I'm having a bit of trouble getting a few parts of my code to work properly.
I'm still a bit new to java and could some direction and clues to where I went wrong.
The error comes from the if statements. I feel like i know why they are erring out because the || are undefined but I'm not sure how to fix it. What I'm trying to get it to do is take the inputs either L,R,F,B (left, right, forward and back). lowercase the input and either accept either one or the other using boolean "or".
import java.util.Scanner;
public class ChooseYourAdventure {
public static void main(String[]args) {
Scanner input = new Scanner(System.in);
System.out.print("Choose a diection: ");
String direction = input.nextLine().toLowerCase();
System.out.printf(" %s and %s/n",getDirection (way),getYourChoice (found));
}
public static String getYourChoice (String found) {
String result = "Unknown";
switch (found)
{
case "l":
result = " now we all know you can turn left unlike Zoolander";
break;
case "left":
result = " now we all know you can turn left unlike Zoolander";
break;
case "r":
result = " you fall down a hole never to be seen again... sad.";
break;
case "right":
result = " you fall down a hole never to be seen again... sad.";
break;
case "f":
result = " YOU ARE THE KWISATZ HADERACH!!";
break;
case "forward":
result = " YOU ARE THE KWISATZ HADERACH!!";
break;
case "b":
result = " you are a scaredy cat but, you live to fight or runaway another day";
break;
case "back":
result = " you are a scaredy cat but, you live to fight or runaway another day";
break;
}
return result;
}
public static String getDirection(String way) {
String result;
if (way == "l" || "left") {
System.out.print("Your character moves left");
}
else if (way == "r" || "right") {
System.out.println("You character moves right");
}
else if (way == "f" || "forward") {
System.out.println("Your character moves forward");
}
else if (way == "b" || "back") {
System.out.println("Your character moves forward");
}
else {
System.out.println(" You cant go that way ");
}
return result;
}
}
All your if statements are wrong. When using || or &&, you need to specify the variable way on each side of the ||:
if (way == "l" || way == "left") {
System.out.print("Your character moves left");
}
Related
I am writing some tests for a Java method which contains a switch statements but it seems that the "default statement" does not work. I only accept: Yes, No, Maybe. Everything else should return Maybe. My test always return the user input, does not matter what the user typed, so I guess my switch statement is not correct.
I have tried to move the default statement on the top
#Override
public String choice(String ans) {
getChoice = ans;
switch (ans) {
case "Yes":
break;
case "No":
break;
default:
getChoice = "Maybe";
}
return getChoice;
}
Thank you!
Your switch should work... As Kyle tells you "what are you overriding ?"
But why a switch when you can perform an "if then else" ?
Public String choice (String choice) {
If (choice.equals("yes") || choice.equals("no") {
return choice;
else {
return "maybe";
}
}
Switch is fine for multiple choices
Is it possible to have a switch-case statement with more than a variable in groovy? I tried with tuples but the case part doesn't accept more than one argument.
I am trying to avoid several nested if statements so instead of
if (a==1) {
if (b==2) {
if (c==3) {
// do something
}
}
}
else {
if (a==4) {
if (b==5) {
if (c==6) {
//do something else
}
}
}
}
Can I do:
switch(a,b,c) {
case : (1,2,3) // if a==1, b==2 and c==3
// do something
...
case : (4,5,6)
// do something else
...
}
}
Groovy is just dirty java, you don't need any class definition. everything you write in a java method you can write it directly in groovy.
switch (num) {
case 1:
case 2:
case 3:
System.out.println("1 through 3");
break;
case 6:
case 7:
case 8:
System.out.println("6 through 8");
break;
}
To answer your question, inside the switch we need an expression, not function parameters.
