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  • ArrayList中重复元素处理方法.[Java]

    1、使用HashSet删除ArrayList中重复的元素

    private static void sortByHashSet() {
            ArrayList<String> listWithDuplicateElements = new ArrayList<String>();
            listWithDuplicateElements.add("JAVA");        
            listWithDuplicateElements.add("J2EE");        
            listWithDuplicateElements.add("JSP");        
            listWithDuplicateElements.add("SERVLETS");        
            listWithDuplicateElements.add("JAVA");        
            listWithDuplicateElements.add("STRUTS");        
            listWithDuplicateElements.add("JSP");
            System.out.print("ArrayList With Duplicate Elements :");
            System.out.println(listWithDuplicateElements);
            HashSet<String> set = new HashSet<String>(listWithDuplicateElements);
            ArrayList<String> listWithoutDuplicateElements = new ArrayList<String>(set);
            System.out.print("ArrayList After Removing Duplicate Elements :");
            System.out.println(listWithoutDuplicateElements);
        }

    ArrayList With Duplicate Elements :[JAVA, J2EE, JSP, SERVLETS, JAVA, STRUTS, JSP]
    ArrayList After Removing Duplicate Elements :[SERVLETS, STRUTS, JSP, J2EE, JAVA]

    使用HashSet删除ArrayList中重复的元素
    注意输出结果。你会发现,在删除重复元素之后,元素重新洗牌。不再按照插入顺序排列

    2、使用LinkedHashSet删除ArrayList中重复的元素

    private static void sortByLinkedHashSet() {
            ArrayList<String> listWithDuplicateElements = new ArrayList<String>();
            listWithDuplicateElements.add("JAVA");        
            listWithDuplicateElements.add("J2EE");        
            listWithDuplicateElements.add("JSP");        
            listWithDuplicateElements.add("SERVLETS");        
            listWithDuplicateElements.add("JAVA");        
            listWithDuplicateElements.add("STRUTS");        
            listWithDuplicateElements.add("JSP");
            System.out.print("ArrayList With Duplicate Elements :");
            System.out.println(listWithDuplicateElements);
            LinkedHashSet<String> set = new LinkedHashSet<String>(listWithDuplicateElements);
            ArrayList<String> listWithoutDuplicateElements = new ArrayList<String>(set);
            System.out.print("ArrayList After Removing Duplicate Elements :");
            System.out.println(listWithoutDuplicateElements);        
        }

    ArrayList With Duplicate Elements :[JAVA, J2EE, JSP, SERVLETS, JAVA, STRUTS, JSP]
    ArrayList After Removing Duplicate Elements :[JAVA, J2EE, JSP, SERVLETS, STRUTS]

    使用LinkedHashSet删除ArrayList中重复的元素
    注意输出。你可以发现在删除ArrayList中的重复元素后,依然保持了元素的插入顺序

    英文原文连接 :http://javaconceptoftheday.com/how-to-remove-duplicate-elements-from-arraylist-in-java/

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  • 原文地址:https://www.cnblogs.com/Evelia/p/4703904.html
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