JNI:将unsigned int转换为jint [英] JNI: converting unsigned int to jint

问题描述

如何将unsigned int转换为jint?我是否必须完全转换它，还是可以不做任何特殊处理就将其退回?这基本上是我现在的代码，但是由于我尚未在本地设置JNI，因此我无法对其进行测试.

How do I convert an unsigned int to jint? Do I have to convert it at all, or can I just return it without any special treatment? This is basically my code right now, but I can't test it, as I haven't setup JNI locally.

JNIEXPORT jint JNICALL
Java_test_test(JNIEnv* env, jobject obj, jlong ptr)
{
    MyObject* m = (MyObject*) ptr; 
    unsigned int i = m->get(); 
    return i; 
}

推荐答案

在一般情况下，jint等同于int，因此可以容纳unsigned int值的一半.转换将以静默方式进行，但是如果jint值为负或unsigned int值大于jint可以容纳的最大值，则结果将不是您期望的.

In the general case, jint is equivalent to int, and so can hold about half the values of unsigned int. Conversion will work silently, but if a jint value is negative or if an unsigned int value is larger than the maximum value a jint can hold, the result will not be what you are expecting.

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