Usage of arrayList in java

ArrayList in Java is a dynamic array that allows elements to be quickly added, removed, and accessed, and can automatically resize to accommodate new elements. Its usage includes: creating ArrayList, adding elements, deleting elements, getting elements and traversing ArrayList. Features are: dynamic size, fast access, orderly, repeatable. The advantages are efficient addition and deletion operations, fast access to elements, and the ability to store any type of object. The limitation is that the performance of inserting or deleting elements at random locations is poor, and accessing out-of-range elements will throw an exception.

Usage of ArrayList in Java

ArrayList is a dynamic array in the Java collection framework, used for storage Collection of objects. It allows elements to be quickly added, removed and accessed, and can automatically resize to accommodate new elements.

Usage:

1. Create ArrayList:

   <code class="java">ArrayList<Integer> numbers = new ArrayList<>();</code>

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2. Add element:

   <code class="java">numbers.add(10);
   numbers.add(20);</code>

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3. Delete element:

   <code class="java">numbers.remove(0); // 删除第一个元素</code>

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4. Get element:

   <code class="java">int firstNumber = numbers.get(0);</code>

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5. Traverse ArrayList:

   <code class="java">for (int number : numbers) {
    System.out.println(number);
   }</code>

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Features:

• Dynamic Size: ArrayList can be automatically resized as needed without explicit adjustment.
• Fast access: ArrayList provides fast index-based element access with a time complexity of O(1).
• Ordered: The elements in the ArrayList are stored in insertion order.
• Repeatable: ArrayList allows storing repeated elements.

Advantages:

• Add and delete operations are efficient.
• Access elements quickly.
• Can store any type of object.

Limitations:

• Performance of inserting or deleting elements at random locations is poor.
• Accessing an element out of range will throw an exception.

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