在 Java 中安全地将 long 转换为 int [英] Safely casting long to int in Java

问题描述

Java 中验证从 long 到 int 的转换不会丢失任何信息的最惯用的方法是什么?

What's the most idiomatic way in Java to verify that a cast from long to int does not lose any information?

这是我目前的实现:

public static int safeLongToInt(long l) {
    int i = (int)l;
    if ((long)i != l) {
        throw new IllegalArgumentException(l + " cannot be cast to int without changing its value.");
    }
    return i;
}

推荐答案

Java 8 添加了一种新方法来实现这一点.

A new method has been added with Java 8 to do just that.

import static java.lang.Math.toIntExact;

long foo = 10L;
int bar = toIntExact(foo);

在溢出时会抛出一个 ArithmeticException.

Will throw an ArithmeticException in case of overflow.

参见:Math.toIntExact(long)

Java 8 中添加了其他几种溢出安全方法.它们以 exact 结尾.

Several other overflow safe methods have been added to Java 8. They end with exact.

示例:

• Math.incrementExact(long)
• Math.subtractExact(long, long)
• Math.decrementExact(long)
• Math.negateExact(long),
• Math.subtractExact(int, int)

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