3 / 100DaysOfFlutter: Dart Sound Null Safety, Null Assign, Null Check, Everything null.

Learning null Safety in Dart:

understanding why we need null Safety; Null means nothing is there. so handle the programme at any point in time if there is a value which is null what should be performed?

Sound NullSafety:

By sound you might is understand that here you may know when the value will be null; so for that flow, we use SOUND Null Safety

 int i = 0;
 i= null; ❌
  // here i is 0; but what if somepoint it becomes null;
  // then it will throw an error
  // so we need to add a check for null
  <!-- down arrow unicode -->

  int❓ j = 1;
    //^ this is a nullable variable; so in future it can be null; and wount' throw error.   
    // make any value nullable by adding ❓after the variable type.  
  j = null; ✅

List<String> names = ['Ram', 'Shyam', 'Hari'];
names[0] = null; ❌


List<String?> names2 = ['Ram', 'Shyam', null];
names2[0] = null; ✅

List<String>? names3 = ['Ram', 'Shyam', 'Hari'];
names3 = null ✅
// for making a list nullable we need to add ? after the list type here it is String.

List<String?>? names4 = [null, null, "Ram"]; ✅
// Here List as well as list Type is also nullable.

Null Assign:

Null Assign means if the value is null Assign this value

int? age = 12;
age = null;

int RealAge = age ?? 18;
// adding this ❓❓ after the variables (age) makes us sure that if any case the value of age is null the RealAge will be 18; 

Null Check

Null check is a process of checking if the value is null or not, and perform tasks accordingly.

List<String>? names5 = null;
print(names5?.length);

// it is shortcut for
if(names5 != null) {
  print(names5.length);
} else {
  print("null");
}

print(Person?.skills?.length);✅
.❓.❓.❓
// it will only print the length of skills if the person is not null and if the skills are not null.

I will explain Objects; Classes in the next blog.

Share with me if anything is missing or you don't understand; don't shy 🥺

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Check the code for today here.
Repo

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