system.out.println 上的语法错误？

Question

这适用于双精度类型的常量。

我的 system.out.println 代码出现此语法错误：

标记“;”的语法错误，@预期

谢谢！

public final class Netpay {

public static void main(String[] args) {
    // TODO Auto-generated method stub

public static final double FEDERAL_TAX_PERCENT = 10.00;
public static final double STATE_TAX_PERCENT = 4.5;
public static final double SS_PERCENT = 6.2;
public static final double MEDICARE_PERCENT = 1.45;
public static final double PAY_PER_HOUR = 7.25;



    int hoursPerWeek = 40;

    double grossPay = hoursPerWeek * PAY_PER_HOUR;
    double federalTax = grossPay * FEDERAL_TAX_PERCENT / 100;
    double stateTax = grossPay * STATE_TAX_PERCENT / 100;
    double medicare = grossPay *  MEDICARE_PERCENT / 100;
    double socialSecurity = grossPay * SS_PERCENT / 100;
    double netPay = grossPay -  (federalTax + stateTax + medicare + socialSecurity);

    system.out.println("Hours Per Week = 40");
    system.out.println("Gross Pay= grossPay");
    system.out.println("Net Pay = netPay");

    system.out.println("Deductions:");
    system.out.println("Federal= federalTax");
    system.out.println("State = stateTax");
    system.out.println("Social Security = socialSecurity");
    system.out.println("Medicare = medicare");


}

Answer 1

将常量移出main 方法：

public final class Netpay {

    public static final double FEDERAL_TAX_PERCENT = 10.00;
    public static final double STATE_TAX_PERCENT = 4.5;
    public static final double SS_PERCENT = 6.2;
    public static final double MEDICARE_PERCENT = 1.45;
    public static final double PAY_PER_HOUR = 7.25;

    public static void main(String[] args) {
        // the rest of your code goes here
    }
}

如前所述，让系统有一个大写的 S：System.out.println。

Answer 2

理解这个概念——在方法中使用public 和static 是没有意义的。由于在方法中所有变量都是本地的，所以没有任何公共、私有、受保护等。现在，Java 中的静态意味着在 JVM 的生命周期中将保留在堆区域中的东西。现在由于内部方法，变量和对象是本地的，并且一旦方法执行完成就会被垃圾收集（直到你传递它们的引用等），所以也没有静态的意义。 您不能在方法内部使用静态，无论是静态方法还是实例方法。

1.始终将应用程序不同部分可能需要的常量保存在一个常量文件中。如果您不需要它，那么最好根据需要将其作为方法内部的局部变量或实例变量。
可以使用 {classname} 从应用程序中的任何位置访问静态实例变量。{variable_name}
因此，您的常量 Java 文件可能是：

public class ApplicationConstants {
    public static final double FEDERAL_TAX_PERCENT = 10.00;
    public static final double STATE_TAX_PERCENT = 4.5;
    public static final double SS_PERCENT = 6.2;
    public static final double MEDICARE_PERCENT = 1.45;
    public static final double PAY_PER_HOUR = 7.25;
}

2.System.out.println() 是在控制台打印一些东西，它接受的参数是一个字符串。因此，如果您将任何内容放在引号内，那么它将是一个字符串（这就是您得到结果为Gross Pay= grossPay 的原因），您想打印一个动态值，然后使用“+”运算符附加它。

public static void main(String[] args) {
            int hoursPerWeek = 40;

            double grossPay = hoursPerWeek * ApplicationConstants.PAY_PER_HOUR;
            double federalTax = (grossPay * ApplicationConstants.FEDERAL_TAX_PERCENT) / 100;    //Corrected your formula - (A+B)/C
            double stateTax = (grossPay * ApplicationConstants.STATE_TAX_PERCENT) / 100;        //Corrected your formula - (A+B)/C
            double medicare = (grossPay * ApplicationConstants.MEDICARE_PERCENT) / 100;         //Corrected your formula - (A+B)/C
            double socialSecurity = (grossPay * ApplicationConstants.SS_PERCENT) / 100;         //Corrected your formula - (A+B)/C
            double netPay = grossPay
                    - (federalTax + stateTax + medicare + socialSecurity);

            System.out.println("Hours Per Week = " + hoursPerWeek);
            System.out.println("Gross Pay = " + grossPay);
            System.out.println("Net Pay = " + netPay);

            System.out.println("Deductions:");
            System.out.println("Federal = " + federalTax);
            System.out.println("State = " + stateTax);
            System.out.println("Social Security = " + socialSecurity);
            System.out.println("Medicare = " + medicare);
        }