Question for when the String is blank.

Hello!

If you enter a space when you receive the string (variable name word), you want to output true, false, depending on whether this string is blank or not.

If there is a space in the String, why can't I do branching in if(word.equals(")) System.out.println("blank");?

The source code we tested is as follows.

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

public class Demo {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String word = br.readLine().trim();

        if(word.equals("  ")) {
            System.out.println ("blank");
        }
        else if(word.trim().length()==0) {
            System.out.println ("Trim");
        }
        else if(word.equals(null)) {
            System.out.println("null");
        }
        else {
            System.out.println ("string: "+word+"string length:"+word.length()));
        }
    }
}

Thank you!

java string

2022-09-21 11:49

2 Answers

String word = br.readLine().trim();

from trim () Removes a trim because it is to remove a space.

String word = br.readLine();

If you put in the space twice and type enter, it will be judged as blank.

2022-09-21 11:49

If it were me, I'd revise it like this.

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

public class Demo {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        Remove String word = br.readLine(); //.trim() and check trim below

        Method for verifying that if(word.isBlank()) { //word consists of only blank characters such as white space, tab, etc
            System.out.println ("blank");
        }
        else if(word.trim().length()!=word.length()) { // true if removing a space before and after is different from the original string length
            System.out.println ("Trim");
        }
//        else if(word.equals(null)) { //This if statement is meaningless. There is no null value because you assigned a string with br.readLine().
//            //            System.out.println("null");
//        }
        else {
            System.out.println ("string: "+word+"string length:"+word.length()));
        }
    }
}

2022-09-21 11:49

If you have any answers or tips

Popular Tags

python x 4647

android x 1593

java x 1494

javascript x 1427

c x 927

c++ x 878

ruby-on-rails x 696

php x 692

python3 x 685

html x 656