如何访问另一个类的函数中一个类的变量？ [英] How do I access a variable of one class in the function of another class?

问题描述

我有一个类主（它有 public static void main（String [] args））和另一个类 MyDocument 。

在Main类中有一个变量 text ，我想从函数 alphabetOccurrence （），显示在 MyDocument 类中。我如何做到这一点？我不想使用它作为一个静态变量。并且任何更改只能在函数中完成，其余的代码应该保持不变。

  import java.util。*; 
 
 class Main {
 public static void main（String [] args）{
 MyDocument document = null; 
 String text; 
 text =早上好，早上好亚历山大，你的国家有多少人？他们都有大房子，大车？他们都吃好食物？ 
 char letter ='d'; 
 document = new MyDocument（）; 
 document.setDocumentText（text）; 
 System.out.println（Letter+ letter +has occured
 + document.alphabetOccurrence（letter）+times）; 
} 
} 
 
 class MyDocument {
 private ArrayList< Character> document = new ArrayList（）; 
 
 public MyDocument（）{
} 
 
 void setDocumentText（String s）{
 for（int i = 0; i  document.add（s.charAt（i））; 
} 
 
 ArrayList getDocumentText（）{
 return this.document; 
} 
 
 public int alphabetOccurrence（char letter）{
 //在这里使用文本变量.. 
} 
} 
   
 
解决方案
您应该更改 MyDocument 类添加新的 String 字段以保存文本：
  import java.util.ArrayList; 
 
 class MyDocument {
 
 private String text; 
 private ArrayList< Character> document = new ArrayList（）; 
 
 public MyDocument（）{
} 
 
 void setDocumentText（String s）{
 this.text = text; 
 for（int i = 0; i  document.add（s.charAt（i））; 
} 
 
 ArrayList< Character> getDocumentText（）{
 return this.document; 
} 
 
 public int alphabetOccurrence（char letter）{
 
 this.text; // do something 
 
} 
} 
  
 
I'm having a class Main (which has public static void main(String []args))and another class MyDocument.

There is a variable text present in the Main class which I want to access from a function alphabetOccurrence() present in the MyDocument class. How do I do this? I don't want to use it as a static variable. And any changes can be done only in the function, rest of the code should be untouched.
import java.util.*;

class Main {
    public static void main(String[] args) {
        MyDocument document = null;
        String text;
        text = "good morning. Good morning Alexander. How many people are there in your country? Do all of them have big houses, big cars? Do all of them eat good food?";
        char letter = 'd';
        document = new MyDocument();
        document.setDocumentText(text);
        System.out.println("Letter " + letter + " has occured "
                + document.alphabetOccurrence(letter) + " times");
    }
}

class MyDocument {
    private ArrayList<Character> document = new ArrayList();

    public MyDocument() {
    }

    void setDocumentText(String s) {
        for (int i = 0; i < s.length(); i++)
            document.add(s.charAt(i));
    }

    ArrayList getDocumentText() {
        return this.document;
    }

    public int alphabetOccurrence(char letter) {
        // use text variable here..
    }
}

解决方案
You should change your MyDocument class  to add new String field to hold text:
import java.util.ArrayList;

class MyDocument {

    private String text;
    private ArrayList<Character> document = new ArrayList();

    public MyDocument() {
    }

    void setDocumentText(String s) {
        this.text = text;
        for (int i = 0; i < s.length(); i++)
            document.add(s.charAt(i));
    }

    ArrayList<Character> getDocumentText() {
        return this.document;
    }

    public int alphabetOccurrence(char letter) {

        this.text; //do something

    }
}


                        
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