package another;
import java.util.Arrays;
import java.util.List;
/**
* 数组知识回顾
* @author ChristineBassoon
*/
public class Array {
public static void main(String[] args) {
//1. 新建数组的三种方式
int[] arr1 = new int[3];
int[] arr2 = {3,2,4,1};
int[] arr3 = new int[]{5,7,9,0,3,5};
//填充数组
Arrays.fill(arr1, 10);//[10,10,10]
//2. 数组元素默认值
int[] arr_int = new int[3];//[0,0,0]
String[] arr_str = new String[3];//[null,null,null]
//3. 输出数组内容,如：[0,0,0,0]
Arrays.toString(arr1);
/*4. 数组自动排序（从小到大）
* 一、 数组全排序 Arrays.sort(T[])
* 二、 特定位置排序 Arrays.sort(T[], fromIndex, toIndex);
*/
Arrays.sort(arr2);//[1,2,3,4]
Arrays.sort(arr3,1,3);//只排序下标1-3的元素 [5,0,7,9,3,5]
//5. 数组扩容、复制等————基于方法System.arraycopy(src, srcPos, dest, destPos, length);
/*
* (1) 扩容
* Arrays.copyOf(original, newLength)
* 扩充的元素加至原序列末尾
*/
int[] arr4 = Arrays.copyOf(arr2, arr2.length+2);//[1,2,3,4,0,0]
/*
* (2) 缩容
* Arrays.copyOf(original, newLength)
* 根据指定长度，只保留原数组的头部
*
*/
int[] arr5 = Arrays.copyOf(arr2, 2);// [1,2]
/*
* (3) 截取(同数组中)
* Arrays.copyOfRange(original, from, to)
* 范围为[from,to)，超出则抛IllegalArgumentException异常
*/
int[] arr6 = Arrays.copyOfRange(arr2, 1, 3);//[2,3]
/*
* 用外部数组元素替换本数组指定位置
* System.arraycopy(src, srcPos, dest, destPos, length); length表示需要复制的元素个数
*/
String[] t1 = {"a","b","c","d"};
String[] t2 = {"Apple","Boy","C","D"};
System.arraycopy(t1, 1, t2, 2, 1);
System.out.println(Arrays.toString(t2));//[Apple, Boy, b, D]
//数组转换为List类型
List list = Arrays.asList(arr2);
}
}
