collections

问题 I've got a simple java pojo which looks like this: class MyClass { public String getGroup(); public String getTitle(); } Now what I want to do is to primarily sort a list of MyClass pojo by the values returned by the getTitle() method. Easy going though using my own comparator. However, what I want is that instances with the same value returned by getGroup() being followed by each other. Now what I did was something like .. compare(MyClass c1, MyClass c2) { if (c1.getGroup().compareTo(c2

问题 I have Student table, Course table and a StudentCourse table. On my WPF, I'm making "Student" selections with combo box. How can I display the corresponding Course and its properties(CourseID, CourseName, Credit) in a listview, using ObservableCollection?. Here's my code for the combo box SelectionChanged event private void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e) { int MySelect = (int)this.comboBox1.SelectedValue; var SelectedStudent = db.Students.Include(

问题 I'm filling up the JVM Heap Space. Changing parameters to give more heap space to the JVM, or changing something in my algorithm in the code not to use so much space are two of the most recommended options. But, if those two have already been tried and applied, and I still get out of memory exceptions, I'd like to see what the other options are. I found out about this example of "Using a memory mapped file for a huge matrix" and a library called HugeCollections which are an interesting way to

问题 I'm trying to get familiar with Collections. I have a String which is my key, email address, and a Person object (firstName, lastName, telephone, email). I read in the Java collections chapter on Sun's webpages that if you had a HashMap and wanted it sorted, you could use a TreeMap. How does this sort work? Is it based on the compareTo() method you have in your Person class? I overrode the compareTo() method in my Person class to sort by lastName. But it isn't working properly and was

问题 I have a simple class called Team, that looks like this: public class Team { public Team ParentTeam; public string Name; } So it has a Name and a reference to another team that is its Parent Team. I now have a list of Teams that I am getting back from a function List<Team> list = GetTeamsList(); Given, a few assumptions: All teams have a ParentTeam except one (the top team) Every team returned in the list is part of the same hierarchy and its only a single hierarchy (no 2 teams at the same

问题 I want to render a filtered collection as a checkbox list. But i have trouble to get the collection shown. i get "Catchable Fatal Error: Object of class Doctrine\ORM\PersistentCollection could not be converted to string". Below is my formtype: class PropertyfilterType extends AbstractType { public function buildForm(FormBuilderInterface $builder, array $options) { $builder ->add('view', EntityType::class, [ 'class' => Propsearch::class, 'choice_label' => 'propsearchviews', 'expanded' => true,

问题 I have List<SomeData> data; public class SomeData { public int Key { get; set;} public decimal Value { get; set;} } Also i have List<int> DataOrder; I need to sort List<SomeData>data by Key , placing it in same order as List<int> DataOrder values. Is there any common algorithms for that? Example: List<SomeData> data = new List<SomeData>(); data.Add(new SomeData{ Key = 10, Value = 14 }) data.Add(new SomeData{ Key = 25, Value = 22 }) data.Add(new SomeData{ Key = 567, Value = 3 }) data.Add(new

问题 This question already has answers here : What is the best way to modify a list in a 'foreach' loop? (11 answers) Closed 6 years ago . There is a typical collection of some class objects e.g. string for a simplicity IList<string> collection = new List<string>(); During the program flow some function needs to operate on the collection, process class object and depending on the result of operation remove processed class object from collection. E.g. following example of strings if string is

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . I have the following class: class A { ArrayList<String> s = new ArrayList<>(); double d = Double.MAX_VALUE; } I've an arrayList of

问题 The Java class CircularFifoBuffer in the package org.apache.commons.collections.buffer is non-generic, and can store objects of any class. I would like to create a generified version of this, that can only hold objects of class T. My first thought was to extend CircularFifoBuffer and simply write a new 'add' method: public class CircularFifoQueue<T> extends CircularFifoBuffer { public boolean add(T data) { return super.add(data); } } However, this leaves the old 'add' method in place,