when i try to print out the result with switch i can't get any result
so i thought to convert char to integer so the switch statement gona work but isn't so any ideas about how to find solution
echar guestGuess = input.next().charAt(0);
int x = (int)guestGuess;
switch(x){
case '1':
System.out.println(answer.isfirstGuessRight(guestGuess) + "\n");
break;
case '2:
'System.out.println("We are kontrol your answer" + answer.issecandGuessRight(guestGuess));
There's not problem in Java to use char for switch.
You don't have to cast to int for that.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Please enter something, and I'll take the first char only");
char c = scan.next().trim().charAt(0);
switch (c) {
case '1':
System.out.println("1 for sure");
break;
case '2':
System.out.println("I think it's 2");
break;
default:
System.out.println("I don't know");
}
}
Related
I am trying to write a program that receives the number of sides from the
user and determines the type of figure using switch structure and a while sentinel-controlled loop, but every time I get an infinite loop. How can that be fixed?
import java.util.Scanner;
public class P1 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Please enter the number of sides:");
int s = input.nextInt();
while ( s!=-1)
{
switch (s)
{
case 1: System.out.println("Line");
break;
case 2:System.out.println("Angle");
break;
case 3:System.out.println("Triangle");
break;
case 4:System.out.println("Quadrilateral");
break;
case 5:System.out.println("Pentagon ");
break;
case 6:System.out.println("Hexagon");
break;
case 7:System.out.println("Heptagon");
break;
case 8:System.out.println("Octagon");
break;
case 9:System.out.println("Nonagon");
break;
case 10:System.out.println("Decagon");
break;
default: System.out.println("Enter a valid value:");
}
}
}
}
The while loop is written to continue as long as s!=-1; so you need to change s so that this expression is no longer true.
This question already has answers here:
Variable might not have been initialized error
(12 answers)
Closed 7 years ago.
To practice using if else, do while, and switch statements, I was making a small text adventure game where a user would be able to input their name, gain a randomly generated profession, and be assigned a randomly generated quest. however, halfway though the second goal, the java development program I was using continually said that one of my variables "might not have been initialized".
This is what i have for the code so far:
============
import java.util.*;
public class Adventure1
{
public static void main(String[] args)
{
//initialize variables
Scanner keyboard = new Scanner(System.in);
Scanner keyboardYN = new Scanner(System.in);
Scanner keyboard2YN = new Scanner(System.in);
String name = "";
char userInput;
char userYN;
char user2YN;
int dieRoll = (int) (Math.random() * 9);
char outputType;
char Mage;
char Soldier;
char Explorer;
char howTo;
//exeternal documation
System.out.println("The First Adventure by K. Konieczny ");
System.out.println();
//player name
do
{
System.out.println();
System.out.print("What is your name: ");
name = keyboard.nextLine();
//prompt
System.out.print("So your name is " + name + "? Are you sure y/n : ");
userYN = keyboardYN.nextLine().charAt(0);
System.out.println();
if(userYN == 'y')
{
System.out.println();
}
else
{
System.out.println("Type in your real name.");
}
}//end do
while(userYN == 'n');
//narration pt. 1
System.out.println("You, " + name +
" have just been named the greatest, uh, what was it again?");
System.out.println();
//specialization
System.out.print("Roll the dice to decide what your profession is? y/n : ");
user2YN = keyboard2YN.nextLine().charAt(0);
if(user2YN == 'y')
{
switch (dieRoll)
{
case '0':
case '1':
case '2': outputType = Mage;
case '3':
case '4':
case '5': outputType = Soldier;
case '6':
case '7':
case '8': outputType = Explorer;
default : outputType = howTo;
}//end switch
System.out.println("Oh right, you are the greatest " + outputType + " in the town.");
}
else
{
System.out.println("I must be thinking of someone else then.");
}
//get quest
System.out.println();
System.out.println("End of program");
}//end main
}//end class
============
The error message i get reads "variable Mage might not have been initialized."
I don't have much coding experience, and was wondering what I did wrong and how I could fix it in future programs.
You have:
char Mage;
// ...
case '2': outputType = Mage;
What is the value of Mage at that point? The compiler is warning you that the variable has not been initialized.
