在现实情况中，我们会遇到这样的情况，从后台服务器拿到的数据是一个一维数组，但是我们显示的时候要分类显示（如：需要按照月份来分类显示列表），这个时候就需要把一维数组转换为二维数组，方便我们将数据显示出来。如果每一次都重新写转换的方法细节，那将浪费很多时间在重复的代码上面。
后面为了省时间，就花了半天时间，写出来下面的工具类，方便数据转换为所需的格式，同时进行数据排序。
下面先把代码放出来：
1.编写一个List，Set，Map转换的帮助类（CollectionUtils）
public class CollectionUtils {
/**
* List转set
*
* @param list
* @param <T>
* @return
*/
public static <T> Set<T> getSetByList(List<T> list) {
Set<T> result = new HashSet<>(list);
return result;
}
/**
* set转list
*
* @param setArrs
* @param <T>
* @return
*/
public static <T> List<T> getListBySet(Set<T> setArrs) {
ArrayList<T> result = new ArrayList<T>(setArrs);
return result;
}
/**
* map转list，不排序
*
* @param map
* @param <K>
* @param <V>
* @return
*/
public static <K, V> List<V> getListByMap(Map<K, V> map) {
return getListByMap(map, null);
}
/**
* map转list，排序
*
* @param map
* @param <K>
* @param <V>
* @return
*/
public static <K, V> List<V> getListByMap(Map<K, V> map, Comparator<V> comparator) {
ArrayList<V> result = new ArrayList<V>();
for (V value : map.values()) {
result.add(value);
}
if (comparator != null) {
//进行排序
Collections.sort(result, comparator);
}
return result;
}
/**
* list转map，key为Integer，不排序
*
* @param list
* @param <V>
* @return
*/
public static <V> Map<Integer, V> getMapByList(List<V> list) {
return getMapByList(list, null);
}
/**
* list转map，key为Integer，排序
*
* @param list
* @param <V>
* @return
*/
public static <V> Map<Integer, V> getMapByList(List<V> list, Comparator<V> comparator) {
if (comparator != null) {
//进行排序
Collections.sort(list, comparator);
}
if (list != null && list.size() > 0) {
Map<Integer, V> result = new HashMap<>();
for (int i = 0; i < list.size(); i++) {
result.put(i, list.get(i));
}
return result;
}
return null;
}
}
2.编写静态帮助类（AbsTwoDimensionalArrayUtils）
public abstract class AbsTwoDimensionalArrayUtils<K, V> {
//升序（从小到大）
public static final int ASC_TYPE = 0;
//降序（从大到小）
public static final int DESC_TYPE = 1;
protected Class<K> kClass;
public AbsTwoDimensionalArrayUtils(Class<K> kClass) {
this.kClass = kClass;
}
/**
* 获取排序后的二维数组
*
* @param dataArrays
* @return
*/
public List<List<V>> getTwoDimensionalArrayByList(List<V> dataArrays) {
Map<K, List<V>> mapByList = getMapByList(dataArrays);
List<List<V>> result = null;
//排序小组的顺序
Comparator<Map.Entry<K, List<V>>> keyComparator = getKeyListComparator();
if (keyComparator != null) {
result = new ArrayList<>();
List<Map.Entry<K, List<V>>> list = new ArrayList<Map.Entry<K, List<V>>>(mapByList.entrySet());
Collections.sort(list, keyComparator);
for (int i = 0; i < list.size(); i++) {
result.add(list.get(i).getValue());
}
System.out.println("end time " + System.currentTimeMillis());
} else {
//直接转换
result = CollectionUtils.getListByMap(mapByList);
}
return result;
}
/**
* 获取HashMap
*
* @param dataArrays
* @return
*/
public Map<K, List<V>> getMapByList(List<V> dataArrays) {
System.out.println("start time " + System.currentTimeMillis());
HashMap<K, List<V>> result = new HashMap<K, List<V>>();
if (dataArrays != null && dataArrays.size() > 0) {
K key;
for (int i = 0; i < dataArrays.size(); i++) {
V v = dataArrays.get(i);
key = getKey(v);
List<V> value;
if (result.containsKey(key)) {
//如果已经有了，就取出来
value = result.get(key);
value.add(v);
} else {
value = new ArrayList<>();
value.add(v);
}
result.put(key, value);
}
}
//排序每个组里面的数据
Comparator<V> valuecomparator = getValueListComparator();
if (valuecomparator != null) {
List<V> mapListValue;
for (Map.Entry<K, List<V>> entry : result.entrySet()) {
mapListValue = entry.getValue();
if (mapListValue != null && mapListValue.size() > 0) {
Collections.sort(mapListValue, valuecomparator);
}
}
}
System.out.println("end time " + System.currentTimeMillis());
return result;
}
/**
* 通过V来实现分组
*
* @param v
* @return
*/
public abstract K getKey(V v);
/**
* 编写key的排序
* @return
*/
public abstract Comparator<Map.Entry<K, List<V>>> getKeyListComparator();
/**
* 编写value的排序规则
*
* @return
*/
public abstract Comparator<V> getValueListComparator();
}
3.根据静态帮助类编写key为int和String的帮助类
A.key为Int时
