import java.util.Arrays;public class TestFive {//数组相关学习//相同的数据类型有序的放在一起；// 数据类型[] 数组名称=new 数据类型[]{存放指定数据类型的数据}//数据静态初始化,在创建数据组时已经确定有多少个元素public static void test(){//静态初始化，也可以写成//String[] names = {"zhangsan","lisi","wanger"};String[] names = new String[]{"zhangsan","lisi","wanger"};String[] stNames = {"zhangsan","lisi","wanger"};}public static void printList(String[] a){//打印数组内容Arrays.toString()方法String list = Arrays.toString(a);System.out.println(list);}public static void main(String[] args) {int a =10;//一个变量只能存一个值//数组可以存放相同数据类型的多个值//静态初始化数组int[] nums = new int[]{10,2,15,2}; //定义一个int类型的名字为nums的数组，索引从0开始//通过索引读取数组中对应的值System.out.println(nums[1]);//动态初始化数组,从空间申请一个5索引的空间动态数组String[] students = new String[5];//往动态数组中存放数据students[0] ="张三";students[1] = "李四";students[2] = "王二";students[3] = "麻子";students[4] = "张无忌";//students[101] = "王二"; //这样写数组越界报错，申请的只有100System.out.println(students[0]);System.out.println(students[1]);//获取数组长度lengthSystem.out.println(students.length);//遍历数组for循环,动态初始化的没有值的索引，其值为nullfor (int i = 0; i < students.length; i++) {System.out.println(students[i]);}//直接打印数组是一个对象地址System.out.println(students);printList(students);//倒序打印数组中的元素for (int i = students.length-1; i>=0 ; i--) {System.out.print(students[i]);System.out.print("\t");}//整一个冒泡排序//需要排序的数字放在一个数组中int[] numbers = {15,2,4,3,8,20};//升序for (int i = 0; i < numbers.length; i++) {for (int j = i; j <numbers.length-1; j++) {if(numbers[i]>=numbers[j+1]){int temp = numbers[j+1];numbers[j+1]=numbers[i];numbers[i] = temp;}}}System.out.println(Arrays.toString(numbers));//降序for (int i = 0; i < numbers.length; i++) {for (int j = i; j <numbers.length-1; j++) {if(numbers[i]<=numbers[j+1]){int temp = numbers[j+1];numbers[j+1]=numbers[i];numbers[i] = temp;}}}System.out.println(Arrays.toString(numbers));//冒泡排序int[] se = {2,5,13,18,6,1,0};for (int j = se.length-1; j >0; j--) {for (int i = 0; i < j; i++) {if(se[i]>se[i+1]){int temp = se[i];se[i] = se[i+1];se[i+1] = temp;}}}System.out.println(String.format("冒泡排序结果: %s",Arrays.toString(se)));//选择排序 逐步把最小的值排到第一 第二 第三int[] selectSort = {15,1,7,14,2,0};for (int i = 0; i < selectSort.length; i++) {//先排序第一轮，拿出第一个值依次和后面的比较,如果第一个小于后面的相互交换for (int j = i; j < selectSort.length-1; j++) {if(selectSort[i]>=selectSort[j+1]){int temp = selectSort[i];selectSort[i]=selectSort[j+1];selectSort[j+1]=temp;}}}System.out.println(String.format("选择排序结果: %s",Arrays.toString(selectSort)));//二分查找算法int[] twoSort = {0, 1, 2, 7, 14, 15,50,100,101};//查找1的索引值在数组中哪个位置System.out.println(Arrays.toString(twoSort));int find =50;int indexMax = twoSort.length-1;int indexMin = 0;for (int i = indexMin; i <indexMax; i++) {int midNum = twoSort[(indexMin+indexMax)/2];if(midNum>find){indexMax = (indexMin+indexMax)/2-1;}else if(midNum<find) {indexMin =(indexMin+indexMax)/2+1;}else {System.out.print(String.format("要查找的数据%s 在数组中的索引位置为:",find));System.out.println((indexMin+indexMax)/2);break;}}//二分查找法int f = 50;int max = twoSort.length-1;int min = 0;while(true){int mid = twoSort[(min+max)/2];if (f>mid){min=(min+max)/2+1;}else if(f<mid){max = (min+max)/2-1;}else{int fIndex = (min+max)/2;System.out.println(String.format("要查找的数据%s 在数组中的索引位置为: %s",f,fIndex));break;}}//Arrays自带二分查找法int F = 50;int indexF = Arrays.binarySearch(twoSort,F);System.out.println(String.format("要查找的数据%s 在数组中的索引位置为 %s",F,indexF));//二维数组，就是一维数组中嵌套一个数组,开发过程中使用较少//定义一个二维数组int[][] twoList = new int[][]{
{1,2,3},{4,5,6}};//二维数组遍历取值int val = twoList[1][2];System.out.println(val);for (int i = 0; i < twoList.length ; i++) {for (int j = 0; j <twoList[i].length ; j++) {System.out.print(twoList[i][j]);}}//快速遍历数组System.out.println("\n");int[] shu = new int[]{1,2,3,4,5,6};for (int i : shu) {System.out.print(i);}}
}