Question

我正在制作一个为我设置实验的程序，我想按字母顺序排列我输入的主题（或人）。我有一个类型主题的arraylist，我想用他们的名字按字母顺序排列。

import java.util.Random;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;

public class Experiment
{
public Random number;
public ArrayList<String> allSubject;
public ArrayList<Subject> allSubjects,alphaSubjects;
public ArrayList<Group> experiment;
public Integer value;
public HashMap<Integer,Subject> matched;
private ArrayList<Integer> numbers;
/**
 * Make a new Experiment.  Then use method addSubject to add
 * Subjects to your experiment.  Then call the assignGroups
 * method to assign Subjects to each group.
 */
public Experiment()
{
    number = new Random();
    numbers = new ArrayList<Integer>();
    experiment = new ArrayList<Group>();
    matched = new HashMap<Integer,Subject>();
    allSubjects = new ArrayList<Subject>(); 
    allSubject = new ArrayList<String>();
    alphaSubjects = new ArrayList<Subject>();
}

/**
 * Alphabetizes the list of Subjects based on their
 * name input by the user.  As of right now, this method
 * is case sensitive meaning Strings starting with 
 * capitals will be listed before those without capitals.
 */
private void alphabetize()
{

           Collections.sort(allSubject);

        //compare the String arraylist to the subject arraylist to reset the subject arraylist indeces in alphabetical order.

       for(int i =0;i<allSubject.size();i++)
       {
        String theName = allSubject.get(i);
         for(Subject subject:allSubjects)
        {
          if(subject.getName().toLowerCase().contains(theName))
         {
            alphaSubjects.add(new Subject(subject.getName(),subject.getDescription()));
         }
        }

     }
}
/**
 * Adds a new Subject to the experiment.
 */
public void addSubject(String name, String description)
{
    allSubjects.add(new Subject(name,description));
    allSubject.add((name.toLowerCase()));
}

因此，不必将主题添加到arraylist，然后必须从该主题中删除名称并将其添加到完全不同的arraylist，是否有办法按主题的名称按字母顺序排列。

哦，这里是班级：主题。

public class Subject
{
public final String name;
public final String description;
public Subject(String name, String description)
{
    this.name = name;
    this.description = description;
}
public Subject(int aNumber)
{
    name = "Subject" + aNumber;
    aNumber++;
    description = "default";
}
public String getName()
{
    return name;
}
public String getDescription()
{
    return description;
}

}

Answer 1

您可以使用自己的比较器将主题ArrayList与SortedList（http://www.glazedlists.com/documentation/tutorial-100#TOC-Sorting-Tables-Sorting-Tables）包装在一起。

SortedList sortedSubjects = new SortedList<Subject>(allSubjects,new Comparator<Subject>() {
        @Override
        public int compare(Subject left, Subject right) {
            return left.getName().compareTo(right.getName);
        }
    });

Answer 2

您可以实现Comparator或Comparable并根据您的说服覆盖compare（..），compareTo（..）方法。在您的情况下，您需要在实现此方法时考虑“主题的名称”。然后Collections.sort(yourList<Subject>)将根据主题名称为您提供排序结果。

    import java.util.ArrayList;
import java.util.Collections;
import java.util.List;


public class Subject implements Comparable<Subject>
{
public final String name;
public final String description;
public Subject(String name, String description)
{
    this.name = name;
    this.description = description;
}
public Subject(int aNumber)
{
    name = "Subject" + aNumber;
    aNumber++;
    description = "default";
}
public String getName()
{
    return name;
}
public String getDescription()
{
    return description;
}

    @Override
    public int compareTo(Subject o) {
        return this.getName().toUpperCase().compareTo(((Subject)o).getName());
    }

    public static void main(String[] args) {
        Subject s3 = new Subject("C","");
        Subject s1 = new Subject("Z","");
        Subject s2 = new Subject("A","");

        List<Subject> list = new ArrayList<Subject>();
        list.add(s1);
        list.add(s2);
        list.add(s3);

        Collections.sort(list);

        for(Subject sub:list){
            System.out.println(sub.getName());
        }
    }
}

Answer 3

您需要做的就是让您的班级工具Comparable并添加compareTo()：

public class Subject implements Comparable<Subject>
{
    ....

     @Override
     public int compareTo(Subject other)
     {
         return this.getName().compareTo(other.getName());
     }
}

现在，由于您的类实现了自己的Comparable，因此您可以使用Collections.sort()对Subjects列表进行排序。

这是一个tutorial以获取更多信息。祝你好运！

我想通过其类中定义的变量按字母顺序对象

3 个答案: