How to use collection framework functions to add, delete, modify and query collections in Java

How to use collection framework functions to add, delete, modify and query collections in Java

Introduction:
In Java programming, collections are a common and important data structure. . When processing data, you can use collections to easily perform operations such as additions, deletions, modifications, and searches. Java provides a wealth of collection framework functions. This article will introduce how to use these functions to perform addition, deletion, modification, and query operations on collections, and provide specific code examples.

1. Creation and initialization of collections
In Java, collections can be created and initialized using classes such as ArrayList, LinkedList, and HashSet. The following are several common ways:

1. Use ArrayList to create a collection and initialize the data:

   import java.util.ArrayList; ArrayList list = new ArrayList(); list.add("apple"); list.add("banana"); list.add("orange");

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2. Use LinkedList to create a collection and initialize the data :

   import java.util.LinkedList; LinkedList list = new LinkedList(); list.add("apple"); list.add("banana"); list.add("orange");

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3. Use HashSet to create a collection and initialize the data:

   import java.util.HashSet; HashSet set = new HashSet(); set.add("apple"); set.add("banana"); set.add("orange");

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2. Adding a collection
Add elements to the collection The operation uses the add() method, and we can use the methods provided by the collection to add elements. The following are several common operations:

1. Add elements to ArrayList:

   list.add("mango"); list.add(2, "grape");

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2. Add elements to LinkedList:

   list.add("mango"); list.addFirst("strawberry");

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3. Add elements to HashSet:

   set.add("mango"); set.add("grape");

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3. Set deletion operation
To delete elements in the set, use the remove() method, through Specifies the element to delete. The following are several common deletion operations:

1. Delete elements from ArrayList:

   list.remove("apple"); list.remove(1);

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2. Delete elements from LinkedList:

   list.remove("apple"); list.removeFirst();

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3. Delete elements from HashSet:

   set.remove("apple");

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4. Collection modification operation
The modification operation of the collection needs to be modified through the index or the specified element. The following are several common modification operations:

1. Modify elements in ArrayList:

   list.set(0, "pear");

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2. Modify elements in LinkedList:

   list.set(1, "pear");

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3. Modify elements in HashSet (HashSet does not support modification operations, you need to delete them first and then add them):

   set.remove("apple"); set.add("pear");

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5. Set query operations
Collection query operations can be performed by index or specified elements. The following are several common query operations:

1. Query elements in ArrayList:

   String element = list.get(0);

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2. Query elements in LinkedList:

   String element = list.get(1);

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3. Query elements in HashSet (HashSet has no index and needs to be queried through iterators):

   Iterator iterator = set.iterator(); while (iterator.hasNext()) { String element = iterator.next(); // 进行元素的操作 }

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Conclusion:
This article introduces how Use Java collection framework functions to add, delete, modify, and query collections. Through these operations, we can easily perform corresponding operations on the collection. Addition, deletion, modification and query of collections are common operations in Java development. Mastering these operations can improve the efficiency and readability of the code. I hope this article can help readers better understand and use collection framework functions.

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