Question

Do I need "import java." to use built in method? "import java.io, import java.lang"

Answer 1

Let's see from scratch when we code in c we need to include or say import stdio that is standard input and output. When we talk of java the case is same but at times we can say we don't need to import java.io to write simple programs as we write in compiler which include them by itself but when we code in notepad we need to import every single packages we are using. Let's see an example

public class LangTest {
   public static void main(String args[]) {
      int num = 100;
      double result = Math.sqrt(num);
      System.out.println("Square root of the number: "+result);
   }
}

Output

Square root of the number: 10.0

If you observe the above example here we haven’t imported the lang package explicitly but, still, we are able to calculate the square root of a number using the sqrt() method of the java.lang.Math class.

When we code in notepad we need to import every single package but when we code in online compilers or specific editors of java we don't need to add built in packages like java.io or so!!!