Background: Beginner in programming, very new to this whole "Java" thing.
I love the help, but I do not want a direct answer, more like a point in the right direction, or any which way where I can learn instead of blindly copy/paste. Instead of "heres the right code" more of "hears how you can get the right code"
Thank you :)
Ok so my question is, what is wrong with the prompt ad the IF/THEN statement. When I run it with the prompt, it says cannot find symbol - method prompt(java.lang.String)
Without the prompt, when I run it, after I input my choice, whether right or wrong, it always returns "Sorry, that is'nt a choice. Choose rock, paper or scissors!" even if it is right!
If you need any more info on my problem, let me know :)
Anyway here is the class:
//Player class
import java.util.Scanner;
import java.lang.String;
public class Player
{
private String name;
private String choice;
public Player(String nm)
{
name = nm;
}
public Player(String nm, String ch)
{
name = nm;
choice = ch;
}
public void setName( String nm)
{
name = nm;
}
public void setChoice( String ch )
{
}
public String getChoice()
{
Scanner scan = new Scanner (System.in);
System.out.println("Choose rock, paper or scissors:");
String player = scan.next(); player.toLowerCase();
if ((player != ("rock"))
|| (player != ("paper"))
|| (player != ("scissors")))
{
System.out.println("Sorry, that is'nt a choice. Choose rock, paper or scissors!");
player = prompt("Choose rock, paper or scissors:");
}
else
{
System.out.println("Good choice!");
}
System.out.println("You chose " + player);
return "";
}
public String getName()
{
Scanner scan = new Scanner (System.in);
System.out.println("Whats your name?");
String name = scan.next();
return "";
}
public String toString()
{
return "";
}
}
And the runner:
public class PlayerRunner
{
public static void main(String[] args)
{
Player s = new Player("Michael Jackson", "rock");
System.out.println(s.getChoice());
System.out.println(s.getName());
//outs rock
//call the getName() method
System.out.println(s); //outs Michael Jackson rock
//set the choice to paper
System.out.println(s); //outs Michael Jackson paper
//instantiate a new Player named jb named Jim Bob that chose scissors
//print out Jim Bob
}
}
The goal of this portion was titled to: "Use the Player.java file to create the player. Complete the Player constructors, set
methods, get methods, and the toString. Use PlayerRunner.java to test your Player class."
Let me know if you see that I did anything else wrong :) Again I'm a beginner, but I'm here to learn, not just paste the right answer and move on.
Thank you!!
How about:
public String getChoice() {
Scanner scan = new Scanner(System.in);
System.out.println("Choose rock, paper or scissors:");
String player = scan.next();
while ((!player.equalsIgnoreCase("rock"))
&& !player.equalsIgnoreCase("paper")
&& !player.equalsIgnoreCase("scissors")) {
System.out.println("Sorry, that is'nt a choice. Choose rock, paper or scissors!");
System.out.println("Choose rock, paper or scissors:");
player = scan.next();
}
System.out.println("Good choice!");
System.out.println("You chose " + player);
return "";
}
When you use the == operator, you're comparing whether or not two objects are the same, or whether two primitive type's values are the same.
Since a string is actually an object in Java,
String a = "string";
String b = "string";
System.out.println(a == b);
will return false, but
String a = "string";
String b = a;
System.out.println(a == b);
will return true.
Instead, if you call the equals method of the String class, you can compare whether or not the two values are the same.
String a = "string";
String b = "string";
System.out.println(a.equals(b));
In your case, player != ("rock") will always evaluate as true, which looks to be causing some problems.
You can read more here: Java String.equals versus ==
Related
So, I want to receive input from the user, check if they used alphabetical values and then check if it is too long. If too long, I want to start again from the top (checking if alphabetical) by calling the method I am in. However, when I start over and I type, say "Danny", this will show:
Output: "Thank you, got Danny"
Output: (length of previous, too long input) + "is too many characters, try to keep it under 30."
