The difference between arrays as Lists in Java?

arrays and lists are part of the data structure, which is essential for software development. They are commonly used data structures. This article will explore the differences between them, the evolution of the array to the list, and its practical cases.

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What is the array

Array is a data structure in computer programming, which is used to store a series of the same data items in continuous memory location. The array is fixed in size and the same data type is stored. They use indexes to provide fast access to elements. For example:

The evolution of the array to the list

int[] arr = {1, 2, 3, 4, 5};  
System.out.println(arr[0]);  // 输出：1

Array is used for data operation, but because they are immutable, they are limited in terms of size and type. The introduction of advanced data structure has led to the development of the list, and the list is more flexible and dynamic. The list can accommodate elements of different data types and can dynamically adjust the size.

In Java, the list is a more common alternative to the traditional array. Examples as follows:

What is the list?

import java.util.ArrayList;

public class Main {
    public static void main(String[] args) {
        ArrayList<Object> myList = new ArrayList<>();
        myList.add(1);          // 添加整数
        myList.add("two");      // 添加字符串
        myList.add(3.0);        // 添加双精度浮点数

        System.out.println(myList);  // 输出：[1, two, 3.0]
    }
}

Java's ArrayList is a structure that can adjust the size of similar arrays. If it is declared by Object's generic types, it can accommodate different types of objects.

List is an abstract data type, which is used as a sorting collection of projects. I found that the list can accept different data types, dynamic changes in size, and support various operations, such as adding or deleting elements (as shown in the above example). The list is widely used for various applications, from data organization to algorithm implementation. Examples in real life may be the list of names of

Manageing the classroom students

.

Example:

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The array is used as a list

import java.util.ArrayList; 

public class Classroom { 
    public static void main(String[] args) { 
        ArrayList<String> students = new ArrayList<>(); 

        // 添加学生姓名
        students.add("Alice"); 
        students.add("Bob"); 
        students.add("Charlie"); 

        // 访问学生姓名
        System.out.println("第一位学生： " + students.get(0)); // 输出：Alice 

        // 删除学生
        students.remove("Bob"); 

        // 遍历列表
        System.out.println("教室里的学生："); 
        for (String student : students) { 
            System.out.println(student); 
        } 
    } 
} 

Although the array is used in the same type of elements, they can simulate the list behavior under certain circumstances. For example, in certain languages, the list operation can be used to adjust the size of the array. This is an example

The situation of the array as a list

The use of arrays as a list is very suitable for cases that require fixed size collection and type consistency very important. However, for applications that need to be inserted or deleted frequently, they may not be ideal, because modifying the array may need to re -assign memory, resulting in low efficiency.

import java.util.ArrayList;

public class Main {
    public static void main(String[] args) {
        ArrayList<Integer> arr = new ArrayList<>(); // 创建一个 Integer 类型的 ArrayList
        arr.add(1);  // 添加元素 1
        arr.add(2);  // 添加元素 2
        arr.add(3);  // 添加元素 3
        arr.add(4);  // 添加元素 4

        System.out.println(arr);  // 输出：[1, 2, 3, 4]

        arr.remove(1); // 删除索引 1 处的元素（值 2）
        System.out.println("删除元素后的 ArrayList： " + arr);


    }
}

What will happen if the array is used to need ArrayList?

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The advantages of the array as a list

Due to continuous memory distribution, the array provides higher speeds, which can be quickly visited. When operating large unified data type datasets, they can also minimize overhead.

Frequent errors with ArrayList

The common errors that are used as a list of arrays include assumptions that array can dynamically adjust the size without having consequences, ignoring the confusion between the type consistency and the zero -based index and a base index. Click here to read more content to avoid certain types of errors.

In short, programmers should understand the difference between the array and ArrayList in order to better programming. Understanding when they use them to avoid errors.

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