRate() + "%" + "\t\t" + (df.format(getCompute())) + "\n"; to be formatted inside while (enter.equalsIgnoreCase("Y")); then send data here: return String.format(data + "\t\t\t\t\t\t" + " " + "TOTAL COMMISSION\t" + (df.format(totalCommission)));
I'm sorry but I don't understand what you want to achieve. You may add an input and desired output example.
First of all:
if (!(enter.equals("n") || enter.equals("N") || enter.equals("y") || enter.equals("Y"))) {
if (!(enter.equalsIgnoreCase("n")|| enter.equalsIgnoreCase("y"))) {
You talked about print so you may want to take a look into: https://www.javatpoint.com/java-string-format
Because you mentioned String.format already I guess I misunderstood your question. If you reply back to me I will try to help you.
You wrote that you want to store your data inside that while loop and return it later. In this case, I would add every data to a list and return this list.
I'm trying to find out why the %.2f declaration when outputting a decimal isn't working in my code, I've checked other similar questions but I can't seem to locate the issue in the specific logic error I'm receiving. When I go to compile my program it compiles fine, I go to run it and everything outputs fine until I get to the final cost where I'm trying to only display that decimal value with 2 decimal places.
I get an exception in thread "main"
Java.util.illegalformatconversionexception f! = Java.lang.string
At java.util.Formatter$formatspecifier.failconversion(Unknown Source)
At java.util.Formatter$formatspecifier.printFloat(Unknown Source)
At java.util.Formatter.format(Unknown Source)
At java.io.printstream.format(Unknown Source)
At java.io.printstream.printf(Unknown Source)
At Cars.main(Cars.java:27)
Here is my code:
import java.util.Scanner;
public class Cars
{
public static void main(String [] args)
{
Scanner input = new Scanner(System.in);
int carYear, currentYear, carAge;
double costOfCar, salesTaxRate;
double totalCost;
String carModel;
System.out.println("Please enter your favorite car model.");
carModel = input.nextLine();
System.out.println("Please enter the year of the car");
carYear = input.nextInt();
System.out.println("Please enter the current year.");
currentYear = input.nextInt();
carAge = currentYear - carYear;
System.out.println("How much does the car cost?");
costOfCar = input.nextDouble();
System.out.println("What is the sales tax rate?");
salesTaxRate = input.nextDouble();
totalCost = (costOfCar + (costOfCar * salesTaxRate));
System.out.printf("The model of your favorite car is" + carModel + ", the car is" + " " + carAge + " " + " years old, the total of the car is" + " " + "%.2f",totalCost + " " + " dollars.");
}
}
I'm not exactly sure what's causing the issue.
Try:
System.out.printf("The model of your favorite car is %s, the car is %d years old, the total of the car is %.2f dollars.", carModel, carAge, totalCost);
Or the more readable:
System.out.printf("The model of your favorite car is %s," +
" the car is %d years old," +
" the total of the car is %.2f dollars.",
carModel, carAge, totalCost);
It's because %.2f is replaced with the entire second argument in that method call. The problem is that by specifying f in %.2f, you are saying that the second argument is a float or double. The second argument in this case is totalCost + " " + " dollars." which evaluates to a string.
To fix this problem, you need to make the second argument be a float or double. This can be achieved by moving + " " + " dollars." from the end of the second argument to the end of the first argument, like so:
System.out.printf("The model of your favorite car is" + carModel + ", the car is" + " " + carAge + " " + " years old, the total of the car is" + " " + "%.2f" + " " + " dollars.",totalCost);
You can also remove many of the unnecessary concatenations from that line, resulting in this:
System.out.printf("The model of your favorite car is" + carModel + ", the car is " + carAge + " years old, the total of the car is %.2f dollars.", totalCost);
The variable has to go as a parameter to the System.out.printf() function. The "%.2f" will be replaced by the double value that is passed as the second parameter.
For Example:
System.out.printf("The value is %.2f", value);
The same thing is true for other variable types and for multiple variables,
String str = "The value is: ";
double value = .568;
System.out.printf("%s %.2f", str, value);
This will output: "The value is: .57"
I'm coding a simulation of a sports game, and it works fine for the most part; compiles and runs like it should. The directions ask that I I assume that I am supposed to be using printf and %.2f, but whenever I try to incorporate that into my code, it ceases to run properly. Help would be much appreciated!
