将字符串添加到 ArrayList [英] Adding Strings to an ArrayList

问题描述

我需要确保我正确地构建了这个程序.我必须编写一个使用 ArrayList 容器并在其中放入 5 个字符串的程序，然后从 ArrayList 中打印出 5 个字符串.我是 ArrayList 的新手，所以想确保我满足了要求.

I need to make sure I am building this program right. I have to write a program that uses an ArrayList container and put 5 Strings in it and then print out the 5 Strings from the ArrayList. I am new to ArrayList's so want to make sure I have the requirements fulfilled.

我的问题是:这是创建字符串、创建 ArrayList、将字符串添加到列表然后打印列表的正确方法吗?"

My question is: "Is this the proper way to Create Strings, Create an ArrayList, add the Strings to the List and then Print the List?"

public static void main(String[] args) 
{

ArrayList<String> names_and_numbers = new ArrayList<>();
String bob = "bob";
String nancy = "nancy";
String jim = "jim";
String claire = "claire";

names_and_numbers.add( bob ); 
names_and_numbers.add( nancy ); 
names_and_numbers.add( jim );
names_and_numbers.add( claire );      

for (String e : names_and_numbers)  
{  
 System.out.println(e);  
} 

int six = 6;
String numbers = "";

ArrayList<Integer> myList = new ArrayList<>();

myList.add( 1 ); 
myList.add( 2 ); 
myList.add( 3 );
myList.add( 4 );
myList.add( 5 );
myList.add(six);        

for (int x : myList)  
{  
 System.out.println(x);  
}     

//System.out.println(myList);   
//System.out.println(names_and_numbers);   
}
}

推荐答案

你做得很好，我没有看到问题，但我认为 arraylists 存储对象，所以如果你想要一个整数，请构建一个对象.我想如果你能编译它，这会自动完成.

You're doing ok, I don't see a question but I think that arraylists store objects, so if you want an integer, get build an object. I guess if you can compli that, this is done automatically.

Integer i = new Integer(1);
myList.add(i);

或在 1 行中

myList.add(new Integer(1));

正如 Paul Bellora 所说，new Integer(i) 是不必要的，你可以只用 i 替换它.我只是想指出 ArrayLists store objects(不知何故我忘了提到这一点)，而不是像 int 这样的原始数据类型，当你尝试这样做时，数据是如果可能的话(对编译器)转换为 Object 的子对象，就像 Integer 一样.

As Paul Bellora says, new Integer(i) is unnecessary and you can replace it with just i. I just wanted to point out that ArrayLists store objects (somehow i forgot to mention that), not primitive data types like int and when you try to do it, the data is converted if possible (to the compiler) to a child of Object just like Integer.

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