Based on your edit, I believe that this should work:
if (a == 1 && b == 2 && c == 3) {
// do something
} else if (a == 4 && b == 5 && c == 6) {
// do something else
}
If you want a switch statement instead, that's possible:
def val = [a, b, c]
switch (val) {
case {it == [1, 2, 3]}:
// something
break;
case {it == [4, 5, 6]}:
// something else
break;
class Solution{
static void main (String...args){
BufferedReader br=new BufferedReader(new
InputStreamReader(System.in))
def val=br.readLine()
switch(val){
case('E0'):
println "Basic"
break;
default:
break;
case('E1'):
println "Inter"
break;
case('E2'):
println "Advance"
break;
default:
println "not defined"
}
}
}
My problem is that my switch (case) statement keeps evaluating an extra switch case statement. And I don't understand why it's doing this.
My problem is in case 10:
It's always being evaluated, doesnt matter what case # i choose. It will always run to case 10: and evaluate if it's true or not.
I'v been going over it and I don't understand what's going on. Why would it read case 10.
public boolean checkIfPossible(double x, double a, double y) {
boolean pass;
int value = spinnerA.getSelectedItemPosition();
switch (value) {
case 1:
if (x > a && a == 0) {
etX.setError("Error1 ");
pass = false;
break;
} else if (x == a) {
etX.setError("Error2);
pass = false;
break;
}
case 10:
if (x == y) {
etX.setError("Error3");
pass = false;
break;
}
default:
pass = true;
}
return pass;
}
The solution to your problem is to put a break statement after your if and else statements in your case 1 like this:
case 1:
if (x > a && a == 0) {
etX.setError("Error1 ");
pass = false;
}
else if (x == a) {
etX.setError("Error2);
pass = false;
}
break;
The most likely reason you are having this problem is because the conditions for your if and else-if are both not satisfied. There is no break statement to stop the flow (since the if and else-if blocks are not executed). That's why your code eventually spills over to the next case. Try logging the value of x and a to verify.
I hope this helps.. Merry coding!
I'm doing this for a class, and I'm really not terribly awesome at this as I'm over a decade out of practice. I'm trying to write a program that displays a menu so the user can choose between methods of determining if it's a palindrome.
It then needs to redisplay the menu once it has completed the test. I'm getting a stack overflow error in the isPalindrome method since I combined the 2 classes into one class, which I thought would fix another problem I was having with the output! Any thoughts or directions I can take?
import java.util.Scanner;
public class PalHelper
{
public String pal;
public void MenuList()
{
System.out.println("How would you like to check your phrase?");
System.out.println("1. Check the first letter like it's the last letter - Leave no phrase unturned!");
System.out.println("2. I Prefer my Palindromes have the gentle treatment");
System.out.println("3. We're done here");
System.out.print("Selection: ");
}
public PalHelper()
{
Scanner decision = new Scanner(System.in);
MenuList();
switch (decision.nextInt())
{
//to access the character by character method of determination
case 1:
System.out.print("Enter Phrase to Test, the Hard Way:");
Scanner keyboard1 = new Scanner(System.in); //declares scanner variable for user entry
String UserInput1 = keyboard1.next();//Phrase variable
Boolean test1 = isPalindrome(UserInput1);
if (test1 == true){
System.out.println(UserInput1+" is a palindrome. That doesn't make you smart.");
}
else {
System.out.println(UserInput1+" is a not palindrome. Why don't you think a little harder and try again.");
}
System.out.println("..\n..\n..\n");
keyboard1.close();
new MenuList();
break;
//to access the string buffer method of determination
case 2:
System.out.print("Thank you for choosing the gentle way, please enter your phrase:");
Scanner keyboard2 = new Scanner(System.in); //declares scanner variable for user entry
String UserInput2 = keyboard2.next();
Boolean test2 = isPalindrome2(UserInput2);
if (test2 == true){
System.out.println(UserInput2+" is a palindrome. Congratulations! You are so wonderful!");
}
else {
System.out.println(UserInput2+" is a not palindrome. It's ok, I'm sure you'll get it next time.");
}
System.out.println("..\n..\n..\n");
keyboard2.close();
new MenuList();
break;
//exit menu
case 3:
System.out.println ( "Too bad – I hid a boot!" );
break;
