Question

I have a while loop that isn’t executing. I don’t believe there is an infinite loop or priming problem, but is there? I can’t find my logical error!

public class Test
{
    public static void main (String [] args)
    {
        int i = 1;
        int j = 1;
        while  ((i < 10) && (j*j != 25));
        { 
           i++;  
           ++j;
           System.out.println( i * j );
        }   
    }
}

Answer 1

Remove the semicolon after the while loop

public static void main (String [] args)
{
     int i = 1;
     int j = 1;
     while  ((i < 10) && (j*j != 25)) //Semicolon removed from here
     { 
        i++;  
        ++j;
        System.out.println( i * j );
     }   
}

Any statement that directly comes after the loop declaration is considered the whole block if it’s not enclosed with braces.

I.E

if( true ) 
    System.out.println( "hello" );
    System.out.println( "world" );

Is treated as

if( true ) {
     System.out.println( "hello" );
}
System.out.println( "world" );

A single semicolon is considered as empty statement and thus made up your whole loop body.