public abstract class AbsIntTwoDimensionalArrayUtils<V> extends AbsTwoDimensionalArrayUtils<Integer, V> {
protected Class<V> vClass;
protected Field field;
protected Method method;
protected Field sortField;
protected Method sortMethod;
public AbsIntTwoDimensionalArrayUtils(Class vClass) {
super(Integer.class);
this.vClass = vClass;
String mapName = getMapKeyName();
String sortName = getSortName();
//获取分类字段
try {
field = vClass.getField(mapName);
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
//获取排序字段
try {
sortField = vClass.getField(sortName);
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
//获取分类的字段的值的method
try {
String firstLetter = mapName.substring(0, 1).toUpperCase();
String getter = "get" + firstLetter + mapName.substring(1);
method = vClass.getMethod(getter, new Class[]{});
} catch (Exception e) {
e.printStackTrace();
}
//获取排序的字段的值的method
try {
String firstLetterSort = sortName.substring(0, 1).toUpperCase();
String getter = "get" + firstLetterSort + sortName.substring(1);
sortMethod = vClass.getMethod(getter, new Class[]{});
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public Integer getKey(V v) {
if (field == null) {
//说明是字段不为public，去寻找get方法
try {
return (Integer) method.invoke(v, new Integer[]{});
} catch (Exception ex) {
ex.printStackTrace();
}
} else {
try {
return field.getInt(v);
} catch (Exception e) {
e.printStackTrace();
}
}
return 0;
}
@Override
public Comparator<Map.Entry<Integer, List<V>>> getKeyListComparator() {
return new Comparator<Map.Entry<Integer, List<V>>>() {
@Override
public int compare(Map.Entry<Integer, List<V>> o1, Map.Entry<Integer, List<V>> o2) {
if (getMapKeySortType() == ASC_TYPE) {
return ascMapKey(o1, o2);
} else {
return descMapkey(o1, o2);
}
}
};
}
/**
* 根据map的key降序排序
*
* @param o1
* @param o2
* @return
*/
private Integer descMapkey(Map.Entry<Integer, List<V>> o1, Map.Entry<Integer, List<V>> o2) {
try {
if (o1.getKey() > o2.getKey()) {
return -1;
}
if (o1.getKey() < o2.getKey()) {
return 1;
}
} catch (Exception e) {
e.printStackTrace();
}
return 0;
}
/**
* 根据map的key升序排序
*
* @param o1
* @param o2
* @return
*/
private Integer ascMapKey(Map.Entry<Integer, List<V>> o1, Map.Entry<Integer, List<V>> o2) {
try {
if (o1.getKey() < o2.getKey()) {
return -1;
}
if (o1.getKey() > o2.getKey()) {
return 1;
}
} catch (Exception e) {
e.printStackTrace();
}
return 0;
}
@Override
public Comparator<V> getValueListComparator() {
return new Comparator<V>() {
@Override
public int compare(V o1, V o2) {
if (getSortType() == ASC_TYPE) {
return sortAsc(o1, o2);
} else {
return sortDesc(o1, o2);
}
}
};
}
/**
* 降序排序每个子对象
*
* @param o1
* @param o2
* @return
*/
private int sortDesc(V o1, V o2) {
if (sortField == null) {
try {
if (isIntSortFiled()) {
return ((Integer) sortMethod.invoke(o2, new Integer[]{})).compareTo((Integer) sortMethod.invoke(o1, new Integer[]{}));
} else {
return ((String) sortMethod.invoke(o2, new String[]{})).compareTo((String) sortMethod.invoke(o1, new String[]{}));
}
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
} else {
try {
if (isIntSortFiled()) {
if (sortField.getInt(o1) > sortField.getInt(o2)) {
return -1;
}
if (sortField.getInt(o1) < sortField.getInt(o2)) {
return 1;
}
} else {
return ((String) sortField.get(o2)).compareTo((String) sortField.get(o1));
}
} catch (Exception e) {
e.printStackTrace();
}
}
return 0;
}
/**
* 升序排序每个子对象
*
* @param o1
* @param o2
* @return
*/
private int sortAsc(V o1, V o2) {
if (sortField == null) {
try {
if (isIntSortFiled()) {
return ((Integer) sortMethod.invoke(o1, new Integer[]{})).compareTo((Integer) sortMethod.invoke(o2, new Integer[]{}));
} else {
return ((String) sortMethod.invoke(o1, new String[]{})).compareTo((String) sortMethod.invoke(o2, new String[]{}));
}
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
} else {
try {
if (isIntSortFiled()) {
if (sortField.getInt(o1) > sortField.getInt(o2)) {
return 1;
}
if (sortField.getInt(o1) < sortField.getInt(o2)) {
return -1;
}
} else {
return ((String) sortField.get(o1)).compareTo((String) sortField.get(o2));
