Does native methods in Java, operating system specific?

Question

Problem Description : - During one discussion I found that programmer stuck at point and I thought I should put on forum.

Today I was searching array conversion into char array. And I checked definition of toCharArray() method of string class.

char str[] = "native".toCharArray();

toCharArray() definition : -

public char[] toCharArray() {
    char result[] = new char[count];
    getChars(0, count, result, 0);
    return result;
}

getChars definition: -

public void getChars(int srcBegin,int srcEnd,char dst[],int dstBegin){
   if(srcBegin<0){
       throw new StringIndexOutOfBoundsException(srcBegin);
   }
   if(srcEnd>count){
       throw new StringIndexOutOfBoundsException(srcEnd);
   }
   if(srcBegin>srcEnd){
       throw new StringIndexOutOfBoundsException(srcEnd-srcBegin);
   }
   System.arraycopy(value,offset+srcBegin,dst,dstBegin,srcEnd-srcBegin);
}

Then a native method: -

public static native void arraycopy(Object src,  int  srcPos,
                                        Object dest, int destPos,
                                         int length);

Here I don't have to understand native but I have to know In such a native method define here in a same way different native method will define for other operating system.

Answer 1

The reason it's native is because this otherwise expensive function can be heavily optimized by using native code.

But the behavior is the same whatever the OS.