package cn.tedu.demo;import java.util.Arrays;public class Demo04_2 {public static void test(){int[] a = {1,2,3,4,5};int[] b = new int[10];//b = {1,2,3,0,0,0,...}//狐族的拷贝//第一个参数：原数组//第二个参数：原数组元素的起始位置//第三个参数：目标数组//第四个参数：目标数组元素的起始位置//第五个参数：长度（拷贝元素的长度）//是静态方法
//		System.arraycopy(a, 0, b, 0, 3);
//		System.out.println(Arrays.toString(b));//练习：b = {0,0,3,4,0,.....}System.arraycopy(a, 2, b, 2, 2);System.out.println(Arrays.toString(b));}public static void test1(){//数组扩容//第一个参数：表示原数组（拷贝）//第二个参数：扩容之后的长度String[] names = {"张三"};names=Arrays.copyOf(names, names.length+1);names[1]="李四";System.out.println(Arrays.toString(names));}public static void test2(){//冒泡排序法int[] x = {23,56,22,15,45,8,16,29};for(int i = 0;i<x.length;i++){for(int j = 0;j<x.length-1;j++){if(x[j]>x[j+1]){x[j]=x[j]+x[j+1];x[j+1]=x[j]-x[j+1];x[j]=x[j]-x[j+1];}}}System.out.println(Arrays.toString(x));}//选择排序public static void test3(){int[] nums={23,56,22,15};for(int i = 0;i<nums.length-1;i++){for(int j = i+1;j<nums.length;j++){if(nums[i]<nums[j]){int temp =nums[i];nums[i]=nums[j];nums[j]=temp;}}}System.out.println(Arrays.toString(nums));}public static void test4(){int [][] nums;nums = new int[2][3];for(int i =0;i<nums.length;i++){for(int j = 0;j<nums[i].length;j++){System.out.print(nums[i][j]+"\t");}System.out.println();}}public static void test5(){//二维数组其它定义方式int[][] nums = new int[2][3];int[][] nums2 ={{1,2,3},{4,5,6}};int[][] nums3 = new int[][]{{1,2,3},{4,5,6}};}//不规则的二维数组public static void test6(){//必须有一个行存在才不会报错！int [][] nums = new int[3][];int [][] nums = new int[3][];nums[0] = new int[3];nums[1] = new int[1];nums[2] = new int[5];for(int i =0;i<nums.length;i++){for(int j = 0;j<nums[i].length;j++){System.out.print(nums[i][j]+"\t");}System.out.println();}}public static void main(String[] args) {test6();}
}