我正在使用数组为Java编写地址簿作业。我不知道如何在添加它们之前确保某人不在地址簿中，并确保它们在地址簿中以便删除它们。我有三个文件;希望我能正确地将代码复制到这里。关于我做错的任何想法都是最受欢迎的。
这是AddressBook类：
package addressbook;
public class AddressBook
{
// declaring variable addressBook as reference
// to an array of Person objects
Person[] addressBook;
// using a static field to keep track of
// the number of person objects
public static int people = 0;
// allocate memory for the array field in a constructor
public AddressBook()
{
addressBook = new Person[2];
}
//Method to add a person object to the addressBook
public void AddPerson(Person person)
{
for (int i = 0; i < people; i++)
{
if (addressBook[i] != person)
{
// check to see if the number of person objects
// is fewer than the number of spaces in the array
if (people < addressBook.length)
{
// add new person to array at the position
// specified by variable people (starting with 0)
addressBook[people] = person;
} // if there are too many person objects
// to fit in the address book
else
{
// declare a temp array twice the length of address book
Person[] temp = new Person[addressBook.length * 2];
for (int j = 0; j < addressBook.length; j++) // put the references from the old address book into temp
{
temp[j] = addressBook[j];
}
//add the new person object into temp
temp[people] = person;
// copy the reference to temp into address book
addressBook = temp;
}
// increase person object count (since you just added a person)
people++;
// print to the console to see if method is working
System.out.println("people = " + people + "\n"
+ "addressBook.Length = " + addressBook.length);
}
}
}
// Method to search for a person by name.
// Searches both first and last names
// and puts the results into an array.
public Person[] searchName(String name)
{
Person[] searchResults = new Person[addressBook.length];
for (int i = 0; i < people; i++)
{
if ((addressBook[i].firstName.equals(name))
|| (addressBook[i].lastName.equals(name)))
{
searchResults[i] = addressBook[i];
}
}
return searchResults;
}
// Method to search for a person by ID number.
// Puts the results into an array.
public Person[] searchID(int id)
{
Person[] resultsList = new Person[addressBook.length];
for (int i = 0; i < people; i++)
{
if (addressBook[i].idNumber == id)
{
resultsList[i] = addressBook[i];
}
}
return resultsList;
}
//Method to remove a person object from the addressBook
public void removePerson(int id)
{
for (int i = 0; i < people; i++) // Search by ID number.
{
if (addressBook[i].idNumber == id)
{
// copy the ref to the last person object in array
// into the index location of the person object being removed
addressBook[i] = addressBook[people - 1];
// set the ref of the (formerly) last person object to null
addressBook[people - 1] = null;
// decrease person object count (since you just removed a person)
people--;
}
}
// If your count of people is 25% or less than the
// length of your address book
if (people <= (addressBook.length / 4))
{
// declare a temp array half the length of address book
Person[] temp = new Person[addressBook.length / 2];
for (int j = 0; j < people; j++) // put the references from the old address book into temp
{
temp[j] = addressBook[j];
}
// copy the reference to temp into address book
addressBook = temp;
}
// print to the console to see if method is working
System.out.println("Count= " + people + "\n"
+ "addressBook.Length= " + addressBook.length);
}
// Prints the array to the console
public void PrintAddressBook()
{
for (int i = 0; i < addressBook.length; i++)
{
System.out.println(addressBook[i]);
}
}
}
这是Person类：
package addressbook;
public class Person
{
public String firstName, lastName;
public int idNumber = 0;
public static int nextIdNumber;
public Person(String fn, String ln)
{
firstName = fn;
lastName = ln;
nextIdNumber++;
idNumber = nextIdNumber;
}
public String getFirstName()
{
return firstName;
}
public void setFirstName(String newFirstName)
{
firstName = newFirstName;
}
public String getLastName()
{
return lastName;
}
public void setLastName(String newLastName)
{
lastName = newLastName;
}
@Override
public String toString()
{
return ("First name: " + firstName + "\n"