You might want to initialize Mage to some value such as:
char Mage = '0';
Or most likely you want a String representation of Mage:
String outputType;
String mage = "Mage";
String soldier = "Soldier";
String explorer = "Explorer";
// ...
switch (dieRoll) {
case '0':
case '1':
case '2': outputType = mage;
break;
case '3':
case '4':
case '5': outputType = soldier;
break;
case '6':
case '7':
case '8': outputType = explorer;
break;
default : outputType = "Oops";
}
i have a problem i dont know what to put on case section, when ever the user input their grades from 0-100 there are output corresponds to their grades failed,good,verygood,excellent.
import java.util.Scanner;
public class ProgTestI {
public static void main (String args[]){
Scanner pao = new Scanner(System.in);
System.out.print("Grades: ");
String grades = pao.next();
int grado = Integer.parseInt(grades);
switch (grado){
case =<74: /* iwant to put 0 to 74*/
System.out.println("Failed");
case : /* 75-80*/
System.out.println("bellow average");
case : /*81-85*/
System.out.println("average");
case : /*86-90*/
System.out.println("Good");
case : /*91-96*/
System.out.println("VeryGood");
default:
}
}
}
You cannot use switch for ranges, you need to replace this chunk of code with proper if/else blocks.
Switch works only on numeric values, but it works like
if(numericVal == 40)
So writing it for ranges is... waste of code, and not readable.
You need to rewrite it:
if( g <= 74){
...
}else if( g > 74 && g <= 80 ){
...
Your case code is incorrect, you can do as Beri mentioned.
If you want to implement switch statement in your application, then you can do as follows:
public static void main(String[] args) {
Scanner pao = new Scanner(System.in);
System.out.print("Grades: ");
String grades = pao.next();
int grado = Integer.parseInt(grades);
int checkedCase=0;
if(grado<=74){
checkedCase=1;
}
else if(grado>=75&&grado<=80){
checkedCase=2;
}
else if(grado>=81&&grado<=85){
checkedCase=3;
}
else if(grado>=86&&grado<=90){
checkedCase=4;
}
else if(grado>=91&&grado<=96){
checkedCase=5;
}
switch (checkedCase){
case 1: /* iwant to put 0 to 74*/
System.out.println("Failed");
break;
case 2: /* 75-80*/
System.out.println("bellow average");
break;
case 3: /*81-85*/
System.out.println("average");
break;
case 4: /*86-90*/
System.out.println("Good");
break;
case 5: /*91-96*/
System.out.println("VeryGood");
break;
default: System.out.println("Please enter a value in range 0-96");
break;
}
}
New to Java and I'm having troubles with my code, it's a switch statement within a while loop. I like to use letters or "char" instead of numbered cases "int" and I have 'q' to quit. Thanks for your input. This is the main code.
import java.util.Scanner;
import java.util.*;
public class supraCritters {
public static void main(String [] arguments) {
Critter nastybat = new Critter();
nastybat.health = 100;
nastybat.mood = 50;
nastybat.hunger = 25;
System.out.println("Your critter has just been born,");
System.out.println("here are the stats of your critter.");
nastybat.checkStats();
System.out.println("\nPlease choose a letter");
System.out.println("[c]heck stats \n[f]eed \n[p]lay \n[r]ead \n[t]rain");
System.out.println("[q]uit");
Scanner sChoice = new Scanner(System.in);
char choice = ' ';
while (choice != 'q') {
switch (choice) {
case 'c':
nastybat.checkStats();
break;
case 'f':
nastybat.feed();
break;
case 'p':
nastybat.play();
break;
case 'r':
nastybat.read();
break;
case 't':
nastybat.train();
break;
case 'q':
System.out.println("good bye");
break;
default:
System.out.println("invalid entry");
break;
}
choice = sChoice.next().charAt(0);
}
}
}
When I enter corresponding letter the loop doesn't show Input method or repeat and 'q' does nothing. Default displays "invalid entry" before input.
Code edited and still have problems.
The input is taken only once, the first time! Therefore the loop always returns the same result. You should duplicate the getting input code inside the loop!
Scanner sChoice = new Scanner(System.in);
char choice = '';
while (choice != 'q') {
switch (choice) {
case 'c':
nastybat.checkStats();
break;
.
