list.contains()方法判断是否包含自定义对象

我会带着你远行 2023-10-10 15:09 71阅读 0赞

**如果一个list中存入了许多user对象,如何使用contains方法判断该list是否包含某个对象呢?**

**首先list.contains()方法判断是否包含,需要在user中复写equals()方法**

**复写方法时需要确认如何认定user**

**比如俩个user的name属性相同,不管age和birthday是否相同,都认为这两个user是同一个user,那么我们在复写equals()方法时,只需要复写name字段的equals()方法**

**如果name和age俩个字段才能确定俩个user是否相同,那么就需要复写name和age这两个字段的equals()方法;**

**例如：**

public class JudgeNameDTO {
    
        /**维度编号**/
        private String extentCode;
    
        /**章节名称，或章节编号**/
        private String chapterCodeName;
    
        public JudgeNameDTO(String extentCode, String chapterCodeName) {
            this.extentCode = extentCode;
            this.chapterCodeName = chapterCodeName;
        }
    
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            JudgeNameDTO that = (JudgeNameDTO) o;
            return Objects.equals(extentCode, that.extentCode) && Objects.equals(chapterCodeName, that.chapterCodeName);
        }
    ｝

**重写了extentCode和chapterCodeName**

**判断：**

//检查数据是否符合规范
    List<JudgeNameDTO> judgeNameDTOSCode = new ArrayList<>();
    JudgeNameDTO judgeNameDTO = new JudgeNameDTO(ghaKbTitleExportDTO.getTitleCode(), ghaKbTitleExportDTO.getChapterTitle());
    if (judgeNameDTOSCode.contains(judgeNameDTO)){
         errorMsg.add(excelTitle + "表第" + (i+2) + "行”章节标题“内容重复！");
    }else {
         judgeNameDTOSCode.add(judgeNameDTO);
    }