Java if statment doesnt seem to be working corrently
hi all i have written a if else statement, it all compiles with no issues and the program runs with no issues at all, but it doesnt matter what i enter it will go to the last else statment even if it matchs the statment
i have added the code if u could please help
i have added the code if u could please help
import java.util.Scanner;
import java.text.DecimalFormat;
public class Point
{
public static void main (String [] args)
{
Double x = 0.0; // This will store the value for the x Plane
Double y = 0.0; // This will store the value for the y plane
String direction; // This will store the keyboard input from the user input
//This will creat the scanner object to read from the keyboard
Scanner Keyboard = new Scanner (System.in);
//This will create formattion for the output of x and y
DecimalFormat formatter = new DecimalFormat ("#0");
System.out.println ("This program updates position of a traveling point in a square");
do
{
System.out.println ("Starting position of the point is " + "(" +(formatter.format(x)) + "," +(formatter.format(y)) + ")" );
System.out.print ("Enter a direction for the point to move (u, d, l or r):");
direction = Keyboard.nextLine();
if (direction == "r" || direction == "R")
{
x = (x + 1);
}
else if (direction == "l" || direction == "L")
{
x = (x - 1);
}
else if (direction == "u" || direction == "U")
{
y = (y + 1);
}
else if (direction == "d" || direction == "D")
{
y = (y - 1);
}
else
{
System.out.println("Invalid entry, try again");
}
} while (direction != "q");
}
}
Example:
direction.equals("r)
String vaues should be compared using equals()
i forgot a -> "
as you are comparing for both upper and lower case you can do it in one of the following ways..
if(direction.equalsIgnoreCase("r")){
//do something..
}else if(...
or
if(direction.toLoweCase().equals("r")){
...
}else if(...
direction .equalsIgnoreCase(r)------
this is a good explanation of == vs equals and also explains why in some cases == can happen to be
true:
http://stackoverflow.com/questions/767372/java-string-equals-versus
ASKER
ok got it working but my while loop doesnt seem to work how do i get that partworking now
Did you change to
while (!direction.equals("q"))
In that part?
while (!direction.equals("q"))
In that part?
ASKER
ok i need it to work like this how do i do that
}while (x != 4 || x != -4 || y !=4 || y !=-4);
}while (x != 4 || x != -4 || y !=4 || y !=-4);
could it be that you want frequently to ask which key a user pressed?
because if you want to something like that you did it the wrong way...
you have to use a so called keylistener which is automatically activated.
what you are doing is polling until the user has pressed a key...
because if you want to something like that you did it the wrong way...
you have to use a so called keylistener which is automatically activated.
what you are doing is polling until the user has pressed a key...
ASKER
narr not after that i just want to know when x = 4 or - 4 or y = 4 or - 4 and when the while loop
so you want to go out of the loop when at least one of these
conditions is true? Say, you want to finish is x is equal to 4 or when
x is equal to -4, etc.
then you probably what to have AND's rather than OR's
So you should sit in the loop
if all these conditions are true simultaneously that x != 4 and x != -4 and y != 4 and y != -4
so it should be
while (x != 4 && x != -4 && y !=4 && y !=-4);
the way you wrote it
(x != 4 || x != -4 || y !=4 || y !=-4) this would be always true as x cannot be simultaneously 4 and -4
conditions is true? Say, you want to finish is x is equal to 4 or when
x is equal to -4, etc.
then you probably what to have AND's rather than OR's
So you should sit in the loop
if all these conditions are true simultaneously that x != 4 and x != -4 and y != 4 and y != -4
so it should be
while (x != 4 && x != -4 && y !=4 && y !=-4);
the way you wrote it
(x != 4 || x != -4 || y !=4 || y !=-4) this would be always true as x cannot be simultaneously 4 and -4
ASKER
ok mate that seemed to work but i need thsi message to print on the screen
else if (y == 4 || y == -4)
{
System.out.println("The point reached the boundary at" + "(" +(formatter.format (x)) + "," + (formatter.format(y)) + ")" + " after " + (formatter.format (count)) + " moves." );
}
before it exits
else if (y == 4 || y == -4)
{
System.out.println("The point reached the boundary at" + "(" +(formatter.format (x)) + "," + (formatter.format(y)) + ")" + " after " + (formatter.format (count)) + " moves." );
}
before it exits
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otherwise you comparing the references....