Java：在这种情况下如何解析字符串？

Question

So I have created a simple class in Java like this:

public class Book {
    private String author;
    private String title;

    public Book (String author, String title) {
        this.author = author;
        this.title = title;
    }
}

public void checkInfo     

Is there a way to parse a string (property) in order to get Book properties like this, instead of doing bookA.title ?

Book bookA = new Book("George Orwell","Animal Farm")

String property = "title";
System.out.print(bookA.property);

Thanks in adance!

Answer 1

If you really want to access many properties as String , I suggest you using a Map<String, String> like this :

public class Book
{
    private Map<String, String> properties = new HashMap();

    public void setProperty(String name, String value)
    {
        properties.set(name,string);
    }

    public String getProperty(String name)
    {
        return properties.get(name);
    }
}

Now you can use like this :

Book book = new Book();

book.setProperty("title","Animal Farm");
book.setProperty("author","George Orwell");

System.out.println("Book: " + book.getProperty("title") + " by " + book.getProperty("author"))

Answer 2

You've created your Book as an object.
So, treat it like an object and add getters and setters.

In this case, that would be a method, getTitle() and a separate method getAuthor() .
For more information on getters and setters, see the responses to this previous StackOverflow post

Answer 3

You can use reflection:

 Field f = bookA.getClass().getDeclaredField("title");
 f.setAccessible(true);
 String title = (String) f.get(bookA);
 System.out.println(title);

Answer 4

First of all, your code won't work because title is private. Second, I have no idea why you set Book class as static. Last, this (Java) is object oriented programming, so treat it like an object.

When you create a class you also add Getters & Setters to access the information inside. The code would look like this:

Class :

public class Book {
    private String author;
    private String title;

    public Book (String author, String title) {
        this.author = author;
        this.title = title;
    }
}

public String getTitle(){
    return this.title;
}

public String getAuthor(){
    return this.author;
}

Accessing the data :

Book bookA = new Book("George Orwell","Animal Farm")

System.out.print("Book: " + bookA.getTitle() + " by " + bookA.getAuthor());

This would return :

Book: Animal Farm by George Orwell

Answer 5

If you see these few lines from your code:

private String author;  // both are private variables
private String title;  

Here author and title both are private String . So you can't access these properties outside of the class.

So, you'll need to add public getters and setters that can be used to access the properties.

Answer 6

you should change you Object class.. add getter and setter method.. here is example :

public class Book{ 
  String myauthor;
  String mytitle;
public Book (String author, String title){
  myauthor=author;
  mytitle=title;
}
public void setAuthor(String Autor){
myauthor=author;
}
public String getAuthor(){
return myauthor;
}
}

and create setter and getter for 'title' too.. if you want to get the title / author, just simply call

Book.getAuthor();

Answer 7

如果您不想在类中使用getter / setter方法，则可以将访问修饰符定义为受static关键字保护的示例，例如：在com.test包下-有两个类，一个是Book类，另一个是BookInSamePackage在Book类中;如果您将属性标题定义为受保护的静态String标题，则在BookInSamePackage类中;您可以这样访问：'Book.title'。如果要在另一个包的类中使用此title属性，则该类需要扩展Book类并可以这样访问：另一个包的子类中的Book.title。