So somehow, it keeps the original input (that was alphabetical, but above 30) saved and it doesn't alter it when it starts over. Anyone know what I should do instead?
public static String inputPattern() {
Scanner scanner = new Scanner(System.in);
String player;
int strLength;
System.out.println("Please enter your name:");
while (!scanner.hasNext("[A-Za-z]+")) { //Checks if alphabetical value
System.out.println("Please stick to the alphabet!");
scanner.next();
}
player = scanner.next();
player += scanner.nextLine();
System.out.println("Thank you! Got " + player);
strLength = player.length(); // Saves the length of user-inputted name
while (strLength > 30) { // Checks if not too long
System.out.println(strLength + " is too many characters, please try to keep it under 30");
inputPattern(); // Starts over again if too long
}
return player;
}
I have taken your method and modified it a bit.
It is non recursive solution.
Also in your code scanner resource was not closed at the end.
Iterative Solution
import java.util.Scanner;
public class SO66064473 {
public static void main(String[] args) {
inputPatternIterative();
}
public static String inputPatternIterative() {
Scanner scanner = new Scanner(System.in);
String player = "";
int strLength = Integer.MAX_VALUE;
while (strLength > 30) { // Checks if not too long
System.out.println("Please enter your name:");
while (!scanner.hasNext("[A-Za-z]+")) { //Checks if alphabetical value
System.out.println("Please stick to the alphabet!");
scanner.next();
}
player = scanner.next();
player += scanner.nextLine();
System.out.println("Thank you! Got " + player);
strLength = player.length(); // Saves the length of user-inputted name
if (strLength > 30)
System.out.println(strLength + " is too many characters, please try to keep it under 30");
}
scanner.close(); // Closing scanner resource after use.
return player;
}
}
Output :
Please enter your name:
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
Thank you! Got aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
70 is too many characters, please try to keep it under 30
Please enter your name:
aaaaaaaaaaaaaaaaaaaa12
Please stick to the alphabet!
coifvoifoivmrfvoirvoirovroijfoirjfoijroifjrwofjorwfouwrfoijwrofjworjfoiwrjf
Thank you! Got coifvoifoivmrfvoirvoirovroijfoirjfoijroifjrwofjorwfouwrfoijwrofjworjfoiwrjf
75 is too many characters, please try to keep it under 30
Please enter your name:
Danny
Thank you! Got Danny
EDIT : with the suggestion made by #Dev-vruper here is updated easy recursive code
Recursive Solution
import java.util.Scanner;
public class SO66064473 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
inputPatternRecursive(sc);
sc.close();
}
public static String inputPatternRecursive(Scanner sc) {
System.out.println("Please enter your name:");
String player = sc.nextLine();
if (!player.matches("[A-Za-z]+")) {
System.out.println("Please stick to the alphabet!");
inputPatternRecursive(sc);
} else {
System.out.println("Thank you! Got " + player);
if (player.length() > 30) {
System.out.println(player.length() + " is too many characters, please try to keep it under 30");
inputPatternRecursive(sc);
}
}
return player;
}
}
This should solve your problem in a pretty easy way:
public static String inputPattern(){
Scanner scanner = new Scanner(System.in);
String player = "";
int strLength;
boolean bShowedInstruction = true;
System.out.println("Please enter your name:");
while (true) {
if (!bShowedInstruction)
System.out.println("Please enter your name:");
bShowedInstruction = false;
player = scanner.next();
if (!player.matches("[A-Za-z]+")) {
System.out.println("Please stick to the alphabet!");
}
else if (player.length() > 30) {
System.out.println(player.length() + " is too many characters, please try to keep it under 30!");
}
else
break;
}
System.out.println("Thank you! Got " + player);
return player;
}
There's no need for a recursion. A simple while(true) loop does the trick.
It's a pretty clean solution keeping unnecessary scan-methods out of the game.
This question already has answers here:
How do I compare strings in Java?
(23 answers)
Closed 5 years ago.