.
.
.
.
choice = sChoice.next().charAt(0);
The first line gets input for the first switch run, and the one inside the loop gets the rest.
UPDATE:
The choice = sChoice.next().charAt(0); should be place at the final of the loop, if not, as #proskor says, when user hits 'q' the program will return an 'invalid entry'.
I finished the code and it seems to work. Testing out the methods the object can use now.
Final
import java.util.Scanner;
import java.util.*;
public class supraCritters {
public static void main(String [] arguments) {
Critter nastybat = new Critter();
nastybat.health = 100;
nastybat.mood = 50;
nastybat.hunger = 25;
System.out.println("Your critter has just been born,");
System.out.println("here are the stats of your critter.");
nastybat.checkStats();
Scanner sChoice = new Scanner(System.in);
char choice = ' ';
while (choice != 'q') {
switch (choice) {
case 'c': case 'C':
nastybat.checkStats();
break;
case 'f': case 'F':
nastybat.feed();
break;
case 'p': case 'P':
nastybat.play();
break;
case 'r': case 'R':
nastybat.read();
break;
case 't': case 'T':
nastybat.train();
break;
case 'q': case 'Q':
System.out.println("good bye");
break;
default:
System.out.println("invalid entry");
break;
}
System.out.println("\nPlease choose a letter");
System.out.println("[c]heck stats \n[f]eed \n[p]lay \n[r]ead \n[t]rain");
System.out.println("[q]uit");
choice = sChoice.next().charAt(0);
}
}
}
I was wondering if anyone can see what is wrong with my code. It works except that the program is not acknowledging my switch statement - I searched lots of questions but as I am a novice I am clearly missing something.
import java.util.Scanner;
class Calmlr1 {
public static void main(String[]args) {
Scanner input = new Scanner(System.in);
String anotherOption = "y", operatorOpt= "a";
int no1=0, no2=0;
double result= 0;
System.out.println ("Welcome to the online calculator! Let's begin...");
while (anotherOption.equalsIgnoreCase ("y")) {
System.out.println ("Please enter your 1st number: ");
no1 = input.nextInt();
System.out.println ("Please confirm your operator:\n1 = +\n2 = - \n3 = *\n4 = /");
operatorOpt = input.next ();
System.out.println ("Please enter your 2nd number: ");
no2 = input.nextInt();
switch(no1) {
case 1:
result=no1+no2;
break;
case 2:
result=no1-no2;
break;
case 3:
result=no1*no2;
break;
case 4:
result=no1/no2;
default:
result = 0 ;
break;
}
System.out.println("Your total calculation is: "+result);
System.out.println("Would you like to do another sum? y/n ");
anotherOption=input.next();
}
}
}
You should be using switch(operatorOpt). Right now you are switching on the first number.
You also need to change:
int operatorOpt= 0;
operatorOpt = input.nextInt();
That is, if you want to keep your switch statement the same. Please also see #Daniel Imms answer for an additional bug fix.
Try adding a break at the end of case 4
case 4:
result=no1/no2;
break;
EDIT J L's answer is the main issue, but this is another problem that will break division.
Your switch should be on the operatorOpt and not on no1.
Also, you're missing a break in the case 4. So, if you want to do a division, you'll get 0 as result.
The input from the user for operatorOpt should be done with input.nextLine(). Or, if you want to keep the same switch statement, with input.nextInt().
It should be like this:
switch(operatorOpt)
{
case "+":
result=no1+no2;
break;
case "-":
result=no1-no2;
break;
case "*":
result=no1*no2;
break;
case "/":
result=no1/no2;
break;
default:
result = 0 ;
break;
}
Your switch statement should be on "operatorOpt" and not on "no1" as you suppose to check the operator and based on that you want to do the calculation. However, you must use JDK1.7 to use String in Switch statement since previous versions of JDK do not support String Switch.
Also, you should use "break" in case 4.
Your switch should be on the operatorOpt and not on no1.
You can use like this
switch(operatorOpt)
{
case "+":
result=no1+no2;
break;
case "-":
result=no1-no2;
break;
case "*":
result=no1*no2;
break;
case "/":
result=no1/no2;
break;
default:
result = 0 ;
break;
}