+ "Last name: " + lastName + "\n"
+ "Full name: " + firstName + " " + lastName + "\n"
+ "ID number: " + idNumber);
}
public void printInformation()
{
System.out.println(lastName + ", " + firstName + ", " + idNumber);
}
}
这是AddressBookTester：
package addressbook;
public class AddressBookTester {
public static void main(String[] args) {
AddressBook addressBook = new AddressBook();
System.out.println("-----Testing a Person Constructor-----");
System.out.println("--------using ToString Method--------\n");
Person person1 = new Person("Helen", "Mirren");
System.out.println(person1);
System.out.println();
Person person2 = new Person("Helen", "Thomas");
System.out.println(person2);
Person person3 = new Person("Thomas", "Wolfe");
System.out.println(person3);
Person person4 = new Person("Robert", "Redford");
System.out.println(person4);
Person person5 = new Person("Robbie", "Robertson");
System.out.println(person5);
System.out.println("--Testing Add Person Method--");
addressBook.AddPerson(person1);
addressBook.AddPerson(person2);
addressBook.AddPerson(person3);
addressBook.AddPerson(person4);
addressBook.AddPerson(person5);
addressBook.PrintAddressBook();
System.out.println("----Testing Search by Name Method------");
//create return Person object array for searchName function
Person[] searchList = addressBook.searchName("Helen");
for (int i = 0; i < searchList.length; i++) {
System.out.println(searchList[i]);
}
System.out.println("----Testing Search by ID Method------");
Person[] results = addressBook.searchID(5);
for (int i = 0; i < results.length; i++) {
System.out.println(results[i]);
}
System.out.println("----Testing Remove Person Method------");
addressBook.removePerson(4);
addressBook.removePerson(3);
addressBook.removePerson(2);
addressBook.PrintAddressBook();
}
}
当我运行它时，我得到：
/*run:
-----Testing a Person Constructor-----
--------using ToString Method--------
First name: Helen
Last name: Mirren
Full name: Helen Mirren
ID number: 1
First name: Helen
Last name: Thomas
Full name: Helen Thomas
ID number: 2
First name: Thomas
Last name: Wolfe
Full name: Thomas Wolfe
ID number: 3
First name: Robert
Last name: Redford
Full name: Robert Redford
ID number: 4
First name: Robbie
Last name: Robertson
Full name: Robbie Robertson
ID number: 5
--Testing Add Person Method--
null
null
----Testing Search by Name Method------
null
null
----Testing Search by ID Method------
null
null
----Testing Remove Person Method------
Count= 0
addressBook.Length= 1
Count= 0
addressBook.Length= 0
Count= 0
addressBook.Length= 0
BUILD SUCCESSFUL (total time: 0 seconds)
*/
感谢有关如何修复此代码的任何想法。我很擅长编码，显然......
答案 0 :(得分：0)
我现在无法彻底阅读您的代码，但我会尝试对我观察到的一些问题提供一些提示。
没有。 1：
在searchX()方法中，您返回的数组Person与地址簿的大小完全相同。在循环地址簿的方法中（提示使用foreach而不是索引循环），然后调用searchResults[i] = addressBook[i];。这可能会导致结果数组中的大量空条目。
您可能希望为searchResults添加不同的索引，并仅在添加条目时增加该索引。这样所有的空条目都在数组的末尾，您可以轻松地复制该数组，并在最后省略空白部分。
没有。 2：
一般情况下，如果您允许使用List，Set等集合，请使用这些集合而不是数组。
没有。 3：
不要将对象与{= 1}中的==或！=进行比较，因为您可以使用相同的数据创建两个对象，并且您不会看到它们因为==比较对象的缩进而不是相等。
没有。 4：
在致电if( addressBook[i] != person)时，您未获得打印状态，这表明存在错误。
尝试并调试您的代码，您应该看到addPerson()将导致无迭代，因为for (int i = 0; i < people; i++)最初为0，因此永远不会满足people。因此，没有任何东西被添加到你的数组中。
我认为这是真正的问题：
您的i < 0方法结构错误。除了上面提到的addPerson问题之外，您还要多次添加每个新人，因为您不会终止循环，但只要i < 0每个条目都适用，就会添加该人。在新人的情况下阵列。
尝试将其更改为以下伪代码：
addressBook[i] != person没有。 5：
作为旁注，请尝试坚持Java代码约定，例如方法名称始终以小写字母开头，即boolean personInArray = searchById( person.getId() );
if( !personInArray ) {
if( people == addressBook.length) {
//resize the array, since it is full and the person should be added
}
//add the person
addressBook[people] = person;
people++;
}
而不是addPerson。虽然这更像是一种风格问题，但它可以帮助您和其他人调试和理解您的代码。
答案 1 :(得分：0)
首先是一个非常明确的问题：
首先将person计数管理员初始化为0，然后在AddPerson()方法中启动循环执行：
for(int i=0;i<person;i++){
...
}
从person = 0起，它甚至不会进入循环，因为0不小于0.
其次，您正在对对象执行==比较，这肯定会出错。原因如下：
==和!=是参考比较，即==仅在被比较的两个对象引用内存中的同一对象时才返回true。
相反，您应该使用.equals(...)函数，但由于您的Person类没有扩展任何内容，因此默认使用Object.equals()超类方法，这与上面的方法相同。
因此，进行比较的正确方法是覆盖equals()类的Person方法，使其返回true，例如名字和姓氏相同，或者以您的标准为准。同时，您还应确保覆盖hashCode()方法以遵守这两种方法之间的约定。您可以阅读更多相关信息，例如这里：
http://javarevisited.blogspot.dk/2011/02/how-to-write-equals-method-in-java.html