如何在Java中创建一个Array，ArrayList，Stack和Queue？ [英] How to create an Array, ArrayList, Stack and Queue in Java?

问题描述

我正在阅读Java文章，但在声明中没有发现任何差异，并且被混淆了。任何人都可以列出我吗？

添加文章

http://www.theparticle.com/javadata2.html

解决方案

没有关于什么问题正在提出的更多细节，我将回答问题的标题，

创建一个 Array ：

  String [] myArray = new String [2]; 
 int [] intArray = new int [2]; 
 
 //或可以声明如下
 String [] myArray = {this，is，my，array}; 
 int [] intArray = {1,2,3,4}; 
  

创建一个 ArrayList ：

  ArrayList< String> myList = new ArrayList< String>（）; 
 myList.add（Hello）; 
 myList.add（World）; 
 
 ArrayList< Integer> myNum = new ArrayList< Integer>（）; 
 myNum.add（1）; 
 myNum.add（2）; 
  

这意味着，创建一个 ArrayList code> String 和整数对象。你 不能 使用 int ，因为这是一个原始数据类型，请参阅原始数据类型列表的链接。

创建 堆栈 ：

 堆栈myStack = new Stack（）; 
 //添加任何类型的元素（String，int等）
 myStack.push（Hello）; 
 myStack.push（1）; 
  

创建一个 队列 :(使用LinkedList ）

 队列< String> myQueue = new LinkedList< String>（）; 
队列<整数> myNumbers = new LinkedList< Integer>（）; 
 myQueue.add（Hello）; 
 myQueue.add（World）; 
 myNumbers.add（1）; 
 myNumbers.add（2）; 
  

与 ArrayList 相同的东西，这个声明意味着创建一个 cue String 和 Integer / p>

---

更新：

为了回应您对其他人的评论给出答案，

我现在很困惑，为什么要使用字符串。而< String> 意味着

我们使用 String 只是一个纯粹的例子，但你可以添加任何其他对象，但主要的是你使用一个对象 strong> 不是 一个原始类型。每个基本数据类型都有自己的原始包装类，请参阅原始数据类型的包装类列表的链接

我已经发布了一些链接来解释两者之间的区别，但是这里是一个原始类型的列表

• byte


• short li>
  
• char


• int li>
  
• long


• boolean li>
  
• double


• float li>
  

这意味着你不能像这样做一个整数的 ArrayList

  ArrayList< int> number = new ArrayList< int>（）; 
 ^应该是一个对象，int不是一个对象，而是整数就是！ 
 ArrayList< Integer> numbers = new ArrayList< Integer>（）; 
 ^完全有效
  

此外，您可以使用自己的对象，这里是我的我创建的怪物对象

  public class Monster {
 String name = null; 
 String location = null; 
 int age = 0; 
 
 public Monster（String name，String loc，int age）{
 this.name = name; 
 this.loc = location; 
 this.age = age; 
} 
 
 public void printDetails（）{
 System.out.println（name +来自+ location + 
，为+ age +旧。）; 
} 
} 
  

这里我们有一个怪物对象，但现在在我们的 Main.java 类中，我们要保留我们所有的 Monster 我们创建，所以我们将它们添加到一个 ArrayList

  public class Main {
 ArrayList< Monster> myMonsters = new ArrayList< Monster>（）; 
 
 public Main（）{
 Monster yetti = new Monster（Yetti，The Mountains，77）; 
怪物lochness =新怪物（Lochness怪物，苏格兰，20）; 
 
 myMonsters.add（yetti）; //<  - 将Yetti添加到我们的列表
 myMonsters.add（lochness）; //<  - 添加Lochness到我们的列表
 
 for（Monster m：myMonsters）{
 m.printDetails（）; 
} 
} 
 
 public static void main（String [] args）{
 new Main（）; 
} 
} 
  

（我帮助了我女朋友的兄弟Java游戏，他也必须做这些事情，但我希望这个例子被很好地证明了）

I was reading a Java article, but found no differences in the declaration and was confused over. Can anyone list me out this?

Added the Article

http://www.theparticle.com/javadata2.html

解决方案

Without more details as to what the question is exactly asking, I am going to answer the title of the question,

Create an Array:

String[] myArray = new String[2];
int[] intArray = new int[2];

// or can be declared as follows
String[] myArray = {"this", "is", "my", "array"};
int[] intArray = {1,2,3,4};

Create an ArrayList:

ArrayList<String> myList = new ArrayList<String>();
myList.add("Hello");
myList.add("World");

ArrayList<Integer> myNum = new ArrayList<Integer>();
myNum.add(1);
myNum.add(2);

This means, create an ArrayList of String and Integer objects. You cannot use int because thats a primitive data types, see the link for a list of primitive data types.

Create a Stack:

Stack myStack = new Stack();
// add any type of elements (String, int, etc..)
myStack.push("Hello");
myStack.push(1);

Create an Queue: (using LinkedList)

Queue<String> myQueue = new LinkedList<String>();
Queue<Integer> myNumbers = new LinkedList<Integer>();
myQueue.add("Hello");
myQueue.add("World");
myNumbers.add(1);
myNumbers.add(2);

Same thing as an ArrayList, this declaration means create an Queue of String and Integer objects.

---

Update:

In response to your comment from the other given answer,

i am pretty confused now, why are using string. and what does <String> means

We are using String only as a pure example, but you can add any other object, but the main point is that you use an object not a primitive type. Each primitive data type has their own primitive wrapper class, see link for list of primitive data type's wrapper class.

I have posted some links to explain the difference between the two, but here are a list of primitive types

• byte
• short
• char
• int
• long
• boolean
• double
• float

Which means, you are not allowed to make an ArrayList of integer's like so:

ArrayList<int> numbers = new ArrayList<int>(); 
           ^ should be an object, int is not an object, but Integer is!
ArrayList<Integer> numbers = new ArrayList<Integer>();
            ^ perfectly valid

Also, you can use your own objects, here is my Monster object I created,

public class Monster {
   String name = null;
   String location = null;
   int age = 0;

public Monster(String name, String loc, int age) { 
   this.name = name;
   this.loc = location;
   this.age = age;
 }

public void printDetails() {
   System.out.println(name + " is from " + location +
                                     " and is " + age + " old.");
 }
} 

Here we have a Monster object, but now in our Main.java class we want to keep a record of all our Monster's that we create, so let's add them to an ArrayList

public class Main {
    ArrayList<Monster> myMonsters = new ArrayList<Monster>();

public Main() {
    Monster yetti = new Monster("Yetti", "The Mountains", 77);
    Monster lochness = new Monster("Lochness Monster", "Scotland", 20);

    myMonsters.add(yetti); // <-- added Yetti to our list
    myMonsters.add(lochness); // <--added Lochness to our list

    for (Monster m : myMonsters) {
        m.printDetails();
     }
   }

public static void main(String[] args) {
    new Main();
 }
}

(I helped my girlfriend's brother with a Java game, and he had to do something along those lines as well, but I hope the example was well demonstrated)

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