ArrayCopy方法[Java]

作为小白一直在使用for循环对数组进行复制，添加和删除，学习过程中发现ArrayCopy（）方法在对数组进行删除，添加的时候更加高效，便利。

ArrayCopy（）

作为小白一直在使用for循环对数组进行复制，添加和删除，学习过程中发现ArrayCopy（）方法在对数组进行删除，添加的时候更加高效，便利。

我们先来看一下底层源码：

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

/**
 * Returns the same hash code for the given object as
 * would be returned by the default method hashCode(),
 * whether or not the given object's class overrides
 * hashCode().
 * The hash code for the null reference is zero.
 *
 * @param x object for which the hashCode is to be calculated
 * @return  the hashCode
 * @since   1.1
 * @see Object#hashCode
 * @see java.util.Objects#hashCode(Object)
public static native void arraycopy(Object src,  int  srcPos,
                                    Object dest, int destPos,
                                    int length);

/**
 * Returns the same hash code for the given object as
 * would be returned by the default method hashCode(),
 * whether or not the given object's class overrides
 * hashCode().
 * The hash code for the null reference is zero.
 *
 * @param x object for which the hashCode is to be calculated
 * @return  the hashCode
 * @since   1.1
 * @see Object#hashCode
 * @see java.util.Objects#hashCode(Object)
 */

src：要复制的数组(原数组)

srcPos：复制源数组的起始位置

dest：目标数组

destPos：目标数组的下标位置

length：要复制的长度

直观的说就是：

  • Arraycopy(被复制的数组, 从第几个元素开始复制, 要复制到的数组, 从第几个元素开始粘贴, 一共需要复制的元素个数);

使用ArrayCopy（）直接复制数组

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public class TestArrayCopy {
	public static void main(String[] args) {
		String[] s1 = {"aa","bb","cc","dd","ee"};
		String[] s2 = new String[10];
		
		System.arraycopy(s1,1,s2, 1, 3);
		
		for (int i = 0; i < s2.length; i++) {
			System.out.println(i+public class TestArrayCopy {
	public static void main(String[] args) {
		String[] s1 = {"aa","bb","cc","dd","ee"};
		String[] s2 = new String[10];
		
		System.arraycopy(s1,1,s2, 1, 3);
		
		for (int i = 0; i < s2.length; i++) {
			System.out.println(i+"--"+s2[i]);
		}
	}
}
  • 通过Arraycopy（）方法，把s1数组第一个位置复制到s2第一个位置中，复制长度3.

使用ArrayCopy（）删除数组中的蔡徐坤

给定一个明星数组，我们的目标是删除蔡徐坤。

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public class TestArrayCopy {
	public static void main(String[] args) {
		String[] s = {"胡歌","彭于晏","蔡徐坤","周润发","周星驰"};
		removeElement(s, 3);
	}
	public static String[] removeElement(String[] s,int index) {
		System.arraycopy(s,index,s,index-1,s.length-index);
		s[s.length-1] = null;
		for (int i = 0; i < s.length; i++) {
			System.out.println(i+"--"+s[i]);
		}
		public class TestArrayCopy {
	public static void main(String[] args) {
		String[] s = {"胡歌","彭于晏","蔡徐坤","周润发","周星驰"};
		removeElement(s, 3);
	}
	public static String[] removeElement(String[] s,int index) {
		System.arraycopy(s,index,s,index-1,s.length-index);
		s[s.length-1] = null;
		for (int i = 0; i < s.length; i++) {
			System.out.println(i+"--"+s[i]);
		}
		return s;
	}
	}

通过对数组进行自身的复制，我们成功的把蔡徐坤删除。