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[英]Null check Operator used on a null value. Can't figure out how to not display an image if _pickedImage is null
[英]null check cant get out of this
伙計們我無法擺脫這個。你能檢查一下並告訴我我應該放 null 檢查的地方嗎? 這是為了正式分享帖子。我不想確定下面的名字年齡和薪水。
class _Employee {
String? empName;
int? empAge;
int? empSalary;
String get employeeName {
return empName!;
}
void set employeeName(String name) {
this.empName = name;
}
void set employeeAge(int age) {
if (age == null) {
print("please give a number");
} else if (age <= 18) {
print("please give a value number");
this.empAge = age;
}
}
int get employeeAge {
return empAge!;
}
void set employeeSalary(int salary) {
salary <= 0
? print("Salary cannot be less than 0")
: this.empSalary = salary;
}
int get employeeSalary {
return empSalary!;
}
}
void main() {
_Employee emp = _Employee();
emp.employeeName;
emp.employeeAge;
emp.employeeSalary;
print("Employee's Name is : ${emp.employeeName}");
print("Employee's Age is : ${emp.employeeAge}");
print("Employee's Salary is : ${emp.employeeSalary}");
}
您可以將返回數據類型更改為可為空,而不是使用 null-assert !
.
String? get employeeName {
return empName;
}
或者您可以在 null 案例中返回默認值。
String get employeeName {
return empName ?? "Got null on empName";
}
你需要像這樣設置值
emp.employeeName = "Test";
完整的片段可以是
class _Employee {
String? empName;
int? empAge;
int? empSalary;
String get employeeName {
return empName ?? "Got null on empName";
}
set employeeName(String name) {
empName = name;
}
set employeeAge(int? age) {
if (age == null) {
print("please give a number");
} else if (age <= 18) {
print("please give a value number");
empAge = age;
}
}
int get employeeAge {
return empAge ?? 0;
}
set employeeSalary(int salary) {
salary <= 0 ? print("Salary cannot be less than 0") : empSalary = salary;
}
int get employeeSalary {
return empSalary ?? 0;
}
}
void main() {
_Employee emp = _Employee();
emp.employeeName = "Test";
emp.employeeAge = 12;
emp.employeeSalary;
print("Employee's Name is : ${emp.employeeName}");
print("Employee's Age is : ${emp.employeeAge}");
print("Employee's Salary is : ${emp.employeeSalary}");
}
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