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);
 
	}
}