JAVA学习笔记10_Java语言基础（Ｓｃａｎｎｅｒ类和Ｓｔｒｉｎｇ类）

public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		//int i = sc.nextInt();//键盘录入整数
		//System.out.println(i);
		if (sc.hasNextInt()){
			int i = sc.nextInt();
			System.out.println(i);
		}else{
			System.out.println("输入的类型错误");
		}
		
	}

//同一个对象先获取int值，在获取String值的代码，但是会出现问题

public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.println("请输入第一个整数");
		int i = sc.nextInt(); 
		System.out.println("请输入第一个字符串");
		String line = sc.nextLine();
		System.out.println("i="+i+"  line="+line);	
	}

１．ｔｒｕｅ　　ｔｒｕｅ

２．２个

３．ｆａｌｓｅ　　　ｔｒｕｅ

４．ｔｒｕｅ　　　ｔｒｕｅ

５．ｆａｌｓｅ　　　ｔｒｕｅ

}

package com.heima.scanner;
import java.util.Scanner;
public class Demo2_Scanner {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		for (int i=1; i <=3 ; i++) {
			System.out.println("请输入用户名：");
			String userName = sc.nextLine();
			System.out.println("请输入密码：");
			String password = sc.nextLine();
			//如果是字符串常量和字符串变量比较，通常都是字符串常量调用方法，将变量作为参数传递，防止空指针异常
			if("admin".equals(userName)&&"admin".equals(password)){
				System.out.println("欢迎"+userName+"登录");
				break;
			}else{
				if (i==3) {
					System.out.println("输入错误已达上限");
				}
				else{
					System.out.println("录入错误，您还有"+(3-i)+"次机会");
				}
			}
		}
		
	}

public static void main(String[] args) {
		String s = "heima";
		for (int i = 0; i < s.length(); i++) {
			char c = s.charAt(i);／／获取按位置索引的字符
			System.out.print(c);
		}

	public static void main(String[] args) {
		String s = "ABCDEabcd123456!@#$%^";
		int big=0;
		int small=0;
		int num = 0;
		int other=0;
		for (int i = 0; i < s.length(); i++) {
			char c = s.charAt(i);
			if (c>='A'&&c<='Z') {
				big++;
			}
			else if (c>='a'&&c<='z') {
				small++;
			}else if (c >= '0'&&c<='9') {
				num++;
			}
			else{
				other++;
			}
		}
		System.out.println(s+"中大写字母有"+big+"个，"+"小写字母有"+small+"个，"+"数字有"+num+"个，"+"其他有"+other+"个");
		
	}

public static void main(String[] args) {
		String s = "woaiHEimAniaima";
		String s2 = s.substring(0,1).toUpperCase().concat(s.substring(1).toLowerCase());
		System.out.println(s2);
	}

public static void main(String[] args) {
		int[] arr = {1,2,3};
		String s = "[";
		for (int i = 0; i < arr.length; i++) {
			if (i==arr.length-1) {
				s = s+arr[i]+"]";
			}else{
				s= s +arr[i]+",";
			}
		}
		System.out.println(s);
	}

／／字符串反转

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String line = sc.nextLine();
    char[] arr = line.toCharArray();//转换成字符数组
    String s ="";
    for (int i = arr.length-1; i >=0; i--) {
        s = s+arr[i];
    }    
    System.out.println(s);
}

public static void main(String[] args) {
		//定义大串
		String max = "woaiheima,heimabutongyubaima";
		//定义小串
		String min = "heima";
		
		//定义计数器变量
		int count = 0;
		//定义索引
		int index= 0;
		//定义循环，判断小串是否在大串中出现
		while ((index = max.indexOf(min))!=-1) {
			count++;
			max = max.substring(index+min.length());
		}
		System.out.println(count);
	}