• 对List对象按照某个成员变量进行排序


    /**
         * 对List对象按照某个成员变量进行排序
         * @param list       List对象
         * @param sortField  排序的属性名称
         * @param sortMode   排序方式:ASC,DESC 任选其一
         */
        public static <T> void sortList(List<T> list, final String sortField, final String sortMode) {
            Collections.sort(list, new Comparator<T>() {
                @Override
                public int compare(T o1, T o2) {
                    try {
                        Class clazz = o1.getClass();
                        Field field = clazz.getDeclaredField(sortField); //获取成员变量
                        field.setAccessible(true); //设置成可访问状态
                        String typeName = field.getType().getName().toLowerCase(); //转换成小写
    
                        Object v1 = field.get(o1); //获取field的值
                        Object v2 = field.get(o2); //获取field的值
    
                        boolean ASC_order = (sortMode == null || "ASC".equalsIgnoreCase(sortMode));
    
                        //判断字段数据类型,并比较大小
                        if(typeName.endsWith("string")) {
                            String value1 = v1.toString();
                            String value2 = v2.toString();
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("short")) {
                            Short value1 = Short.parseShort(v1.toString());
                            Short value2 = Short.parseShort(v2.toString());
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("byte")) {
                            Byte value1 = Byte.parseByte(v1.toString());
                            Byte value2 = Byte.parseByte(v2.toString());
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("char")) {
                            Integer value1 = (int)(v1.toString().charAt(0));
                            Integer value2 = (int)(v2.toString().charAt(0));
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("int") || typeName.endsWith("integer")) {
                            Integer value1 = Integer.parseInt(v1.toString());
                            Integer value2 = Integer.parseInt(v2.toString());
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("long")) {
                            Long value1 = Long.parseLong(v1.toString());
                            Long value2 = Long.parseLong(v2.toString());
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("float")) {
                            Float value1 = Float.parseFloat(v1.toString());
                            Float value2 = Float.parseFloat(v2.toString());
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("double")) {
                            Double value1 = Double.parseDouble(v1.toString());
                            Double value2 = Double.parseDouble(v2.toString());
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("boolean")) {
                            Boolean value1 = Boolean.parseBoolean(v1.toString());
                            Boolean value2 = Boolean.parseBoolean(v2.toString());
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("date")) {
                            Date value1 = (Date)(v1);
                            Date value2 = (Date)(v2);
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else if(typeName.endsWith("timestamp")) {
                            Timestamp value1 = (Timestamp)(v1);
                            Timestamp value2 = (Timestamp)(v2);
                            return ASC_order ? value1.compareTo(value2) : value2.compareTo(value1);
                        }
                        else {
                            //调用对象的compareTo()方法比较大小
                            Method method = field.getType().getDeclaredMethod("compareTo", new Class[]{field.getType()});
                            method.setAccessible(true); //设置可访问权限
                            int result  = (Integer)method.invoke(v1, new Object[]{v2});
                            return ASC_order ? result : result*(-1);
                        }
                    }
                    catch (Exception e) {
                        String err = e.getLocalizedMessage();
                        System.out.println(err);
                        e.printStackTrace();
                    }
    
                    return 0; //未知类型,无法比较大小
                }
            });
        }
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  • 原文地址:https://www.cnblogs.com/hacjy/p/5124969.html
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