Develop Reference

Exit array for loop Java [duplicate]

This question already has answers here:
How do I compare strings in Java?
(23 answers)
Closed 4 years ago.
Consider my code below:
System.out.println("Insert your inventory");
for (int i = 0; i<20;i++) {
System.out.print(i+1+".");
if (inventory[i] == "N" || inventory[i]=="n") {
break;
}
inventory[i] = s.nextLine();
}
How can I exit from this loop if the user enters 'N' or 'n'?

You're comparing string with == operator. It does not yield correct result because your constant string "N" and your input "N" do not have same reference/pointer.
You have to use equals() to guarantee the correct compare result between strings.
Replace
if (inventory[i] == "N" || inventory[i]=="n")
With
if (inventory[i].equals("N") || inventory[i].equals("n"))

You should compare your String variables with the .equals() method instead of the == operator.
An explanation about why this is important can be found here on StackOverflow.

JOptionPane not reading the string [duplicate]

This question already has answers here:
How do I compare strings in Java?
(23 answers)
Closed 6 years ago.
I am trying to use the value of a String obtained through JOptionPane. However, there is a problem with reading the String. What am I doing wrong here?
import javax.swing.JOptionPane;
public class convertNumber123 {
public static void main(String[] args){
String numsystem1;
numsystem1 = JOptionPane.showInputDialog("Please enter the numeral system that you want to convert from: binary, octal, decimal or hexadecimal.");
if (numsystem1 == "Binary" || numsystem1 == "Octal" || numsystem1 == "Decimal" || numsystem1 == "Hexadecimal")
System.out.println (numsystem1 + "it is!");
else
System.out.println ("Please, enter the correct system name.");
}
}

The way you are comparing strings is wrong. In java you have to use the .equals() method like this
if (numsystem1.equals("Binary") || numsystem1.equals("Octal") || numsystem1.equals("Decimal") || numsystem1.equals("Hexadecimal"))

Apparently, I was using == instead of equals() method. That was the problem.

Comparing user input values [duplicate]

This question already has answers here:
How do I compare strings in Java?
(23 answers)
Closed 7 years ago.
I am not sure why but when I get a string from the user, I cannot compare it in an if statement but when I try to print it, it works fine.
Part of my code:
Scanner in = new Scanner(System.in);
while (true) {
String userInput;
int rowInput, colInput;
printBoard(board);
System.out.print("Move: ");
userInput = in.next();
// shift board right on a row
if (userInput == "r") {
System.out.print("row #: \r");
rowInput = in.nextInt();
moveRight(--rowInput, board);
}
Does anyone know why this isn't working as expected?

You an try this:
if (userInput.equals("r"))
== is used to compare the address and equals is used to compare contents.

I should be using equals instead of ==.
So it would lead to:
...
if (userInput.equals("r"))
...

String comparison doesn't work in while loop [duplicate]

This question already has answers here:
How do I compare strings in Java?
(23 answers)
Closed 8 years ago.
Noob Java question: Why won't this Do While loop accept the user input? When I use a different variation (such as int for the answer), it works. But when I look for a string, it never accepts the string and escapes the loop.
This works:
int value = 0;
do {
System.out.println("Enter a number: ");
value = scanner.nextInt();
}
while(value != 5);
System.out.println("Do while loop has ended.");
This doesn't work:
String pass;
String word = "word";
do {
System.out.println("Enter password: ");
pass = scanner.nextLine();
}
while(pass != word);
System.out.println("Password accepted.");
Thanks

Change this:
while(pass != word);
to this:
while(!pass.equals(word));
You were comparing the references when you used !=, not the actual content of the strings. Since they did not point to the same String, your loop would always exit on the first run.

"==" compares addresses in memory so if you enter the word which will be the same, the reference you have stored will point to different object.

The if statement is not properly executing after user inputs which if-statement they want to input [duplicate]

This question already has answers here:
How do I compare strings in Java?
(23 answers)
String.equals versus == [duplicate]
(20 answers)
Closed 9 years ago.
package temperatureconversion;
import java.util.Scanner;
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
System.out.println("Please enter Conversion type: Press C for Celsius to Fahrenheit or press F For Fahrenheit to Celsius.");
String Vctype = keyboard.next();
if (Vctype == "f" || Vctype == "F"){
System.out.println("Please enter fahrenheit");
double Vfahrenheit = keyboard.nextInt();
Vfahrenheit = (Vfahrenheit)*(9/5)+(32);
System.out.println(Vfahrenheit);
}
if (Vctype == "c" || Vctype == "C"){
System.out.println("Please enter celcius");
double Vcelcius = keyboard.nextInt();
Vcelcius = (Vcelcius - 32)*(5/9);
System.out.println(Vcelcius) ;
}
}
}
Hello guys I was wondering if anyone could help me with the above code. Basically in the output console in netbeans the program just seems to end after I hit C or F, but instead it should ask for a number then allow a number input, then calculate and finally display the calculation. It doesn't seem to be executing the if statements Where am I going wrong?

You are comparing String with ==. So it doesnt work, you have to use this :
if (Vctype.toLowerCase().equals("f"))
Note also, that using a "toLowerCase" makes the whole string lowercase, so you dont have to have two options for "F" and "f".
If you want, you can use "compareTo"
if (Vctype.toLowerCase().compareTo("f") == 0)