I've just started java couple of days ago. Im currently following this 'course' http://programmingbydoing.com . Havent had encountered any problems yet but now im stuck at task 32.
heres my code so far (always getting Squirrel instead of moose as output):
import java.util.Scanner;
public class TwoQuestion32 {
public static void main(String[] args) {
boolean animal, vegetable, mineral, smallerthan;
String whatIsIt, biggerThan;
Scanner keyboard = new Scanner(System.in);
System.out.println("Hello and welcome, i've got 2 questions for you!");
System.out.println("Think of an object and i'll try to guess it");
System.out.println();
System.out.println("Question 1) Is it an animal, vegetable or mineral?");
System.out.print(">");
whatIsIt = keyboard.nextLine();
if (whatIsIt == "animal")
animal = true;
if (whatIsIt == "vegetable")
vegetable = true;
if (whatIsIt == "mineral")
mineral = true;
System.out.println("Question 2) Is it bigger than a breadbox?");
System.out.print(">");
biggerThan = keyboard.nextLine();
if (biggerThan == "yes")
smallerthan = false;
if (biggerThan == "no"){
smallerthan = true;}
System.out.print("My guess is that you are thinking of a ");
if (animal = true){
if (smallerthan = true)
System.out.println("squirrel");
}else {
System.out.println("moose");}
}
}
Thanks in advance! Would also love to hear tips how to put up the code in smarter ways. Be friendly, keep in mind i've just started!
Edit: Okay I took another approach. My first attempt was really strange. Thanks for the help!
Heres the working code:
import java.util.Scanner;
public class Questions32 {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
String whatIsIt, whatIsIt2;
String animal = "animal";
String mineral = "mineral";
String vegetable = "vegetable";
String bigger = "yes";
String smaller = "no";
System.out.println("Hello and welcome, i've got 2 questions for you!");
System.out.println("Think of an object and i'll try to guess it");
System.out.println();
System.out.println("Question 1) Is it an animal, vegetable or mineral?");
System.out.print(">");
whatIsIt = keyboard.nextLine();
System.out.println("Question 2) Is it bigger than a breadbox?");
System.out.print(">");
whatIsIt2 = keyboard.nextLine();
if (whatIsIt.equalsIgnoreCase(animal)){
if (whatIsIt2.equalsIgnoreCase(bigger)){
System.out.println("My guess is that you are thinking of a moose");
}else{ System.out.println("My guess is that you are thinking of a squirrel");
}
}
if (whatIsIt.equalsIgnoreCase(vegetable)){
if (whatIsIt2.equalsIgnoreCase(bigger)){
System.out.println("My guess is that you are thinking of a melon");
}else{ System.out.println("My guess is that you are thinking of a carrot");
}
}
if (whatIsIt.equalsIgnoreCase(mineral)){
if (whatIsIt2.equalsIgnoreCase(bigger)){
System.out.println("My guess is that you are thinking of a Camaro");
}else{ System.out.println("My guess is that you are thinking of a paper clip");
}
}
System.out.println("I would ask you if I'm right, but I dont actually care.");
}
}
in your if-statement you are setting animal to true every time if (animal = true){, instead of checking it (==) .
Also, for Strings you must use .equals() instead of ==.
I wrote a simple if / else that is supposed to print the answer to the if else. but does not respond even with the correct input. I can't see what I'm missing.
import java.util.Scanner;
public class MarriageQuiz{
public static void main(String[] args){
Scanner input = new Scanner(System.in);
String marStat;
System.out.print("Please enter your Marital Status (M or S) >> ");
marStat = input.nextLine();
marStat = marStat.toUppercase();
if(marStat.equals('M')){
System.out.print("You are married");
}
else if(marStat.equals('S')){
System.out.print("You are single");
}
}
}
Your code is comparing a String object against a character literal, which I believe the JVM will box into a Character object. Well, these two objects don't belong to the same class, so "M".equals('M') will return false. To remedy this, use "M".equals("M").
change toUppercase() to toUpperCase() and marStat.equals('M') to marStat.equals("M") also marStat.equals('S') to marStat.equals("S")
import java.util.Scanner;
public class MarriageQuiz {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String marStat = "";
System.out.print("Please enter your Marital Status (M or S) >> ");
marStat = input.nextLine();
marStat = marStat.toUpperCase();
if (marStat.equals("M")) {
System.out.print("You are married");
} else if (marStat.equals("S")) {
System.out.print("You are single");
}
}
}
On the other hand, you can use Character type instead of 'String'. Rather using Character would be more accurate as you are dealing with only one character.
