How to input from the keyboard in java (with code)

1. Java does not have a powerful function like scanf in C. Most of them are defined by input and output stream objects. Commonly used classes include BufferedReader and Scanner.

Recommended java video tutorials: java

Example program: Video tutorial

1. Use Scanner to read integer or float data from the keyboard

//import java.io.*;
import java.util.*;
public class InputTest{
public static void main(String[] args){
  Scanner in = new Scanner(System.in);    //Scanner类
  System.out.println("Please input a float number:");
  float a = in.nextFloat();    //接收float数据
  System.out.println("Please input a string: ");    //这里试了一下输入String数据，但中间有空格就不能显示，Scanner类还不具有这功能
  Scanner str = new Scanner(System.in);
  System.out.println("The string is :" + str.next());
  System.out.println("The float number is: " + a);
  for(int i = 0;i < 4;i++){
   System.out.println("Please input a int number: ");   //for循环接收int型数据
   int b = in.nextInt();
   System.out.println("The int number is: " + b);
  }
}
}

2. Use BufferedReader to read strings from the keyboard and write them into the file abc.txt

import java.io.*;
public class InputTest{
public static void main(String[] args) throws IOException{
  BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
  BufferedWriter buf2 = new BufferedWriter(new FileWriter("abx.txt"));
  String str = buf.readLine();
  while(!str.equals("exit")){
   buf2.write(str);
   buf2.newLine();
   str = buf.readLine();
  }
  buf.close();
  buf2.close();
}
}

The BufferedReader class is located in the java.io package, so to use this class, you must Introduce the java.io package: import java.io.BufferedReader.

Instructions on the JDK1.5 Scanner class

Scanner is a new class added in SDK1.5, but it can be created using this class An object.

Scanner reader=new Scanner(System.in);

Then the reader object calls the following methods (functions) to read various data types entered by the user on the command line:

next.Byte(),nextDouble(),nextFloat,nextInt(),nextLine(),nextLong(),nextShot()

The input line using the nextLine() method may contain spaces. If what is read is a word, you can call the .next() method

For more java related articles, please pay attention to the java basic tutorial column.

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