System.arraycopy方法解釋

yexiaobai 發(fā)布于2019-08-16 13:56 / 1901人閱讀

摘要：源數(shù)組源數(shù)組要復(fù)制的起始位置目標(biāo)數(shù)組將原數(shù)組復(fù)制到目標(biāo)數(shù)組目標(biāo)數(shù)組起始位置從目標(biāo)數(shù)組的哪個(gè)下標(biāo)開(kāi)始復(fù)制操作復(fù)制源數(shù)組的長(zhǎng)度例子如下源數(shù)組為目標(biāo)數(shù)組為開(kāi)始執(zhí)行數(shù)組復(fù)制操作將源數(shù)組從數(shù)組下標(biāo)開(kāi)始的位長(zhǎng)度的數(shù)組復(fù)制到目標(biāo)數(shù)組從下標(biāo)為的位置開(kāi)始復(fù)制

**/*
 * @param      src      the source array.源數(shù)組
 * @param      srcPos   starting position in the source array.源數(shù)組要復(fù)制的起始位置
 * @param      dest     the destination array.目標(biāo)數(shù)組（將原數(shù)組復(fù)制到目標(biāo)數(shù)組）
 * @param      destPos  starting position in the destination data.目標(biāo)數(shù)組起始位置（從目標(biāo)數(shù)組的哪個(gè)下標(biāo)開(kāi)始復(fù)制操作）
 * @param      length   the number of array elements to be copied.復(fù)制源數(shù)組的長(zhǎng)度
 * @exception  IndexOutOfBoundsException  if copying would cause
 *               access of data outside array bounds.
 * @exception  ArrayStoreException  if an element in the src
 *               array could not be stored into the dest array
 *               because of a type mismatch.
 * @exception  NullPointerException if either src or
 *               dest is null.
 */
public static native void arraycopy(Object src,  int  srcPos,Object dest, int destPos,int length);**

例子如下：

package test.demo;

    public class ArrayCopyTest {
        
        
        public static void main(String[] args) {
            char[] src = new String("hellow").toCharArray();
            char[] dest = new String("12345789").toCharArray();
            
            System.out.print("src源數(shù)組為：");
            for(char c : src){
                System.out.print(c);
            }
            
            System.out.print("
dest目標(biāo)數(shù)組為：");
            for(char c : dest){
                System.out.print(c);
            }
            
            /*
             * 開(kāi)始執(zhí)行數(shù)組復(fù)制操作
             * 將源數(shù)組["h","e","l","l","o","w"]從數(shù)組下標(biāo)0開(kāi)始的4位長(zhǎng)度的數(shù)組["h","e","l","l"]
             * 復(fù)制到目標(biāo)數(shù)組["1","2","3","4","5","6","7","8"],從下標(biāo)為3的位置開(kāi)始
             */
            System.arraycopy(src,0,dest,3,4);
            
            System.out.print("
復(fù)制完成之后的目標(biāo)數(shù)組為：");
            for(char c : dest){
                System.out.print(c);
            }
        }
    }

結(jié)果輸出如下：
src源數(shù)組為：hellow
dest目標(biāo)數(shù)組為：12345789
復(fù)制完成之后的dest目標(biāo)數(shù)組為：123hell9