Scanner input = new Scanner(System.in);
Character marStat;
System.out.print("Please enter your Marital Status (M or S) >> ");
marStat = input.next().charAt(0);
marStat = Character.toUpperCase(marStat);
if (marStat.equals('M')) {
System.out.println("You are married");
} else if (marStat.equals('S')) {
System.out.println("You are single");
}
use ""
if(marStat.equals("M")){
System.out.print("You are married");
}
else if(marStat.equals("S")){
System.out.print("You are single");
}
As mentioned in a comment above, you are comparing a String object to an autoboxed Character object. One fix is obviously using double quotes, which Java will autobox to a String object your code will work.
A few tips to save a few lines of code: use String.equalsIgnoreCase() to save a line converting the incoming string to uppercase.
Next, consider using a constant for marital status:
public class MarriageQuiz{
private static final String STATUS_MARRIED = "M";
...
if (marStat.equalsIgnoreCase(STATUS_MARRIED)) {
...
That way you can use STATUS_MARRIED all over your code but can change it from, say, "M" to "Married" easily.
I'm trying to make a BAC (blood alcohol content) calculator that takes inputs from the user and lets them know if they qualify to win... a grand DUI prize! I'm trying to use the Scanner to determine if the person is a male or female and then use an if-then statement down the line based on what the user input...but I don't really know how. It should be a very simple fix, but here's what I have and kinda what I want to do with the if-then statement commented out.
import java.util.*;
public class Proj2_Mazzone
{
public static void main (String[] args)
{
Scanner scan = new Scanner(System.in);
String gender;
int D, W, H, age;
...
System.out.print("Enter M if you're a male, or F if you're a female: ");
gender = scan.nextLine();
/*if(gender = M)
{
System.out.println("You're a man!");
}
else if(gender = F)
{
System.out.println("You're a woman!");
}
*/
When comparing String you use .equals() or .equalsIgnoreCase(). Like,
gender = scan.nextLine();
if (gender.equalsIgnoreCase("m")) {
System.out.println("You're a man!");
} else if (gender.equalsIgnoreCase("f")) {
System.out.println("You're a woman!");
}
But, you could also compare the first character with something like
if (Character.toUpperCase(gender.charAt(0)) == 'M') {
System.out.println("You're a man!");
} else if (Character.toUpperCase(gender.charAt(0)) == 'F') {
System.out.println("You're a woman!");
}
note, that's == (not = which is for assignment).
Use like this:
if(gender.equals("M"))
{
System.out.println("You're a man!");
}
else if(gender.equals("F"))
{
System.out.println("You're a woman!");
}
Note: = is assign operator not conditional operator.
You can see how equal condition is work in java at below link.
http://www.programmerinterview.com/index.php/java-questions/java-whats-the-difference-between-equals-and/
What's the difference between ".equals" and "=="?
So I just started learning Java, its literally like my 1st day and I wanted to try to make a coinflip game. I already know a decent amount of Javascript and so i was trying to apply that knowledge to java. So everything has been working so far except one thing: Prompting a user for a choice. So read online that i have to import a scanner so i did that as you can see from my code. I also tried some code where you can have the user import a string but you can see a bit later in my program i change the variable userChoice into a number. So basically i just need help with this. If there is some way to have a variable type that can store both numbers or strings that would be best. But im tottaly open to other ways of doing this! Thanks in advanced! Here is the code:
package test;
import java.util.Scanner;
public class testclass {
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println("hi");
int bob;
bob = (int) Math.floor(Math.random()*2);
System.out.println(bob);
System.out.println("Enter heads or tails?");
System.out.println("You entered "+ userChoice);
if (bob == 0) {
System.out.println("Computer flipped heads");
}
else {
System.out.println("Computer flipped tails");
}
if(userChoice == "Heads") {
userChoice = 0;
}
else {
userChoice = 1;
}
if (userChoice == bob) {
System.out.println("You win!");
}
else {
System.out.println("Sorry you lost!")
