1、List<Object>去重
People類
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public class People { private int id; private String name; private Date createDate; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getCreateDate() { return createDate; } public void setCreateDate(Date createDate) { this.createDate = createDate; } } |
main方法
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public static void main(String[] args) throws Exception{ List<People> list = new ArrayList<People>(); People p1 = new People(); p1.setId(1); p1.setName("趙"); list.add(p1); People p2 = new People(); p2.setId(2); p2.setName("錢"); list.add(p2); People p3 = new People(); p3.setId(3); p3.setName("孫"); list.add(p3); People p4 = new People(); p4.setId(4); p4.setName("李"); list.add(p4); People p5 = new People(); p5.setId(5); p5.setName("周"); list.add(p5); list.add(p1); for(People p : list){ System.out.println(p); } System.out.println("=========================="); Set<People> set = new HashSet<People>(list); list.clear(); list.addAll(new ArrayList<People>(set)); for(People p : list){ System.out.println(p); } } |
2、List<Object>按照日期字段排序
自定義Comparator
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public class MyComparator implements Comparator<People> { @Override public int compare(People p1, People p2) { return p1.getCreateDate().compareTo(p2.getCreateDate()); } } |
main方法
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public static void main(String[] args) throws Exception{ List<People> list = new ArrayList<People>(); People p1 = new People(); p1.setId(1); p1.setName("趙"); p1.setCreateDate(new Date(new Date().getTime() + 1000)); list.add(p1); People p2 = new People(); p2.setId(2); p2.setName("錢"); p2.setCreateDate(new Date(new Date().getTime() + 8000)); list.add(p2); People p3 = new People(); p3.setId(3); p3.setName("孫"); p3.setCreateDate(new Date(new Date().getTime() + 7000)); list.add(p3); People p4 = new People(); p4.setId(4); p4.setName("李"); p4.setCreateDate(new Date(new Date().getTime() + 5000)); list.add(p4); People p5 = new People(); p5.setId(5); p5.setName("周"); p5.setCreateDate(new Date(new Date().getTime() + 6000)); list.add(p5); for(People p : list){ System.out.println(p.getId()); } //1,2,3,4,5 System.out.println("======================="); Collections.sort(list, new MyComparator()); //1,4,5,3,2 for(People p : list){ System.out.println(p.getId()); } } |
以上這篇List對象去重和按照某個字段排序的實現方法就是小編分享給大家的全部內容了，希望能給大家一個參考，也希望大家多多支持服務器之家。
