数组
用来存放一组数据的数据结构
1.创建数组(3种方法)
l int[] a = new int[5];
n 新建int[]数组，长度5
n 5个位置存默认值0
n 数组的地址，存到变量a
l int[] a = {5,3,7,8,6,3,1,6};
l 为一个存在的数组变量赋值，用大括号直接初始化数组
a = new int[]{5,3,7,3};
数组的长度属性
(1)A.length
(2)数组一旦创建长度不可变
(3)允许0长度的数组
数组的遍历
从头到尾,依次访问数组的每个位置
for(int i=0; i<a.length; i++) {
a[i]
}
package day0405;
import java.util.Arrays;
public class Test1 {
public static void main(String[] args) {
f1();
f2();
f3();
}
private static void f3() {
int[] ints = new int[10];
for (int i =0;i<ints.length;i++)
{
ints[i] = i;
}
System.out.println(Arrays.toString(ints));
}
private static void f2() {
int[] a = {1,2,3,4,5,6};
System.out.println(Arrays.toString(a));
a = new int[]{6,5,4,3,2,1};
System.out.println(Arrays.toString(a));
}
private static void f1() {
char[] a = new char[5];
a[0] = 'h';
a[1] = 'e';
a[2] = 'l';
a[3] = 'l';
a[4] = 'o';
System.out.println(Arrays.toString(a));
}
}
商品录入查询
package day0406;
import java.util.Scanner;
public class Test1 {
static String[] names = {"商品1","商品2","商品3","商品4","商品5"};
static Double[] price = {10.55,20.66,30.77,40.88,50.99};
static int[] nums = {1,2,3,4,5};
public static void main(String[] args) {
outer:
while(true)
{
menu();
int i = new Scanner(System.in).nextInt();
switch (i)
{
case 1: f1();break;
case 2: f2();break;
case 3: f3();break;
case 4: f4();break;
case 5: break outer;
}
}
}
private static void menu()
{
System.out.println("1:商品列表");
System.out.println("2:商品录入");
System.out.println("3:商品查询");
System.out.println("4:统计信息");
System.out.println("5:退出");
System.out.print("选择:");
}
private static void f4()
{
double totalPrice = 0;
double allPrice = 0;
double maxTotalPrice = 0;
double maxPrice = 0;
for (int i=0;i<names.length;i++)
{
totalPrice += price[i]*nums[i];
allPrice += price[i];
if(price[i] > maxPrice) maxPrice = price[i];
if(price[i]*nums[i] > maxTotalPrice) maxTotalPrice = price[i]*nums[i];
}
System.out.println("总价:"+totalPrice);
System.out.println("单价均价:"+allPrice/names.length);
System.out.println("最高总价:"+maxTotalPrice);
System.out.println("最高单价:"+maxPrice);
}
private static void f3()
{
System.out.print("输入要查询的商品名:");
String s = new Scanner(System.in).nextLine();
for (int i=0;i<names.length;i++)
{
if(s.equals(names[i]))
{
String n = names[i];
double p = price[i];
int b = nums[i];
System.out.println((i+1)+":名称:"+n+",价格:"+p+",数量:"+b);
return;
}
}
System.out.println("找不到商品");
}
private static void f2()
{
for (int i=0;i<names.length;i++)
{
System.out.println("录入第"+(i+1)+"件商品:");
System.out.print("名称:");
names[i] = new Scanner(System.in).nextLine();
System.out.print("价格:");
price[i] = new Scanner(System.in).nextDouble();
System.out.print("数量:");
nums[i] = new Scanner(System.in).nextInt();
}
f1();
}
private static void f1()
{
for(int i=0;i<names.length;i++)
{
String n = names[i];
double p = price[i];
int b = nums[i];
System.out.println((i+1)+":名称:"+n+",价格:"+p+",数量:"+b);
}
}
}