java的学习笔记

主函数

public static void main(String[]args){

System.out.println(“”);

System.err.println(“”);

}

输出输入

import java.util.Scanner;

Scanner scanner=new Scanner(System.in);

String line =scanner.next();

输出流
PrintStream out = System.out;

PrintStream ps=new PrintStream("log.txt");

            System.setOut(ps);

            System.setOut(out);

出错

  try{

  }catch (FileNotFoundException e) {

           e.printStackTrace();

       }

加密

public class Examplemiyao {

  public static void main(String[] args) {

  System.out.println("请输入一个英文字符串或解密字符串");

  Scanner scan = new Scanner(System.in);

  String password = scan.nextLine();

  char[] array = password.toCharArray();

  for (int i = 0; i < array.length; i++) {

    array[i] =  array[i];

            //array[i] = (char) (array[i] ^ 20000);

        }

        System.out.println("加密或解密结果如下：");

        System.err.println(new String(array));

    }

}

判断奇偶数

long number = scan.nextLong();

String check = (number % 2 == 0) ? "这个数字是:偶数" : "这个数字是：奇数";