Computer Science 2

/** Valid and invalid code used for an exercise to identify proper and improper coding syntax and guidelines.  
 * @author:      Hyrum D. Carroll
 * @version:     0.2 (September 14, 2019)
 */
public class VariablesExercise {
    public static void main (String[] args) {

	int peopleInAmerica = 325,782,231;  /* Source: United States Census Bureau */

	double gross_domestic_product = 19.39e12;  //  USD (2017) Source: Bureau of Labor Statistics
	double unemploymentRate = 4.0%;  // (Feb 2019) Source: Bureau of Labor Statistics

	int gdppc = gross_domestic_product/peopleInAmerica;

	System.out.println("The gross domestic product per person (in the United States of America) is " + gdppc);
    }
}

public static boolean echo( int num){
    System.out.println("\techo(" + num + ")");
    return true;
}

public static void main (String[] args) {

    System.out.println("false &&");

    if( false && echo( 0 ) ){
        System.out.println( "\tfalse && echo(0)");
    }else if( true && echo( 1 ) ){
        System.out.println( "\ttrue && echo(1)");
    }else{
        System.out.println( "\telse");
    }

    System.out.println();
    System.out.println("true &&");
    if( true && echo( 2 ) ){
        System.out.println( "\ttrue && echo(2)");
    }else if( false && echo( 3 ) ){
        System.out.println( "\tfalse && echo(3)");
    }else{
        System.out.println( "\telse");
    }


    System.out.println();
    System.out.println("false ||");
    if( false || echo( 3 ) ){
        System.out.println( "\tfalse || echo(3)");
    }else if( true || echo( 4 ) ){
        System.out.println( "\ttrue || echo(4)");
    }else{
        System.out.println( "\telse");
    }

    System.out.println();
    System.out.println("true ||");
    if( true || echo( 1 ) ){
        System.out.println( "\ttrue || echo(1)");
    }else if( false || echo( 0 ) ){
        System.out.println( "\tfalse || echo(0)");
    }else{
        System.out.println( "\telse");
    }

}

Math.round( number * 10.0 ) / 10.0;

Math.round( number * 10 ) / 10.0;