import java.util.Scanner;
public class Team {
public String name;
public String location;
public double offense;
public double defense;
public Team winner;
public Team(String name, String location) {
this.name = name;
this.location = location;
this.offense = luck();
this.defense = luck();
}
public double luck() {
return Math.random();
}
Team play(Team visitor) {
Team winner;
double home;
double away;
home = (this.offense + this.defense + 0.2) * this.luck();
away = (visitor.offense + visitor.defense) * visitor.luck();
if (home > away)
winner = this;
else if (home < away)
winner = visitor;
else
winner = this;
return winner;
}
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
System.out.println("Enter name and location for home team (on separate lines)");
String homeName = s.next();
String homeLocation = s.next();
Team homeTeam = new Team(homeName, homeLocation);
System.out.println("Enter name and location for home team (on separate lines)");
String awayName = s.next();
String awayLocation = s.next();
Team awayTeam = new Team(awayName, awayLocation);
Team winnerTeam = homeTeam.play(awayTeam);
System.out.printf("Home team is:" + homeName + " from" + homeLocation + " rated" + homeTeam.offense + " (offense) +" + homeTeam.defense + " (defense)" + "\n");
System.out.printf("Away team is:" + awayName + " from" + awayLocation + " rated" + awayTeam.offense + " (offense) +" + awayTeam.defense + " (defense)" + "\n");
System.out.printf("Winner is:" + winnerTeam.name + " from" + winnerTeam.location + " rated" + winnerTeam.offense + " (offense) +" + winnerTeam.defense + " (defense)" + "\n");
}
You have misunderstood the printf method. You do not concatenate strings the way you do in this line and its successors (reformatted for width reasons):
System.out.printf("Home team is:" + homeName +
" from" + homeLocation +
" rated" + homeTeam.offense +
" (offense) +" + homeTeam.defense +
" (defense)" + "\n");
This is like the way an old coworker tried to use PreparedStatements to prevent SQL injection attacks, but constructed the query string by concatenation anyway, making the attempt ineffective. Instead, look at the signature of printf:
public PrintWriter format(String format, Object... args)
The first argument is a format string, which contains static text and format directives beginning with %. In typical use, each format directive corresponds to one argument of the method. Replace the interpolated variables with directives.
Strings are usually formatted with %s: s for string. Doubles are usually formatted with %f: f for float (or double). Characters between the % and the letter are options. So, let's replace the strings you interpolated with directives:
"Home team is: " + "%s" + // Inserted a space.
" from" + "%s" +
" rated" + "%6.2f" + // Six characters, 2 after the decimal.
" (offense) +" + "%6.2f" +
" (defense)" + "%n" // %n means the appropriate way to get a new line
// for the encoding.
Now we put it all together:
System.out.format("Home team is: %s from %s rated %6.2f (offense) + %6.2f (defense)%n",
homeName, homeLocation, homeTeam.offense, homeTeam.defense);
This is a lot simpler. Additionally, another reason to avoid interpolating strings in a format string is that the strings you interpolate may contain a percent sign itself. See what happens if you unguardedly write this:
String salesTax = "5%";
System.out.format("The sales tax is " + salesTax);
That's equivalent to
System.out.format("The sales tax is 5%");
Unfortunately, the percent sign is treated as a format directive, and the format statement throws an exception. Correct is either:
System.out.format("The sales tax is 5%%");
or
String salesTax = "5%";
System.out.format("The sales tax is %s", salesTax);
But now I should ask why you did not take homeName and homeLocation from Team. Certainly they are more relevant to Team than to each other. In fact, you should look up the Formattable interface, and with proper coding you can write:
System.out.format("%s%, homeTeam);
Try this:
public class A {
public static void main(String[] args) {
System.out.println(String.format("%.2f", 12.34123123));
}
}
I dont get why when i compile this code i get the incorrect zip code.
John Smith
486 test St.
Yahoo, MA 898 - 2597JohnSmith
486 test St.
Yahoo, MA 898 2597
Code
public class test
{
public static void main(String[] args) {
String firstName = "John";
String lastName = "Smith";
int streetNumber = 486;
String streetName = "test St.";
String city = "Yahoo";
String state = "MA";
int zip = 01602;
int zipplus4 = 2597;
System.out.print(firstName + " " + lastName + "\n" + streetNumber + " " + streetName + "\n" + city + ", " + state + " " + zip + " - " + zipplus4);
System.out.println(firstName + lastName);
System.out.println(streetNumber + " " + streetName);
System.out.println(city + ", " + state + " " + zip + " - " + zipplus4);
}
}
When you specify a number with a leading zero, it gets treated as an Octal (base-8, as opposed to decimal base-10 or hexadecimal base-16).
01602 octal == 898 decimal
Since Java wasn't desgined with Zip codes in mind, to get the desired effect, drop the leading zero, and format it when you print it:
System.out.println(city + ", " + state + " " + new java.text.NumberFormat("00000").format(zip) + " - " + new java.text.NumberFormat("0000").format(zipplus4));
Make those zip codes String instead of int and it'll be fine.
public class test
{
public static void main(String[] args)
{
String firstName = "John";
String lastName = "Smith";
int streetNumber = 486;
String streetName = "test St.";
String city = "Yahoo";
String state = "MA";
String zip = "01602";
String zipplus4 = "2597";
System.out.print(firstName + " " + lastName + "\n" + streetNumber + " " + streetName + "\n" + city + ", " + state + " " + zip + " - " + zipplus4);
System.out.println(firstName + lastName);
System.out.println(streetNumber + " " + streetName);
System.out.println(city + ", " + state + " " + zip + " - " + zipplus4);
}
}
Outcome:
John Smith
486 test St.
Yahoo, MA 01602 - 2597JohnSmith
486 test St.
Yahoo, MA 01602 - 2597
Process finished with exit code 0
I'd also advise you to encapsulate those into sensible objects. Why deal with String primitives when you can use an Address class? Java's object-oriented; better to think in terms of objects.
01602 - this 0 at the beginning means you are using octal rather than decimal numbers. Remove it and you'll be fine :-).
BTW IntelliJ IDEA even displays warning here.
You should use String type for zip and zipplus4.
If you cannot change the type then you can use the following in your println statement
String.format("%05d", zip)
Take off the leading zero~ or make it a string
A Zipcode shouldn't be stored in a numeric datatype because it isn't really something you wnat to do math on, instead store it as a String and it'll work fine.