Division by Zero in Java

Java does not stop you dividing by zero but, if you try, it gives you a run-time error:

 

Java > cat prog81.java

public class prog81

{

public static void main (String args[])

  {

  int x = 1/0;

  System.out.println("x = " + x);

  }

}

Java > javac prog81.java

Java > java prog81

Exception in thread "main" java.lang.ArithmeticException: / by zero

        at prog81.main(prog81.java:5)

Java >

 

You can trap these errors and handle them tidily as shown below. This stops your program falling over:

 

Java > cat prog82.java

public class prog82

{

public static void main (String args[])

  {

  try

    {

    System.out.println("Dividing 1 by 0");

    int x = 1/0;

    System.out.println("x = " + x);

    }

  catch (ArithmeticException e)

    {

    System.out.println("Division by zero not allowed");

    }

  try

    {

    System.out.println("Dividing 1 by 1");

    int y = 1/1;

    System.out.println("y = " + y);

    }

  catch (ArithmeticException e)

    {

    System.out.println("Division by zero not allowed");

    }

  }

}

Java > javac prog82.java

Java > java prog82

Dividing 1 by 0

Division by zero not allowed

Dividing 1 by 1

y = 1

Java >

 

However, if you divide 1.0 by 0.0, the answer is infinity:

 

Java > cat prog83.java

public class prog83

{

public static void main (String args[])

  {

  double x = 1.0/0.0;

  System.out.println("x = " + x);

  }

}

Java > javac prog83.java

Java > java prog83

x = Infinity

Java >

... and, if you divide 0.0 by 0.0, the answer is NaN (not a number):

andrew@UBUNTU:~/Java$ cat prog84.java
public class prog84
{
public static void main (String args[])
  {
  double x = 0.0/0.0;
  System.out.println("x = " + x);
  }
}
andrew@UBUNTU:~/Java$ javac prog84.java
andrew@UBUNTU:~/Java$ java prog84
x = NaN
andrew@UBUNTU:~/Java$

Command Line Parameters in Java (1)

You can pass parameters from the command line to a Java program as shown below. In the final example, a parameter of -1 is supplied. The square root of -1 is a complex number if I remember correctly. The answer given, NaN, stands for not a number:

andrew@UBUNTU:~/Java$ cat prog34.java

public class prog34
{
public static void main(String[] args)
  {
  double x = Double.parseDouble(args[0]);
  System.out.println
  ("The square root of " + x     
   + " is " + Math.pow(x,0.5));
  }
}
andrew@UBUNTU:~/Java$ javac prog34.java
andrew@UBUNTU:~/Java$ java prog34 4
The square root of 4.0 is 2.0
andrew@UBUNTU:~/Java$ java prog34 10
The square root of 10.0 is 3.1622776601683795
andrew@UBUNTU:~/Java$ java prog34 -1
The square root of -1.0 is NaN
andrew@UBUNTU:~/Java$