Four Assignments: Which Compile, and Which Lose Something

Four lines. For each one, decide whether the compiler accepts it as written, and if it does, whether anything is lost. Write your four answers down before opening the reveal.

java

long a = 2_000_000;
int b = 3_000_000_000L;
int c = (int) 3.99;
double d = 7;

Which of the four compile, and what does each one hold?

The four assignments, with what the compiler does and what survives
Line	Compiles?	Result
`long a = 2_000_000;`	Yes	Widening. `a` holds 2000000.
`int b = 3_000_000_000L;`	No	Narrowing from `long` to `int`, and the value is past `int`'s ceiling anyway.
`int c = (int) 3.99;`	Yes	The cast overrules the check. `c` holds 3 — truncated, not rounded.
`double d = 7;`	Yes	Widening. `d` holds 7.0.

The one worth noticing is the third. A cast never rounds; it throws away everything after the point. (int) -3.99 is −3, not −4, because truncation goes towards zero rather than downwards.

Java
JVM