普通的就用Scanner就可以，而如果是大型字符串就是用io输入流，io的弊端就是只能输入字符

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
 public static void main(String[] args) throws IOException {
  InputStreamReader r=new InputStreamReader(System.in);                         
  BufferedReader br = new BufferedReader(r);
  br.readLine();
  br.read();
  
 }

}