Java 类型字符串的方法未定义
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the method is undefined for the type string
提问by user1347096
why would I have "the method is undefined for the type string" in java with this statement:
为什么我会在 java 中使用以下语句“未定义类型字符串的方法”：
if(book.getTitle().getAuthor().getAward()){..}
the error is for getAward()
错误是针对 getAward()
when I have defined a class Author as this:
当我定义一个类 Author 时：
class Author {
private String name;
private boolean award;
public Author(String n, boolean p){
name=n;
award=p;
}
public String getName(){return name;}
public boolean getAward(){return award;}
} May the error come from another definition (other than Author?)
错误可能来自另一个定义（除了作者？）
采纳答案by Stephen C
actually get Author is in another class and returns a string. getTitle is from a third class and returns string as well. Book is from a fourth class.
实际上 get Author 在另一个类中并返回一个字符串。getTitle 来自第三个类，也返回字符串。书是第四班的。
Then the answer is obvious.
那么答案就显而易见了。
You are attempting to call getAuthor()on the result of calling getTitle(). But the result of getTitle()is a String... and Stringdoesn't have a getAuthor()method.
您正在尝试调用调用getAuthor()的结果getTitle()。但结果getTitle()是String... 并且String没有getAuthor()方法。
And that is exactly what the compilation error is telling you.
这正是编译错误告诉你的。
In fact, you probably should write:
事实上，你可能应该写：
if(book.getAuthor().getAward()){..}
then change getAuthor()to return the Auteurobject ... rather than the author's name.
然后更改getAuthor()以返回Auteur对象...而不是作者的姓名。
A book (Oevre) has an author, but a title (String) does not.
一本书 (Oevre) 有作者，但书名 (String) 没有。
回答by RMachnik
change your getAuthor()method implementation to that
将您的getAuthor()方法实现更改为
public Author getAuthor(){
return new Author(); // or some author that is set in your object
}
And on that you can performe another method.
if(book.getTitle().getAuthor().getAward())if Author class have method getAward
并且您可以执行另一种方法。
if(book.getTitle().getAuthor().getAward())如果 Author 类有方法getAward
public class Author{
public boolean getAward(){ // implementation
}
}
回答by Sajan Chandran
You need to change your getAuthormethod to
你需要改变你的getAuthor方法
public Author getAuthor(){
return author;
}
and if you want the authorsaward, then u should invoke
如果你想要authorsaward，那么你应该调用
book.getAuthor().getAward()
book.getAuthor().getAward()
