list根据对象属性去重

拼搏现实的明天。 2023-09-26 17:45 64阅读 0赞

1.建测试用实体类,重写equels

public class Cssp {
        
        private String spdm;
        private String spmc;
    
        public String getSpdm() {
        
            return spdm;
        }
    
        public void setSpdm(String spdm) {
        
            this.spdm = spdm;
        }
    
        public String getSpmc() {
        
            return spmc;
        }
    
        public void setSpmc(String spmc) {
        
            this.spmc = spmc;
        }
    
        public Cssp() {
        
        }
    
        public Cssp(String spdm, String spmc) {
        
            this.spdm = spdm;
            this.spmc = spmc;
        }
    
        @Override
        public String toString() {
        
            return "Cssp{" +
                    "spdm='" + spdm + '\'' +
                    ", spmc='" + spmc + '\'' +
                    '}';
        }
        @Override
        public boolean equals(Object o) {
        
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
    
            Cssp cssp = (Cssp) o;
    
            if (!this.spmc.equals(cssp.spmc)) return false;
            return this.spdm.equals(cssp.spdm);
    
        }
    
        @Override
        public int hashCode() {
        
            int result = this.spmc.hashCode();
            result = 31 * result + this.spdm.hashCode();
            return result;
        }
    }

2.插入测数据

Cssp cssp=new Cssp("spdm","111");
            Cssp cssp1=new Cssp("spdm","111");
            Cssp cssp2=new Cssp("spdm","222");
            Cssp cssp3=new Cssp("spdm","222");
            List<Cssp> list=Arrays.asList(cssp,cssp1,cssp2,cssp3);

3.Java8的方法

List<Cssp> j8List = new ArrayList<>();
            // 去重
            list.forEach(p -> {
        
                        if (!j8List.contains(p)) {
        
                            j8List.add(p);
                        }
                    }
            );

4.用set特性

ArrayList setList= new ArrayList();
            if (list.size() > 0) {
        
                Set set = new HashSet(list);
                setList.addAll(set);
            }

5.用新的list的

List<Cssp> xdlist = new ArrayList<>();
            for (Cssp cssp4 : list) {
        
                if (!xdlist.contains(cssp4)) {
        
                    xdlist.add(cssp4);
                }
            }
    	 System.out.println("java8去重："+j8List);
         System.out.println("set去重："+setList);
         System.out.println("新list去重："+xdlist);

![在这里插入图片描述][3e0c089fb4db42c09ba36d6c68aea875.png]

[3e0c089fb4db42c09ba36d6c68aea875.png]: https://img-blog.csdnimg.cn/3e0c089fb4db42c09ba36d6c68aea875.png