how many null aware operator types are in flutter code example

Example 1: dart null aware operator ??

print(1 ?? 3); // <-- Prints 1.
print(null ?? 12); // <-- Prints 12.

int a; // The initial value of a is null.
a ??= 3;
print(a); // <-- Prints 3.

a ??= 5;
print(a); // <-- Still prints 3.

Example 2: dart terbary

int minVal = (a < b) ? a : b;	// if(a < b) {minVal = a;} else {minVal = b;}

var x = y ?? z;  				// assign y to x if y is not null, else z
var x ??= y;    				// assign y to x only if x is null
myObject?.myProp				// (myObject != null) ? myObject.myProp : null
myObject?.myProp?.someMethod()  // chainable