java “不兼容的类型：字符串不能转换为人”？

"Incompatible types: String cannot be converted to Person"?

提问by Tom K

For class I have to create a Java class definition to describe a car loan taken by two people. It has to contain:

对于类，我必须创建一个 Java 类定义来描述两个人借用的汽车贷款。它必须包含：

1. bankName (a string)
2. accountNumber (an integer)
3. signer (a Person)
4. coSigner (a Person)

1. 银行名称（字符串）
2. accountNumber（整数）
3. 签字人（一个人）
4. 共同签名者（一个人）

It also has to have a getInfo() method which concatenates bankName and accountNumber.

它还必须有一个 getInfo() 方法来连接 bankName 和 accountNumber。

Below is my what I have for the car loan class in which I'm trying to create, but I also have to create another class file called Person.

下面是我尝试创建的汽车贷款类的内容，但我还必须创建另一个名为 Person.class 的类文件。

CarLoan.java:

CarLoan.java：

  package carloandemo.csc212hw01;

  public class CarLoan {

    public static void main(String[] args) {
        String bankName;
        bankName = "Chase";
        int accountNumber;
        accountNumber = 123456;
        Person signer;
        signer = "Rich";
        Person coSigner;
        coSigner = "Tim";
        String print = getInfo(bankName, accountNumber, signer, coSigner);
        System.out.println(print);
        //  System.out.println(getInfo() );
    }

    public static String getInfo(String bankName, int accountNumber, String signer, String coSigner) {
        return "The bank is " + bankName + " and the account number is " + accountNumber + ". " + "The signer of the loan is " + signer + " and the co-signer is " + coSigner + ".";

    }

  }

Person.java:

人.java：

package carloandemo.csc212hw01;

public class Person {

   public String signer;
   public String coSigner;

}

For the code where I assign the Person variables signer and coSigner values, I am recieving an error that says "Incompatible types: String cannot be converted to Person". Because of this I am also receiving that error on the String print statement. How can I fix this? What am I doing wrong?

对于分配 Person 变量 signer 和 coSigner 值的代码，我收到一条错误消息，指出“类型不兼容：字符串无法转换为 Person”。因此，我也在 String 打印语句中收到该错误。我怎样才能解决这个问题？我究竟做错了什么？

回答by Gabriele Mariotti

You can't do it.

你不能这样做。

Person signer;
signer = "Rich";

You are defining signer as a Person, and you are assigning a Stringvalue.

您将签名者定义为 a Person，并且您正在分配一个String值。

First of all You have to init the signerto a new Person(), then you can assign the variable inside the new instance.

首先，您必须将 a 初始化signer为 a new Person()，然后您可以在新实例中分配变量。

For example:

例如：

Person signer = new Person();
signer.signer = "Rich";

May be you can change your code in this way:

也许您可以通过这种方式更改代码：

public class Person {
    public Person(String name, String surname) {
        this.name = name;
        this.surname = surname;
    }

    private String name;
    private String surname;

    //getter
}

public class CarLoan {
    public static void main(String[] args) {
        String bankName;
        bankName = "Chase";
        int accountNumber;
        accountNumber = 123456;

        Person signer = new Person("Rich" , "xxx");
        Person cosigner = new Person("Tim" , "xxx");

        //...
    }
}

回答by Eric J.

This is a case where the error message is telling you exactly what the problem is

在这种情况下，错误消息准确地告诉您问题是什么

“Incompatible types: String cannot be converted to Person”?

“不兼容的类型：字符串不能转换为人”？

Your problem is here

你的问题在这里

Person signer;
signer = "Rich";

"Rich" is a string, not a person.

“富”是一个字符串，而不是一个人。

Create a new instance of Person and then assign "Rich" to the signerproperty of that instance.

创建一个新的 Person 实例，然后将“Rich”分配给signer该实例的属性。

Person person = new Person();
person.signer = "Rich";

Note though looking at this code:

请注意，虽然查看此代码：

Person coSigner;
coSigner = "Tim";
String print = getInfo(bankName, accountNumber, signer, coSigner);

you probably don't actually want the Personobject to contain the signerand coSignerproperties. A better definition is probably

您可能实际上并不希望Person对象包含signer和coSigner属性。更好的定义可能是

public class Person {
    public String name;
    // Other things that describe a person here
}

If you change Person that way, your final code would be

如果您以这种方式更改 Person，您的最终代码将是

Person signer = new Person();
signer.name = "Rich";
Person coSigner = new Person();
coSigner.name = "Tim";
String print = getInfo(bankName, accountNumber, signer, coSigner);