第七章数组课后总结

一.数组的基本结构 三种描述的形式

int [] num = new int[ ** ];int [] num ={ ********** };int [] num =new int [] {******************}

二. 使用java.util.Arrays

Arrays.sort()的作用: 对数组进行升序排列

三. 比较最大与最小 if (a[1]>max ){ max=a[1] ; } if (a[1]<min ){ min=a[1];} 四. 二维数值的表示 int[] [] scores=new int [] [] { { 90, 85, 92, 78, 54 }, { 76, 63,80 }, { 87 }};

五.课后作业 1.小结 输入数列 package ZYL;

import java.util.Scanner;

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

int[]scores = {8,4,2,1,23,344,12}; Scanner scanner = new Scanner(System.in); System.out.print("输入任何一个数字:"); int num = scanner.nextInt(); boolean Isbig = false; for(int i =0;i<7;i++){ if(num==scores[i]){ Isbig = true; break; } } if(Isbig){ System.out.println("输入正确"); } else{ System.out.println("不正确"); }}} 输入商品名称 package ZYL;

public class Demo2 { public static void main(String[] args) { String[] name = {“Nike背包”,“Adidas运动衫”,“李宁运动鞋”,“Kappa外套”,“361°腰包”};

System.out.println("被刺活动特价得商品有:"); for (int i = 0; i < name.length; i++) { System.out.println(name[i]); }

} } 3.购物金额结算 package ZYL;

import java.util.Scanner;

public class Demo3 { public static void main(String[] args) {

double[] money =new double[5]; Scanner scanner = new Scanner(System.in); System.out.println("请输入会员本月得消费记录"); for(int i =0;i<5;i++){ System.out.print("请输入第"+(i+1)+"笔购物金额:"); money[i] = scanner.nextDouble(); } System.out.println("序号"+" "+"金额"); System.out.println("1"+" "+money[0]); System.out.println("2"+" "+money[1]); System.out.println("3"+" "+money[2]); System.out.println("4"+" "+money[3]); System.out.println("5"+" "+money[4]); System.out.println("总金额"+" "+(money[0]+money[1]+money[2]+money[3]+money[4])); }

} 4.字符逆序输出 package ZYL;

import java.util.Arrays;

public class Demo4 { public static void main(String[] args) { String[] eng = { “a”, “c”, “u”, “b”, “e”, “p”, “f”, “z” }; System.out.print(“原字符序列:”); for (int i = 0; i < eng.length; i++) { System.out.print(eng[i]); } System.out.println(""); Arrays.sort(eng); System.out.print(“升序排序后:”); for (int i = 0; i < eng.length; i++) { System.out.print(eng[i]); } System.out.println(""); Arrays.sort(eng); System.out.print(“逆序输出为:”); for (int i = eng.length; i > 0; i–) { System.out.print(eng[i - 1]); }

}

} 5.向有序数列插入字符 package ZYL;

import java.util.Arrays;

public class Demo5 { public static void main(String[] args) {

String[] eng ={"a","b","c","e","f","p","u","z"}; System.out.print("原字符序列:"); for (int i = 0; i < eng.length; i++) { System.out.print(eng[i]+" "); } System.out.println(""); String a ="m"; System.out.println("插入一个原字符:"+a); System.out.println("插入字符得下标是:5"); String[] eng2=new String[eng.length+1]; for (int i = 0; i < eng2.length; i++) { if(i<eng.length){ eng2[i]=eng[i]; }else{ eng2[i]=a; } } Arrays.sort(eng2); System.out.print("插入后得字符顺序是:"); for (int i = 0; i < eng2.length; i++) { System.out.print(eng2[i]+" "); }

} } 6.求最小价格 package ZYL;

import java.util.Scanner;

public class Demo6 { public static void main(String[] args) { int[] money=new int[4]; Scanner scanner = new Scanner(System.in); System.out.println(“请输入4家店得价格”); for (int i = 0; i < 4; i++) { System.out.print(“第”+(i+1)+“家店得价格:”); money[i]= scanner.nextInt(); } int min =money[0]; for (int i = 0; i < money.length; i++) { if(money[i]<min){ min=money[i]; } } System.out.println(“最小值是:”+min);

}

} 7.教材第四章课后练习 1.package ZYL;

import java.util.Arrays;

public class Demo7 { public static void main(String[] args) {

int[] num= new int[]{1 , 3 , -1 , 5 , -2}; System.out.print("原数组:"); for (int i = 0; i < num.length; i++) { System.out.print(num[i]+" "); } System.out.println(" "); Arrays.sort(num); System.out.print("排序后得数组是:"); for (int i = 0; i < num.length; i++) { System.out.print(num[i]+" "); }

} } 2.package ZYL;

import java.util.Arrays; import java.util.Scanner;

public class Demo9 { public static void main(String[] args) { String[] str=new String[5]; Scanner scanner = new Scanner(System.in); System.out.println(“输入5句话:”);

for (int i = 0; i < str.length; i++) { System.out.print("第"+(i+1)+"句话:"); str[i]=scanner.next(); } Arrays.sort(str); System.out.println("逆序输出5句话:"); for (int i =str.length ; i>0; i--) { System.out.println(str[i-1]); } }

} 2.package ZYL;

import java.util.Scanner;

public class Demo8 { public static void main(String[] args) { int[] num = new int[10]; int a = 0; int b = 0; int c = 0;

Scanner scanner = new Scanner(System.in); System.out.println("请输入10个数:"); for (int i = 0; i < num.length; i++) { num[i] = scanner.nextInt(); } System.out.print("输入的10位数为:"); for (int i = 0; i < num.length; i++) { System.out.print(num[i] + " "); } System.out.println(" "); for (int i = 0; i < num.length; i++) { if (num[i] == 1) { a++;} if (num[i] == 2) { b++;} if (num[i] == 3) { c++;} } System.out.println("数字1的个数为:" + a); System.out.println("数字2的个数为:" + b); System.out.println("数字3的个数为:" + c); System.out.println("非法数字的个数为:" + (10-a-b-c));

} }