【Java】List

思维导航：

• 对List中map集合中某个字段排序
  • 升序排列
  • 方法1
  • 方法2
  • 方法3
  • 方法4
  • 结果
  • 降序排列
  • 工具类
  • 使用
  • 结果

 

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对List中map集合中某个字段排序

升序排列

方法1

Collections.sort(maps, new Comparator<Map<String, Object>>() {
    @Override
    public int compare(Map<String, Object> o1, Map<String, Object> o2) {
        return o1.get("createtime").toString().compareTo(o2.get("createtime").toString());
    }
});

方法2

maps.sort((o1, o2) -> o1.get("createtime").toString().compareTo(o2.get("createtime").toString()));

方法3

maps.sort(Comparator.comparing(o -> o.get("createtime").toString()));

方法4

工具类

• src/main/java/com/runsky/utils/MapComparatorAsc.java

package com.runsky.utils;
 
import java.util.Comparator;
import java.util.Map;
 
public class MapComparatorAsc implements Comparator<Map<String, Object>> {
    @Override
    public int compare(Map<String, Object> m1, Map<String, Object> m2) {
        Integer v1 = Integer.valueOf(m1.get("createtime").toString());
        Integer v2 = Integer.valueOf(m2.get("createtime").toString());
        if(v1 != null){
            return v1.compareTo(v2);
        }
        return 0;
    }
}

使用

• src/main/java/com/runsky/sys/controller/DiydataController.java

Collections.sort(maps, new MapComparatorAsc());

结果

降序排列

工具类

• src/main/java/com/runsky/utils/MapComparatorDesc.java

package com.runsky.utils;
 
import java.util.Comparator;
import java.util.Map;
 
public class MapComparatorDesc implements Comparator<Map<String, Object>> {
    @Override
    public int compare(Map<String, Object> m1, Map<String, Object> m2) {
        Integer v1 = Integer.valueOf(m1.get("createtime").toString());
        Integer v2 = Integer.valueOf(m2.get("createtime").toString());
        if (v2 != null) {
            return v2.compareTo(v1);
        }
        return 0;
    }
}

使用

• src/main/java/com/runsky/sys/controller/DiydataController.java

Collections.sort(maps, new MapComparatorDesc());

结果