数组的排序

eg1

import java.util.Arrays;

public class Fur05 {
	public static void main(String[] args) {
		// int[] num= {1,67,18,28,5,6,26,8,9,34};
		int[] num1 = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
		int target = 2;
		// 快速排序法
//	Arrays.sort(num);
//	System.out.println(Arrays.toString(num));
		// 二分法
		int index = Arrays.binarySearch(num1, target);
		System.out.println(Arrays.toString(num1));
	}
}

eg2

import java.util.Arrays;
public class Fur06 {
	public static void main(String[] args) {
		// 无序数组
		int[] num = {2, 7, 1, 14, 8, 12, 3, 10 };
		System.out.println(Arrays.toString(num));
		// n个数字来排序
		// 俩俩比较靠前
		// 总共比较n-1轮
		// 比较n-1轮
		int count=0;
		for (int i = 0, n = num.length; i < num.length - 1; i++) {
			//是否已经处于”有序“状态
			//true代表有序
			//false代表无序
			boolean isSorted=true;
			//每轮比较n-1-i
			for (int k = 0; k < n - 1 - i; k++) {
				count++;
				//相邻比较
				if (num[k] > num[k + 1]) {
					//交换
					num[k] = num[k] ^ num[k + 1];
					num[k + 1] = num[k] ^ num[k + 1];
					num[k] = num[k] ^ num[k + 1];
					isSorted=false;
				}
			}

			if(isSorted) {
				break;
			}
		}
		System.out.println("比较了："+count+"次");
		System.out.println(Arrays.toString(num));
	}
}

eg3

import java.util.Arrays;

public class Fur07 {
	public static void main(String[] args) {
		String[] name= {"tina","alice","bill","mary","divid","helen",};
		System.out.println(Arrays.toString(name));
		//数组相邻元素比较
		//a.compareTo()
		//ab结果是正数
		//a=b结果是零
		for(int i=0,n=name.length;i0) {
					String temp=name[k];
					name[k]=name[k+1];
					name[k+1]=temp;
				}
			}
		}
		System.out.println(Arrays.toString(name));
	}
}

eg4

import java.util.Arrays;

public class Fur08 {
	public static void main(String[] args) {
		int[] num= {1,2,3,4,5,6,7,8,9};
		//顺序
		for(int i=0;i=0;i--) {
			System.out.println(num[i]+"\t");
		}
		System.out.println();
		//foreach
		//只能顺序遍历
		//不能修改数组
		for(int n:num) {
			n=n*10;
			System.out.println(n+"\t");
		}
		System.out.println(Arrays.toString(num));
	}
}