While - Java

Definition §

A while loop runs while a condition is met.

// Define a variable to use as a stopping mechanism
boolean _condition_ = false;
 
while(_conditionMet_){
	statement until condition met, where done = false;
}

While loops are read much easier than for loops. “While _conditionMet_ is true, do something.” This can be a little wonky at the beginning, but it’s important to remember that while loops only run while something is true. The logic to flip that switch to false will be inside the loop itself.

An intuitive example of this is as follows:

boolean done = false;
 
while (!done){
	for (int i = 0; i < 5; i++){
		System.out.println("Not done yet!");
	}
	done = true;
}

We receive the following output:

Not done yet!
Not done yet!
Not done yet!
Not done yet!
Not done yet!
Done!

So, while we are not done (!done), we print ”Not done yet!”, and after five cycles, we set done = true and terminate the loop.

See: Applications.

Applications §

public class experiment{
  public static void main(String[] args){
    int year = 0;
    double balance = 1000;
    double interest = .05;
    
    while (balance < 10000){
	    year ++;
	    balance = (balance * interest) + balance;
    }
    
    System.out.printf("It took %d years to generate $%8.2f from interest.", year, balance);
  }
}

Print all squares less than n §

import java.lang.Math;
 
public class experiment{
  public static void main(String[] args){
    int upperBound = 100;
    int initial = 1;
    while (Math.pow(initial,2) < upperBound){
      if (Math.pow(initial, 2) % initial == 0){
        System.out.println(Math.pow(initial,2));
        initial ++;
      } else {
        initial ++;
      }
    }
  }
}
 
OR
 
import java.lang.Math;
 
public class experiment{
  public static void main(String[] args){
    int upperBound = 100;
    int initial = 0;
    while (Math.pow(initial,2) < upperBound){
        System.out.println(Math.pow(initial,2));
        initial ++;
    }
  }
}

Output:

1.0
4.0
9.0
16.0
25.0
36.0
49.0
64.0
81.0

Print all values less than n evenly divisible by 10 §

public class experiment{
  public static void main(String[] args){
    int n = 100;
    int divisor = 10;
    int initial = 1;
    while (initial < n){
      if(initial % divisor == 0){
        System.out.println(initial);
        initial ++;
      } else {
        initial ++;
      }
    }
  }
}

Output:

0
10
20
30
40
50
60
70
80
90