运算符和控制语句(外有获得输入的方法)

 1 import java.io.*;
 2     try{
 3         InputStreamReader isr= new InputStreamReader(System.in);
 4         BufferedReader br = new BufferedReader(isr);
 5         System.out.println("Plz input a number.");
 6         String a1= br.readLine();
 7         System.out.println("Plz input another number.");
 8         String a2 = br.readLine();
 9     }catch(Exception e){
10         e.printStackTrace();
11     }
12 Integer.parseInt(String)或者Float.parseFloat(String)