Android-从另一个类调用布尔值

Question

If I set a value to true in one class, such as

static boolean mIsPremium = true;

I only get the correct value sometimes, as in if I use double equal signs (==) I will always return the true value.

if (firstClass.mIsPremium == true){
    do stuff
} else {
    do other stuff
}

If I only use one equal sign (=) it will return a true value, this happens when I set mIsPremium to false in the first class.

if (firstClass.mIsPremium = true){
    do stuff
} else {
    do other stuff
}

I have tried many configurations, using two = signs, using one = sign, including a new boolean in the second class that has its own value dependant upon the first boolean's value... Nothing I do seems to work correctly.

How do I call a boolean value from another class and have the value correctly used in the second class. If it's true I want it true in the second class, if its false I want it false in the second class.

Answer 1

you are confused with the operators .

=

Is assigns the value

==

checks for the equality

if (firstClass.mIsPremium = true){

The above line considering it as a statement and assigns the value true to mIsPremium and proceeding further.

if (firstClass.mIsPremium == true){ 

Checks if the values of two operands are equal or not, if yes then condition becomes true.

What you do is

if (firstClass.mIsPremium){
    do stuff
} else {
    do other stuff
}

Answer 2

One = sing is an assignment, an assignment in always true.

(a = b) #-> always true, it doesn't matter if a or b are false or true

Two = sing is a comparison, the result depends on what are the values of a and b.

(a == b) #-> true if and only if a has the same value of b

Answer 3

Boolean can only have two values as true/false.No need to use == or =

just use

if (firstClass.mIsPremium)     //if mIsPremium is true
{     
    do stuff
} else {
    do other stuff
}

Answer 4

you do not need to use any = signs you can just do

if(firstClass.mIsPremium) { } // check for premium

or

if(!firstClass.mIsPremium) { } // check for not premium