When doing online programming problems, you need to know the data input format. This can have a better grasp of data processing, do not need to put too much time on this, focus on the main algorithm logic can be. Here’s a summary for the written test.

1. Input from the terminal

How to use the Scanner class:

Scanner scanner = new Scanner(System.in);
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Gets an input stream from the terminal, which is passed in as a parameter when Scanner initializes the object.

The Scanner class has several important methods:

Next method (read a character)

  • 1, must read valid characters before you can end the input (if nothing is input, the program does not end)
  • 2. The next method automatically removes whitespace encountered before entering valid characters. Only after a valid character is entered will the following input whitespace be used as a delimiter or terminator.
  • The next method completes the eng to get a string with a space.
   public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){ String next = sc.next(); System.out.println(next); }}Copy the code

NextLine method (reads a string)

  • 1. The nextLine() method ends with Enter, which means that it returns all characters up to Enter.
  • 2. You can get whitespace.
   public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextLine()){ String next = sc.nextLine(); System.out.println(next); }}Copy the code

nextInt

Read an integer. Sometimes you can get an integer directly from a terminal without having to convert a String to an int. This reduces the running time of the program.

2. The String and Char

String toChar [] : toCharArray()

Scanner sc = new Scanner(System.in);
String line = sc.nextLine();
char[] chars = line.toCharArray();
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String to single insert character: use charAt()

 Scanner sc = new Scanner(System.in);
 String line = sc.nextLine();
 char charAt = line.charAt(2);
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3. The String and int

Int to String: valueOf()

int n = 10;
String s = String.valueOf(10);
System.out.println(s);
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String to int: use integer.parseint (s);

  Scanner sc = new Scanner(System.in);
  String line = sc.nextLine();
  int i = Integer.parseInt(line);
  System.out.println(i);
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4. Input format

Such as:

5.15 2.10
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import java.util.Scanner;
/ * * *@author [email protected] 2018/8/24 19:27
 */
public class ScannerTest {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String line = sc.nextLine();
        String[] split = line.split("");
        for (int i = 0; i < split.length; i++) {
            String s = split[i];
            int i1 = Integer.parseInt(s.split(",") [0]);
            int i2 = Integer.parseInt(s.split(",") [1]);
            System.out.println(i1+""+i2); }}}Copy the code

Start to do online pen test!