CODEWITHSUNDEEP
javaif-statement
Georg Scharfenberg
Georg Scharfenberg

Reputation: 35

How to test percentage in an if statement?

How can I test the percentage in an if statement?

For example:

        package Walker;

    public class Walker {
         int tuning = 10;
         int speed = 0;
         int gas = 100;
         int energy = 100;
         int time = 1;
         int strecke = 0;
         boolean test = true;
         boolean beschleunigung = false;

        Walker() {
            tuning = 10;
            gas = 0;
            energy = 100;
        }

             public void setGas(int x) {
                 gas = x;
             }

             public void setSpeed(int x) {
                 tuning = x;
             }

             public void walk() {
                 boolean walking = true;
                 while (walking) {

                     if (speed<10) {
                         beschleunigung = true;
                     }else {
                         beschleunigung = false;
                     }
                     if (beschleunigung==true) {
                         speed +=1+(tuning);
                         energy -=1;
                         }
                     strecke = (speed*time);
                     speed = (strecke/time);
                     gas -= 1;
                     energy -= 1;
                     time +=1; 
                     if (gas<1||energy<1){
                         break;
                     }
                     }
             System.out.println("Distance "+(strecke)+" meter");
             System.out.println("Gas left :"+gas);
             System.out.println("Energy left : "+energy);
              }

    }

The _User is able to change the value "tuning" and "gas"

And thats the part i like to add :

if (strecke==33%) {
system.out.println("Test");
}

Could anyone help me?

Upvotes: 2

Views: 7228

Answers (6)

Joeri Hendrickx
Joeri Hendrickx

Reputation: 17445

You're missing an important piece of input here. 33% of what? Some people here have suggested that it's 33% of one, as in 0.33. That's quite unlikely, since you're doing --gas at the end, so you're probably working with integer numbers.

I deduce you intend to say '33% of the initial volume'. So that would become:

public void walk() {
 boolean walking = true;
 int currentGas = initialGas;
 while (walking) {
 if (currentGas == Math.round((double)initialGas * 0.33)) {
  System.out.println("Walker reached at 33% of Gas "+(output*speed)+" meter");
           }
 if (currentGas <0||energy<0) {
  System.out.println("Run out of Gas or Energy!");
  walking = false;
  break;         
 }
 --currentGas ;
 output +=1; }
 System.out.println("Distance "+(output*speed)+" meter");
}

That should do it.

Upvotes: 2

Jay
Jay

Reputation: 1

You don't need a percentage in this particular case, just use plain a plain int. Initialize gas at 100 and then substract one at each iteration of the loop. Replace the code that says "if(gas==33%)" for "if(gas==33)" and that's it.

Upvotes: 0

Boris Pavlović
Boris Pavlović

Reputation: 64632

Create a helper method

private double percentage(double value)
{
  return 100 * value;
}

and use it to wrap gas:

if (percentage(gas) == 33)
{
...
}

Upvotes: 2

Rune Aamodt
Rune Aamodt

Reputation: 2611

Change this:

if (gas==33%)

to:

if (gas==0.33)

(assuming gas is a float/double)

edit: Why am I getting downvoted? 33% is mathematically equivalent to 0.33.

edit: You might also want to do a ranged check like 

if (gas > 0.325 && gas < 0.335)

Because just checking for the exact value of 33% is probably not what you wanted.

Upvotes: 2

Matt Varblow
Matt Varblow

Reputation: 7901

You're not using % correctly. In Java the % operator is used to find a remainder. For example the following are true:

0 == 6 % 3 (because 6 divided by 3 has no remainder)

1 == 7 % 3 (because 7 divided by 3 has a remainder of 1)

If you want to convert gas to a percentage then you should probably be dividing it by something. For example:

if (gas / fulltank == 0.33)

However, you also need to realize that it may never exactly equal .33. So you probably want to check to see if it's <= .33. If so, then print the message and set a boolean variable to remember that you already printed it.

Also note that if gas is an integer type then you need to first convert it to a float:

if ((float)gas / fulltank == 0.33)

Upvotes: 1

trojanfoe
trojanfoe

Reputation: 122421

There is no percentage operator in Java (it is used as the Modulo operator - the amount left over after a division) so you have to calculate the percentage yourself.

Unfortunately, from your code, I cannot work out what gas should be compared to in order to determine if it's 33% the way there.

Upvotes: 3

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