//response to input other than 1,2,3
default:
System.out.println ( "No sir! Away! A papaya war is on." );
System.out.println("..\n..\n..\n");
new MenuList();
break;
}// close switch
}//close pal helper
public void Palindrome(String UserInput) {
}
public boolean isPalindrome(String UserInput) {
pal = UserInput.toUpperCase();
if (pal.length() <= 1) {//one character, automatically a palindrome
return true;
}
char start = pal.charAt(0);
char end = pal.charAt(pal.length()-1);
if (Character.isLetter(start) &&
Character.isLetter(end)) {//check if first and last characters match
if (start != end) {
return false; //if the beginning & ending characters are not the same it's not a palindrome
}
else {
Palindrome subpal = new Palindrome(pal.substring(1,pal.length()-1));
return subpal.isPalindrome(); //check middle dropping start and end letters
}
}
else if (!Character.isLetter(start)) {
Palindrome subpal = new Palindrome(pal.substring(1));
return subpal.isPalindrome(pal); //check if first letter is a letter, drop if not
}
else {
Palindrome subpal = new Palindrome(pal.substring(0,pal.length()-1));
return subpal.isPalindrome(pal); //check if first letter is a letter, drop if not
}
}//close isPalindrome
public boolean isPalindrome2(String UserInput){
pal = UserInput.toUpperCase();
pal = pal.replaceAll("\\W", "");//gets rid of space and punctuation
StringBuffer check = new StringBuffer(pal);//reverses pal string and creates new stringbuffer for check
check.reverse();
if (check.toString().equals(pal)){//checks for equality between pal and it's reverse
return true;
}
else {
return false;
}
}//close isPalindrome2
public static void main (String[]args)
{
new PalHelper();
}//close main
}//close class
Aside from my comment above, there is a problem that I noticed: in some cases, you construct a new Palindrome instance with the substring, but pass the full string while recursing to the isPalindrome() method. This causes the recursion to never terminate (which also makes your code hard to follow).
Your example is missing something, the following line has missing closing brackets:
Palindrome subpal = new Palindrome(pal.substring(1,pal.length()-1);
Your comments dont seem to match the code:
return subpal.isPalindrome(pal); //check if first letter is a letter, drop if not
Try adding Output to the Method isPalindrome() or debug it. You are probably not calling it with the right Strings and end up looping over the same Strings over and over.
public boolean isPalindrome(String UserInput) {
System.out.println(UserInput);
...
Edit: If your code really is exaclty like you posted then vhallac is right, you call isPalindrome() with the full String.
I have a tree structure and I want to find all nodes matching a given criteria. Each time I call the find function, it returns next matching node. Children are searched by recursive function call.
For some reason a key comparison of pointers fails for this implementation. Please see the code below, I have pointed out the failing comparison.
HtmlTag* HtmlContent::FindTag(string tagName, string tagParameterContent)
{
if (tagName.empty() && tagParameterContent.empty())
return NULL;
if (this->startTag == NULL)
return NULL;
this->findContinue = this->FindChildren(this->startTag, &tagName, &tagParameterContent);
return this->findContinue;
}
HtmlTag* HtmlContent::FindChildren(HtmlTag* firstTag, string* tagName, string* tagParameterContent)
{
HtmlTag* currentTag = firstTag;
HtmlTag* childrenFound = NULL;
while (currentTag != NULL)
{
if (!tagName->empty() && *tagName == currentTag->tagName)
{
if (tagParameterContent->empty() || currentTag->tagParameters.find(*tagParameterContent, 0) != -1)
{
if (this->findContinue == NULL)
break; // break now when found
else if (this->findContinue == currentTag) // TODO why this fails?
this->findContinue == NULL; // break on next find
}
}
if (currentTag->pFirstChild != NULL)
{
childrenFound = this->FindChildren(currentTag->pFirstChild, tagName, tagParameterContent);
if (childrenFound != NULL)
{
currentTag = childrenFound;
break;
}
}
currentTag = currentTag->pNextSibling;
}
return currentTag;
}
VC++ compiler accepts this code but for some reason I can't put a breakpoint on this comparison. I guess this is optimized out, but why? Why this comparison fails?
I think that you shoud replace == with = in assignment after comparison. Compiler optimalized this whole section because it doesnt do anything useful.