[英]value of the local variable not used
我正在学习Java,并且在课堂上我们开始使用多个类。...我的雇员类具有默认构造函数。 在其中,我具有默认值的变量。 我的问题是未使用默认构造函数中变量的值,因此在变量下出现黄色下划线。 有人可以指引我正确的方向。
package week2;
import java.text.NumberFormat;
public class Employee {
//Instance Variables
private String firstName = "", lastName = "";
private char gender = 'U';
private int dependents = 0;
private double annualSalary = 0;
//Default Employee Constructor
public Employee() {
String firstName = "not given";
String lastName = "not given";
char gender = 'U';
int dependents = 0;
double annualSalary = 20000;
} //End of default Employee Constructor
//Employee Constructor with variables
public Employee(String firstName, String lastName, char gender, int dependents, double salary) {
this.firstName = firstName;
this.lastName = lastName;
this.gender = gender;
this.dependents = dependents;
this.annualSalary = salary;
} //End of Overloaded Employee Constructor
//Calculate Pay
public double annualSalary() {
return (getAnnualSalary() / 52);
} //End Calculate Pay
//Display Employee
public void displayEmployee() {
NumberFormat nf = NumberFormat.getCurrencyInstance();
System.out.println("First Name: \t" + this.firstName);
System.out.println("Last Name: \t" + this.lastName);
System.out.println("Gender: \t" + this.gender);
System.out.println("Dependents: \t" + this.dependents);
System.out.println("Annual Salary: \t" + nf.format(this.annualSalary));
System.out.println("Weekly Pay: \t" + nf.format(annualSalary()));
} //End Display Employee
//Getters and Setters
//Get-Set firstName
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
//Get-Set lastName
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
//Get-Set Gender
public char getGender() {
return gender;
}
public void setGender(char gender) {
this.gender = gender;
}
//Get-Set dependents
public int getDependents() {
return dependents;
}
public void setDependents(int dependents) {
this.dependents = dependents;
}
//Get-Set annualSalary
public double getAnnualSalary() {
return annualSalary;
}
public void setAnnualSalary(double annualSalary) {
this.annualSalary = annualSalary;
}
}
您正在默认构造函数中创建local variables
。 删除声明,它将为类级变量赋值。
//Default Employee Constructor
public Employee() {
firstName = "not given";
lastName = "not given";
gender = 'U';
dependents = 0;
annualSalary = 20000;
} //End of default Employee Constructor
注意:黄色表示警告。 在您的情况下,它暗示您正在创建局部变量并为其分配值,这在您的构造函数中未使用,并且局部变量在构造函数之外不可见。
如果未使用相同的名称定义其他本地变量,则可以使用this.firstName
或firstName
。 (在您的情况下,您可以在默认构造函数中同时使用它们)
如果使用相同的名称定义了某些局部变量,则firstName
指代局部变量,而this.firstName
指代类级变量。(您可以在参数化的构造函数中看到这一点)
正如编译器所说,no-arg构造函数声明新变量,它们被初始化但未被使用。 请注意,这些变量不是类中的字段。
public Employee() {
//this is a local variable in the method
String firstName = "not given";
//this variable is not the same as this:
this.firstName = "not given";
//same for other variables
}
这种情况有两种解决方案:
删除所有局部变量的声明,并改用字段:
public Employee() { this.firstName = "not given"; //... }
使用this()
并使用字段的初始值调用其他构造函数:
public Employee() { this("not given", "not given", 'U', 0, 2000); }
在这里,您必须清楚的概念是变量的范围,在默认构造函数中
//Default Employee Constructor
public Employee() {
String firstName = "not given";
String lastName = "not given";
char gender = 'U';
int dependents = 0;
double annualSalary = 20000;
} //End of default Employee Constructor
声明的变量仅在此构造函数中具有作用域,它们不同于在类的开头声明的实例变量。 因此,这些变量不会在任何地方使用,因此会出现编译器警告。
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