2021-10-08

java中对于数组的应用：

import java.util.Scanner;

public class arrChange{
	public static void main(String[] args) {


		

		int[] arr = new int[0];
		mytools tool = new mytools();
		
		do{
			Scanner myScanner = new Scanner(System.in);
			System.out.println("n请输入数字进行选择操作:");
			System.out.println("1、定义初始数组n" + "2、添加元素n"  + "3、升序排序n" + "4、降序升序n");
			int systemInInt = myScanner.nextInt();
			switch(systemInInt){
				case 1:
					arr = tool.arrDefine(arr);
					tool.printArr(arr);
					break;
				case 2:
					arr = tool.arrAdd(arr);
					tool.printArr(arr);
					break;
				case 3:
					arr = tool.arrSortByUp(arr);
					break;
				case 4:
					arr = tool.arrSortByDown(arr);
					break;
			}
		}while(true);
		// arr = tool.arrDefine(arr);
		// tool.arrAdd(arr);
		// tool.arrSortByUp(arr);
		// tool.arrSortByDown(arr);
	}
}




class mytools{
	public  int[] arrSortByUp(int[] arr){
		int temp = 0;
		for (int j = 0;j < arr.length - 1;j++ ) {
			for (int i = 0;i < arr.length -1 ; i++) {//内部循环也是length - 1，外部也是
				if (arr[i] > arr[i+1]) {
					temp = arr[i];
					arr[i] = arr[i+1];
					arr[i+1] = temp;
				}
			}
		}
		System.out.println("进行升序之后的数组为：");
		for (int i = 0;i < arr.length ;i++ ){
				System.out.print(arr[i] + "t");
			}
		return arr;
	}

	public  int[] arrSortByDown(int[] arr){
		int temp = 0;
		for (int j = 0;j < arr.length - 1;j++ ) {
			for (int i = 0;i < arr.length -1 ; i++) {//内部循环也是length - 1，外部也是
				if (arr[i] < arr[i+1]) {
					temp = arr[i];
					arr[i] = arr[i+1];
					arr[i+1] = temp;
				}
			}
		}
		System.out.println("进行升序之后的数组为：");
		for (int i = 0;i < arr.length ;i++ ){
				System.out.print(arr[i] + "t");
			}
		return arr;
	}

	public int[] arrAdd(int[] arr){
				//  动态扩容数组arr
				// 1.复制原来的数组
				// 2.在基础上增加数组新元素
				// 3.将原来数组指向新数组
		do{
			char flag;
			int[] arrAdd = new int[arr.length + 1];
			for (int i = 0;i < arr.length ;i++ ) {
				arrAdd[i] = arr[i];
			}

			System.out.println("请输入你要添加的元素的值");
			Scanner myScanner = new Scanner(System.in);
			int addInt = myScanner.nextInt();
			arrAdd[arrAdd.length - 1] = addInt;
			arr = arrAdd; 

			System.out.println("扩容后的数组为：===================");
			for (int i = 0;i < arr.length ;i++ ) {
				System.out.print(arr[i] + "t");
			}

			System.out.println("n" + "请问是否还需要继续添加？y/n");
			flag = myScanner.next().charAt(0);
			if ( flag == 'y' ) {
				continue;
			}else if(flag == 'n'){
				break;
			}else{
				System.out.println("输入错误，已经推出程序！");
				break;
			}
		}while(true);
		return arr;
	}

	public int[] arrDefine(int[] arr){
		do{
			char flag;
			int[] arrAdd = new int[arr.length + 1];
			for (int i = 0;i < arr.length ;i++ ) {
				arrAdd[i] = arr[i];
			}

			System.out.println("请输入你要定义的元素的值");
			Scanner myScanner = new Scanner(System.in);
			int addInt = myScanner.nextInt();
			arrAdd[arrAdd.length - 1] = addInt;
			arr = arrAdd; 

			System.out.println("定义的数组为：===================");
			for (int i = 0;i < arr.length ;i++ ) {
				System.out.print(arr[i] + "t");
			}

			System.out.println("n" + "请问是否还需要继续添加？y/n");
			flag = myScanner.next().charAt(0);
			if ( flag == 'y' ) {
				continue;
			}else if(flag == 'n'){
				break;
			}else{
				System.out.println("输入错误，已经推出程序！");
				break;
			}
		}while(true);
		return arr;
	}
	public void printArr(int[] arr){
		System.out.println("定义的数组为：===================");
		for (int i = 0;i < arr.length ;i++ ) {
				System.out.print(arr[i] + "t");
			}
	}
}