Java基础 3.29

1.数组的相关注意事项

错误示范一

String strs[] = new String[2]{"a", "b"};

正确示范一

String strs[] = new String[]{"a", "b"};

 让JVM自己判断有几个数据，无需再其中写明有几组数据

错误示范二

String strs[] = new String{"a", "b"};

正确示范二

String strs[] = {"a", "b"};

2.数组相关练习

/*
已知有个升序数组，要求插入一个元素，该数组顺序依然是升序的
*/
import java.util.Scanner;
public class ArrayHomework01 {
	public static void main(String[] args) {
		Scanner myScanner = new Scanner(System.in);
		int arr[] = {10, 12, 45, 90};
		int arr2[] = new int[arr.length + 1];
		System.out.println("请输入你要添加的数字");
		int addNum = myScanner.nextInt();
		for (int j = 0; j < arr.length; j++) {//直接扩容
			arr2[j] = arr[j];
			arr2[j+1] = addNum;
		}
		arr = arr2;//将原数组地址定位到扩容后的数组的地址
		int temp = 0;
		for (int i = 0; i < arr.length; i++) {//再用冒泡算法重新排列
			int times = arr.length - 1;
			for (int j = 0; j < times; j++) {
				if (arr[j] > arr[j+1]) {
					temp = arr[j];
					arr[j] = arr[j+1];
					arr[j+1] = temp;
				}
			}
		}
		
		for (int i = 0; i < arr.length; i++) {//输出排列完后的数组
			System.out.print(arr[i] + " ");
		}
		
	}
}

//解法2
public class ArrayHomework01 {
	public static void main(String[] args) {
		int arr[] = {10, 12, 45, 90};
		int insertNum = 23;
		int index = -1;
		for (int i = 0; i < arr.length; i++) {
			if (insertNum <= arr[i]) {
				index = i;
				break;
			} 
		} 

		if (index == -1) {
			index = arr.length;
		}
		//System.out.print(index);
		int arrNew[] = new int[arr.length + 1];

		for (int i = 0, j = 0; i < arrNew.length; i++) {
			if (i != index) {
				arrNew[i] = arr[j];
				j++;
			} else {
				arrNew[i] = insertNum;
			}
		}
		arr = arrNew;
		for (int i = 0; i < arr.length; i++) {
			System.out.print(arr[i] + " ");
		}
	}
}