使用另一个类的变量 [英] use variable from another class

问题描述

我有两个类。我想使用第二个类中的第一个类中的 english 和 french （类Question）。

I have two classes. I want to use english and french from the first class in the second class (class Question). Please help me to fix that code because it shows me an error.

代码块：

package josephtraduire;

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

public class FileParser implements IParser{

    @Override
    public void parseFile () throws IOException{
        String french="";
        String english="";

        try( BufferedReader br = new BufferedReader(new FileReader("C:\\Users\\User\\Desktop\\text.txt"))){
            String line;        
            while ((line = br.readLine())!=null){
                    String[] pair = line.split(";");
                    french=(pair[0]);
                    english=(pair[1]);
            }
        }        
    }            

}

和

package josephtraduire;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Date;
import java.util.Scanner;

public class Question extends FileParser {

String mot ;
String reponse ;
String name;
int nb;
int nbquest ;
String traduction;

Question (String name , int nb){
    this.name=name;
    this.nb=nb;
}

Question() throws IOException{

    InputStreamReader isr = new InputStreamReader(System.in); 
    BufferedReader in = new BufferedReader(isr); 
    { 
        System.out.println("Entrer votre nom "); 
        String nom = in.readLine(); 
        name=nom;
    }    

    do {
        System.out.println("Rentrez le nombre de question :    ( max 20 )");
        Scanner nombrequest = new Scanner(System.in);
        nbquest = nombrequest.nextInt();
        nb=nbquest;
    }  while ( nbquest>20 ||nbquest<=0);

}

public void Play () throws IOException{

    int i=0;   
    boolean bool=true;    
    int score=0;
    String continuer; 
    Date maDate = new Date();
    String a = maDate.toString() ;

    while (i<nbquest && bool) {
        InputStreamReader isr = new InputStreamReader(System.in); 
        BufferedReader in = new BufferedReader(isr); 

        System.out.println("donner la traduction de "+french);
        String reponseee  = in.readLine();     
        traduction=reponseee;  

        if(bool=true ){ 
            if(traduction.equals(english)){
                score++;
                System.out.println("Bravo! Bonne reponse");
            }else{
                System.out.println("Mauvaise reponse");
            }
        }

推荐答案

I我们将忽略源代码并且一般地回答这个问题。您可以直接或使用getter访问对象的实例变量。我将在这个例子中使用getters。

I'm going to ignore the source code and answer this in general terms. You can access the instance variables of an object, either directly or using getters. I will use getters in this example.

实例变量 - 只要类生活，它们是
类的主体，但不在任何方法或
构造函数

Instance variables - live for as long as the class lives, they are declared within the body of the class but not within any method or constructor

方法变量 - 只要方法生效，不再是，通常
做一些工作，然后走了，他们在一个
方法/构造函数中声明

Method variables - live for as long as the method and no longer, usually do some job and then are gone, they are declared within a method/constructor

public class ClassThatWantsFields {

    public String combineFields(ClassWithFields classWithFields){
        //if I have access to the object classWithFields then I have access to its
        //public methods (and possibly also protected and default access; but this is outside the scope of this question)
        return classWithFields.getEnglish()+classWithFields.getFrench();
    }

    public static void main(String[] args){
        ClassWithFields classWithFields=new ClassWithFields();
        ClassThatWantsFields classThatWantsFields=new ClassThatWantsFields();

        System.out.println(classThatWantsFields.combineFields(classWithFields));
    }

}

public class ClassWithFields {
    private String English; //these are instance variables, they live for as long as the object lives
    private String French;

    private String preservedMayFly; 

    public ClassWithFields(){
        English="A language called English";
        French="A language called French";

        //mayfly is a method variable, it will be gone once the constructor 
        //exits, anything you want to keep for the life of the object should 
        //NOT be a method variable
        String mayfly="I won't live long";

        //preservedMayFly is an instance variable and will live as long as
        //the object
        preservedMayFly=mayfly+"but I can be used within the method"
    }

    public String getEnglish() {
        return English;
    }

    public String getFrench() {
        return French;
    }



}

这篇关于使用另一个类的变量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！