Java排序對象的陣列列表

Question

我試圖按照Sort an arraylist of objects in java的建議在我的程序中實現排序方法，但無法實現此功能。我得到的錯誤 「無法找到符號 - 方法排序（）」

Appologies即時通訊新到Java ..

入門級：

/** 
* The Entry class represents a persons address entry into the system. 
* It holds the persons name and address information 
* 
*/ 
public class Entry 
{ 
// the person's full name 
private String name; 
// the steet namd or number 
private String street; 
// the town 
private String town; 
// postcode 
private String postcode; 

/** 
* Create a new entry with a given name and address details. 
*/ 
public Entry(String strName, String strStreet, String strTown, String strPostcode) 
{ 
    name = strName; 
    street = strStreet; 
    town = strTown; 
    postcode = strPostcode; 
} 

/** 
* Return the address for this person. The address shows the 
* street, town and postcode for the person 
* @return address 
*/ 
public String getAddress() 
{ 
    return name + ", " + street + ", " + town + ", " + postcode; 
} 

} 

AddressBook類：

import java.util.*; 

/** 
* The AddressBook class represents an address book holding multiple persons details. It stores 
* the name, street, town, postcode and number of entries. 
*/ 
public class AddressBook 
{ 
private ArrayList <Entry> entries; 

/** 
* Create a an AddressBook with no limit on the number of entries 
*/ 
public AddressBook() 
{ 
    entries = new ArrayList <Entry>(); 
} 

/** 
* Return the number of address book entries 
* @return the entry amount 
*/ 
public String getAddressBook() 
{ 
    String listEntries = "Address Book\n"; 

    listEntries = listEntries + "\nNumber of entries: " + numberOfEntries() +"\n"; 

    entries.sort(); 

    for (int i = 0; i < entries.size(); i++) { 
      System.out.println(entries.get(i)); 
      } 
    return listEntries; 
} 

AddressBookTextUI類別：

import java.util.*; 
import java.util.regex.Matcher; 
import java.util.regex.Pattern; 


/** 
* Provides a text based user interface for the AddressBook project. 
* 
*/ 
public class AddressBookTextUI { 
private AddressBook addressBook; 
Scanner myScanner; 

/** 
* Constructor for objects of class TextUI 
*/ 
public AddressBookTextUI() 
{ 
    addressBook = new AddressBook(); 
    myScanner = new Scanner(System.in); 

} 



private void fullCommand() 
{ 
    System.out.println(addressBook.getAddressBook()); 
    clearScreen(); 
} 

} 

Answer 1

您需要使用Collections.sort(List<T> list)。

列表是一個接口。 ArrayList間接實現List接口。

Answer 2

假設您指的是：entries.sort();，您需要致電Collections.sort(List<T> list)或Collection.sort(List<T> list, Comparator<T> comparator)。

兩者之間的區別在於第一個使用默認行爲，可以通過實現Comparable接口指定的compareTo方法在要分類的對象中指定默認行爲，而第二個允許您傳遞比較對象。這將允許您以不同的方式對相同的列表進行排序。

Answer 3

1. 使詞條實現可比：

   公共類條目實現可比

2. 加INT的compareTo（進入otherEntry）法（簡化僞代碼）：

   if this > otherEntry return 1 
   else if this < otherEntry return -1 
   else return 0 
   

3. 呼叫集合。排序（您的條目數組）