java构造函数错误（无法将int传递给构造函数）

Question

hi I'm new to java and I've been trying to pass an int form main method to a constructor in another class but there is some kind of error occurring. I can't understand what i did wrong.

class with the main method :

import java.util.Scanner;

public class _01 {


    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter your : ");
        String name = input.nextLine();
        int size = name.length();

        //System.out.println(size);


        _02 process = new _02(size);

    }

}

class that has the constructor:

public class _02 {

    int maxsize;
    int top;
    String arrayStack[];

    public void _02(int size) {

        maxsize = size;
        arrayStack = new String[maxsize];
        top = -1;
    }

    public void push(String... letters) {

        arrayStack[++top] = letters;

    }

    public String pop() {

        return arrayStack[top--];


    }
}

error message i'm getting :

Exception in thread "main" java.lang.Error: Unresolved compilation problem: The constructor _02(int) is undefined

at _01.main(_01.java:16)

Answer 1

That's because you are using void . Java thinks those are methods, not constructors. First of all stop giving your classes awful names. And then do this:

public class Whatever {
   private Integer size;
   public Whatever(Integer size) {
      this.size = size;
      System.out.println("I am a constructor");
   };
};

Example

public class Article {
    private String title;
    private String content;
    private String author;
    private DateTime publishDate;

    public Article(String title, String content, String author, DateTime publishDate) {
        this.title = title;
        this.content = content;
        this.author = author;
        this.publishDate = publishDate;
    };

};

Assume we are working together on a newspaper project. If I read your code and see _01 , it means nothing to me. If instead I see Article , with title , content , etc. I can immediately understand what you wrote and use it as I please.

If you come back to your own code two weeks later, you won't have a clue what you meant by _01 . As many developers, you won't remember. There's even a joke about it, done through a comment. It goes like this:

/**
 * At the time of this writing, only God and I knew what I was doing.
 * Now, only God knows.
 * /

Remeber, code is easy to write but very hard to read.

Answer 2

A constructor is a method without return type, so your constructor declaration should be:

public _02(int size)

A good practice will be to use follow java style guide, using names with capitalize letrer as class names, for example Two

Answer 3

A constructor doesn't have a return type. So remove void from public void _02(int size) if you want to use it as a constructor.

Your class naming is a little odd though...

Answer 4

从公共void _02（int size）{...}中删除“ void”