java - 如何使用 ArrayList 在寄存器中查找名称

Question

我目前正在研究以下问题:

Assume a class Name has attributes "surname" and "firstname" stored as Strings. Let "regist" be a list of Name with declaration:

ArrayList<Name> regist = new ArrayList<Name>();

Assuming that "regist" is populated, implement the method below that finds a name in the list with the given surname, or returns null if no matching name exists in the list. (You may write Java code or a mix of Java and pseudo-code).

public Name find(String surname)
{
  //... to do ...
}

到目前为止我能够得到的答案是:

public Name find (String surname)
{
  this.surname = surname;
  return null;
}


public Name()
{
  surname = " ";
}

之后，我就被困在这里了，如果有人能告诉我如何完成这段代码，那么我将非常感谢您的帮助，提前致谢。

(如果我能够正确完成此代码，我将能够正确测试该代码)。

Answer 1

您必须循环遍历 regList 中的项目并返回具有给定姓氏的 Name 对象。您当前的 find 代码不正确 - find 方法不在 name 类中，并且(或不应)被允许直接更改 Name 对象内的变量。

无论如何，解决方案是:

public Name find(String surname)
{
    for(Name obj : regList)
    {
       // Check the object's surname with the given one
       // Should check if obj is null
       // Must use .equals to compare strings.
       if(obj.surname.equals(surname))
           return obj;
    }

    // Not found
    return null;
}