In java, the compiler throws an error if you try to assign a double literal to an int variable. However, it allows the assignment of an int literal to variable of type long.
double d = 4.0;
float f = d; // this is not allowed. 4.0 should be 4.0f
int i = 4;
long x = i; // this is allowed. 4 is treated same as 4L
Because an int fits inside a long, but if you put a double inside a float you may lose precision (it's a narrower type).
If you really must you can force this via casting
double d = 4.0;
float f = (float)d; // this is allowed
Because they are of different types and widths. Since you are losing precision going from a double to a float or an long to a int you need to downcast.
double d = 4.0;
float f = (float)d;
long i = 4;
int x = (int)i;
For the integer types, you can detect overflow by calling Math.toIntExact, and trapping for ArithmeticException.
try{
int myInt = Math.toIntExact( myLong )
} catch (ArithmeticException e) {
…
}
intandlongthe wrong way round, meaning you're not doing a fair comparison. If you hadlong i = 4; int x = i;then you'd have the same issue.double d = f;.long x = 4L; int i = x;will not work either