java排序接口Comparable 的实现与使用

java集合排序

一、map集合的排序

比较value进行排序

		List lastEventCauselist = new ArrayList();
		List lastNumlist = new ArrayList();
        HashMap map = new HashMap();
        for(int i=0;i o2.getAge()){
                    return 1;
                }
                if(o1.getAge() == o2.getAge()){
                    return 0;
                }
                return -1;
            }
        }); 
        System.out.println("排序后："+list);
    }
}

	public List removeExtra(List list) {
		List newList= new ArrayList();
        HashMap hashMap = new HashMap();
        for (CheckAdvice checkAdvice : list) {
            if (checkAdvice == null) {
                continue;
            }
            String  adviceId = checkAdvice.getAdviceId();
            if (adviceId != null) {
                String value = hashMap.get(adviceId);
                if (StringUtil.isEmpty(value)) { //如果value是空的  说明取到的这个adviceId是第一次取到
                    hashMap.put(adviceId, adviceId);
                    newList.add(checkAdvice); 
                } else {
                    continue;
                }
            }   
        }
        hashMap.clear();
        return newList;
	}

根据实体类中的某一字段进行排序

实体类实现Comparable 接口，仅仅对集合中某个字段通过递归二次遍历，不影响整体查询返回结果的逻辑性。

import java.io.Serializable;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

import com.cnten.platform.framework.web.dict.DictContext;
import com.github.pagehelper.util.StringUtil;

public class CheckAdvice implements Serializable,Comparable {

	private static final long serialVersionUID = 6674013991838914395L;
	private String adviceId;

	private String columnId;

	private String columnName;

	private String title;

	private String profile;

	private String contentFrom;

	private String oriLink;

	private String isReco;

	private String isRecoName;
	
	private String newsDate;

	private String isWork;

	private String isWorkName;

	private String skipMode;
	
	private String useLink;
	
	private String commentTotal;
	
	private String viewTotal;
	private String pointTotal;
	private String messageStatus;
	
	private String attachmentId;
	
	private String itemCode;
	private String itemName;
	private String href;
	private String companyId;
	private String companyName;
	
	private String blockCode;
	
	private String duration;
	private String createTime;
	public String getAdviceId() {
		return adviceId;
	}

	public void setAdviceId(String adviceId) {
		this.adviceId = adviceId;
	}

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

	public String getProfile() {
		return profile;
	}

	public void setProfile(String profile) {
		this.profile = profile;
	}

	public String getContent() {
		return content;
	}

	public void setContent(String content) {
		this.content = content;
	}

	public String getContentFrom() {
		return contentFrom;
	}

	public void setContentFrom(String contentFrom) {
		this.contentFrom = contentFrom;
	}

	public String getOriLink() {
		return oriLink;
	}

	public void setOriLink(String oriLink) {
		this.oriLink = oriLink;
	}

	public String getIsReco() {
		return isReco;
	}

	public void setIsReco(String isReco) {
		this.isReco = isReco;
	}

	public String getIsWork() {
		return isWork;
	}

	public void setIsWork(String isWork) {
		this.isWork = isWork;
	}

	public String getColumnId() {
		return columnId;
	}

	public void setColumnId(String columnId) {
		this.columnId = columnId;
	}

	public String getSkipMode() {
		return skipMode;
	}

	public void setSkipMode(String skipMode) {
		this.skipMode = skipMode;
	}

	public String getColumnName() {
		return columnName;
	}

	public void setColumnName(String columnName) {
		this.columnName = columnName;
	}

	public String getIsRecoName() {
		isRecoName = "";
		String dictItemName = DictContext.getInstance().getDict("whether", isReco);
		if (StringUtil.isNotEmpty(dictItemName))
			isRecoName = dictItemName;
		return isRecoName;
	}

	public void setIsRecoName(String isRecoName) {
		this.isRecoName = isRecoName;
	}

	public String getIsWorkName() {

		isWorkName = "";
		String dictItemName = DictContext.getInstance().getDict("whether", isWork);
		if (StringUtil.isNotEmpty(dictItemName))
			isWorkName = dictItemName;
		return isWorkName;
	}

	public void setIsWorkName(String isWorkName) {
		this.isWorkName = isWorkName;
	}

	public String getUseLink() {
		return useLink;
	}

	public void setUseLink(String useLink) {
		this.useLink = useLink;
	}

	public String getCommentTotal() {
		return commentTotal;
	}

	public void setCommentTotal(String commentTotal) {
		this.commentTotal = commentTotal;
	}

	public String getViewTotal() {
		return viewTotal;
	}

	public void setViewTotal(String viewTotal) {
		this.viewTotal = viewTotal;
	}

	public String getPointTotal() {
		return pointTotal;
	}

	public void setPointTotal(String pointTotal) {
		this.pointTotal = pointTotal;
	}

	public String getMessageStatus() {
		return messageStatus;
	}

	public void setMessageStatus(String messageStatus) {
		this.messageStatus = messageStatus;
	}

	public String getAttachmentId() {
		return attachmentId;
	}

	public void setAttachmentId(String attachmentId) {
		this.attachmentId = attachmentId;
	}

	public String getItemCode() {
		return itemCode;
	}

	public void setItemCode(String itemCode) {
		this.itemCode = itemCode;
	}

	public String getItemName() {
		return itemName;
	}

	public void setItemName(String itemName) {
		this.itemName = itemName;
	}
    
	public String getNewsDate() {
		return newsDate;
	}

	public void setNewsDate(String newsDate) {
		this.newsDate = newsDate;
	}

	public String getHref() {
		return href;
	}

	public String getCompanyId() {
		return companyId;
	}

	public void setCompanyId(String companyId) {
		this.companyId = companyId;
	}

	public String getCompanyName() {
		return companyName;
	}

	public void setCompanyName(String companyName) {
		this.companyName = companyName;
	}

	public String getBlockCode() {
		return blockCode;
	}

	public void setBlockCode(String blockCode) {
		this.blockCode = blockCode;
	}

	public String getDuration() {
		return duration;
	}

	public void setDuration(String duration) {
		this.duration = duration;
	}

	public String getCreateTime() {
		return createTime;
	}

	public void setCreateTime(String createTime) {
		this.createTime = createTime;
	}

	@Override
	public int compareTo(CheckAdvice ca) {
		DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
		try {
			 return df.parse(ca.getNewsDate()).compareTo(df.parse(this.getNewsDate()));
		} catch (ParseException e) {
			return 0;
		}
	}
	
} 		

	public List getHomePageData(String blockCode,String companyId) {
		List dataList = checkAdviceMapper.getHomePageData(blockCode,companyId);
		Collections.sort(dataList);
		return dataList;
	}