問題描述
我知道這樣的話題被問了好幾次，但我的問題是關于完整的 32 位 int 的溢出.例如:
I know such topic was asked several times, but my question is about overflow on full 32 bits of int. For example:
11111111111111111111111111111111 +
00000000000000000000000000000001 =
00000000000000000000000000000000 //overflow!
我發現 topic 有類似的問題，但是算法并不完美.
I found topic with similar question about this, however the algorithm is not perfect.
11111111111111111111111111111111 +
00000000000000000000000000000000 =
00000000000000000000000000000000 //overflow!
有沒有什么簡單、快速、安全的檢查方法?
Is there any simple, fast, safer way to check this ?
推薦答案
Math.addExact 溢出時拋出異常
從 Java 8 開始，數學類:
Math.addExact throws exception on overflow
Since Java 8 there is a set of methods in the Math class:
toIntExact(long)addExact(int,int)subtractExact(int,int)multiplyExact(int,int)
……以及長期版本.
這些方法中的每一個都會拋出 ArithmeticException 如果發生溢出.否則，如果它在范圍內，它們會返回正確的結果.
Each of these methods throws ArithmeticException if overflow happens. Otherwise they return the proper result if it fits within the range.
加法示例:
int x = 2_000_000_000;
int y = 1_000_000_000;
try {
int result = Math.addExact(x, y);
System.out.println("The proper result is " + result);
} catch(ArithmeticException e) {
System.out.println("Sorry, " + e);
}
查看此在 IdeOne.com 上實時運行的代碼.
對不起，java.lang.ArithmeticException:整數溢出
Sorry, java.lang.ArithmeticException: integer overflow
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