title: How to check the input is an integer or not in Java?
body: <p>In my program I want an integer input by the user. I want an error message to be show when user inputs a value which is not an integer.
  How can I do this. 
  My program is to find area of circle. In which user will input the value of radius. But if user inputs a character I want a message to be shown saying Invalid Input. </p>
  
  <p>This is my code:</p>
  
  <pre><code>int radius, area;
  Scanner input=new Scanner(System.in);
  System.out.println("Enter the radius:\t");
  radius=input.nextInt();
  area=3.14*radius*radius;
  System.out.println("Area of circle:\t"+area);
  </code></pre>