题目:
1. 给定一个字符串,判断该字符串中是否包含某个子串.如果包含,求出子串的所有出现位置.
如:"abcbcbabcb34bcbd"中,"bcb"子串的出现位置为: 1,7,12.字符串和子串均由用户输入
2.给定一个长度,随机产生一个该长度的字符串,由大写,小写字母以及数字组成
Java中随机数的生成:
java.util.Random r = new java.util.Random();
int a = r.nextInt(100): a 0-99的随机数
3.给定一个由数字组成的字符串,如:"1239586838923173478943890234092",统计
出每个数字出现的次数
答案如下:
package Chp10; import java.util.HashMap; import java.util.Map; import java.util.Random; import java.util.Scanner; import java.util.Set; public class TestString2 { public static void Method_One() { Scanner s = new Scanner(System.in); System.out.println("请输入一个父串"); String str = s.next(); System.out.println("请输入一个子串"); String str1 = s.next(); int stat = 0; while (true) { int i = str.indexOf(str1,stat); if (i==-1) { break; } System.out.println(i); stat = i+str1.length(); } } public static void Method_Two() { System.out.println("请输入一个长度"); Scanner s = new Scanner(System.in); int n = s.nextInt(); char[] cs = new char[n]; Random random = new Random(); for (int i = 0; i < n; i++) { int a = random.nextInt(62); if(a>=0 && a<=25) { a+=65; } else if (a>25 && a<=51) { // 97 - 26 = 71 a+=71; } else { // 52-48 = 4 a-=4; } cs[i] = (char)a; } System.out.println(cs); } public static void Method_Three() { Scanner scanner = new Scanner(System.in); String string = scanner.next(); int[] c = new int[10]; for (int i = 0; i < string.length(); i++) { char c1 = string.charAt(i); //48-57 int a = c1-48; // 类型转换 c[a]++; } for (int i = 0; i < c.length; i++) { System.out.println(i+" 出现的次数: "+c[i]); } System.out.println("=========方法二=========="); String s = "12548954231351486214894562"; char[] ch = s.toCharArray(); Map<Character, Integer> map = new HashMap<Character, Integer>(); Set<Character> set = map.keySet(); for (int i = 0; i < ch.length; i++) { if (set.contains(ch[i])) // 判断map中已经有的char值 { map.put(ch[i], map.get(ch[i])+1); } else { map.put(ch[i], 1); // 第一次放入map中 } } Set<Character> set2 = map.keySet(); for (Character character : set2) { System.out.println(character+"=========="+map.get(character)); } } public static void main(String[] args) { System.out.println("第一题如下:"); Method_One(); System.out.println("第二题如下:"); Method_Two(); System.out.println("第三题如下:"); Method_Three(); } }
时间: 2024-10-06 00:29:32