}
}
}
Use a scanner, as you said:
Scanner in = new Scanner(System.in);
Then, prompt the user to enter something in:
String userChoice = in.nextLine();
Also, when you compared strings:
if(userChoice == "Heads") {...
that's bad to do for none-primitive objects. It's best to only use the == to compare values that are ints or enums. If you compare a String like this, it won't work, because it's checking if the objects are the same. Instead, compare like this:
if(userChoice.equals("Heads")) {...
Also, to convert to an int (NOTE: You can't convert one type of object to another that aren't related in any way! You'll have to create a new object if you're wanting to do that), do this:
int myInt = Integer.parseInt(myString); // NOTE: Can throw NumberFormatException if non-number character is found.
So your program should look somewhat like:
package test;
import java.util.Scanner;
public class testclass {
public static void main(String[] args) {
//System.out.println("hi");
Scanner in = new Scanner(System.in);
int bob;
int userChoice;
String input;
bob = (int) Math.floor(Math.random()*2);
System.out.println(bob);
System.out.println("Enter heads or tails?");
input = in.nextLine(); // waits for user to press enter.
System.out.println("You entered "+ input);
if (bob == 0) {
System.out.println("Computer flipped heads");
}
else {
System.out.println("Computer flipped tails");
}
if(input.equals("Heads")) {
userChoice = 0;
}
else {
userChoice = 1;
}
if (userChoice == bob) {
System.out.println("You win!");
}
else {
System.out.println("Sorry you lost!");
}
in.close(); // IMPORTANT to prevent memory leaks
}
}
You've already imported the Scanner class so you can now create a variable of the type Scanner for taking inputs.
Scanner in = new Scanner();
userChoice = in.nextLine();
nextLine() can be used to input a character or a string from the user.
To convert the string into a integer, You can assign the integer value to the string in the following way.
if(userChoice == "Heads") {
userChoice = "" + 0;
}
else {
userChoice = "" + 1;
}
"String" datatype in Java can hold both numbers and strings (as you asked). You can get user input using Scanner utility as below:
Scanner input = new Scanner();
userChoice = input.nextLine(); // if it is a string
//userChoice = input.nextInt(); // if it's integer choice
If your string is an integer then you can also parse it to get its integer value. For parsing:
int value = Integer.parseInt(userChoice);
Also for comparing String values you should use "equals" function rather than "==".
if(userChoice.equals("Heads")){...} //rather than if(userChoice == "Heads"){...}
Having imported java.util.Scanner, to get input from the user as a String, create a Scanner object that parameterizes System.in and assign userChoice the value of nextLine() invoked by the Scanner object:
Scanner input = new Scanner(System.in);
String userChoice = input.nextLine();
A few things about your code. The relational operator, ==, is used for comparing primitive data - not objects. Use string1.equals(string2) to see if two strings are equal.
Also, bob = (int) Math.floor(Math.random()*2); is really bob = (int)(Math.random() * 2);
because casting a double as an integer truncates the double to the highest integer less than or equal to it.
It might help you to get the ideas.
public static void main(String[] args) {
Random rd = new Random();
//Enter 1 0R 0
int bob = rd.nextInt(2);
String userChoice;
Scanner sc = new Scanner(System.in);
System.out.println("Please enter a number");
userChoice = sc.nextLine();
System.out.println("You entered " + userChoice + " and bob is " + bob);
int uc = Integer.parseInt(userChoice);
if (uc == bob) {
System.out.println("Hehe");
} else {
System.out.println("Sorry");
}
}