}
} catch (Exception e) {
e.printStackTrace();
}
}
return 0;
}
/**
* 获取对象的排序字段名
*
* @return
*/
public abstract String getSortName();
/**
* 获取map的key字段名
*
* @return
*/
public abstract String getMapKeyName();
/**
* 获取每个对象的排序方式（升序/降序）
*
* @return
*/
public abstract int getSortType();
/**
* 获取map的key的排序方式（升序/降序）
*
* @return
*/
public abstract int getMapKeySortType();
/**
* 对象的字段是否是int类型的排序字段
*
* @return
*/
public abstract boolean isIntSortFiled();
}
B.key为String时
public abstract class AbsStringTwoDimensionalArrayUtils<V> extends AbsTwoDimensionalArrayUtils<String, V> {
protected Class<V> vClass;
protected Field field;
protected Method method;
protected Field sortField;
protected Method sortMethod;
public AbsStringTwoDimensionalArrayUtils(Class vClass) {
super(String.class);
this.vClass = vClass;
String mapName = getMapKeyName();
String sortName = getSortName();
//获取分类字段
try {
field = vClass.getField(mapName);
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
//获取排序字段
try {
sortField = vClass.getField(sortName);
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
//获取分类的字段的值的method
try {
String firstLetter = mapName.substring(0, 1).toUpperCase();
String getter = "get" + firstLetter + mapName.substring(1);
method = vClass.getMethod(getter, new Class[]{});
} catch (Exception e) {
e.printStackTrace();
}
//获取排序的字段的值的method
try {
String firstLetterSort = sortName.substring(0, 1).toUpperCase();
String getter = "get" + firstLetterSort + sortName.substring(1);
sortMethod = vClass.getMethod(getter, new Class[]{});
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public String getKey(V v) {
if (field == null) {
//说明是字段不为public，去寻找get方法
try {
return (String) method.invoke(v, new String[]{});
} catch (Exception ex) {
ex.printStackTrace();
}
} else {
try {
return (String) field.get(v);
} catch (Exception e) {
e.printStackTrace();
}
}
return "";
}
@Override
public Comparator<Map.Entry<String, List<V>>> getKeyListComparator() {
return new Comparator<Map.Entry<String, List<V>>>() {
@Override
public int compare(Map.Entry<String, List<V>> o1, Map.Entry<String, List<V>> o2) {
if (getMapKeySortType() == ASC_TYPE) {
return ascMapKey(o1, o2);
} else {
return descMapkey(o1, o2);
}
}
};
}
/**
* 根据map的key降序排序
*
* @param o1
* @param o2
* @return
*/
private Integer descMapkey(Map.Entry<String, List<V>> o1, Map.Entry<String, List<V>> o2) {
try {
return o2.getKey().compareTo(o1.getKey());
} catch (Exception e) {
e.printStackTrace();
}
return 0;
}
/**
* 根据map的key升序排序
*
* @param o1
* @param o2
* @return
*/
private Integer ascMapKey(Map.Entry<String, List<V>> o1, Map.Entry<String, List<V>> o2) {
try {
return o1.getKey().compareTo(o2.getKey());
} catch (Exception e) {
e.printStackTrace();
}
return 0;
}
@Override
public Comparator<V> getValueListComparator() {
return new Comparator<V>() {
@Override
public int compare(V o1, V o2) {
if (getSortType() == ASC_TYPE) {
return sortAsc(o1, o2);
} else {
return sortDesc(o1, o2);
}
}
};
}
/**
* 降序排序每个子对象
*
* @param o1
* @param o2
* @return
*/
private int sortDesc(V o1, V o2) {
if (sortField == null) {
try {
if (isIntSortFiled()) {
return ((Integer) sortMethod.invoke(o2, new Integer[]{})).compareTo((Integer) sortMethod.invoke(o1, new Integer[]{}));
} else {
return ((String) sortMethod.invoke(o2, new String[]{})).compareTo((String) sortMethod.invoke(o1, new String[]{}));
}
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
} else {
try {
if (isIntSortFiled()) {
if (sortField.getInt(o1) > sortField.getInt(o2)) {
return -1;
}
if (sortField.getInt(o1) < sortField.getInt(o2)) {
return 1;
}
} else {
return ((String) sortField.get(o2)).compareTo((String) sortField.get(o1));
}
} catch (Exception e) {
e.printStackTrace();
}
}
return 0;
}
/**
* 升序排序每个子对象
*
* @param o1
* @param o2
* @return
*/
private int sortAsc(V o1, V o2) {
if (sortField == null) {
try {
if (isIntSortFiled()) {
return ((Integer) sortMethod.invoke(o1, new Integer[]{})).compareTo((Integer) sortMethod.invoke(o2, new Integer[]{}));
} else {
return ((String) sortMethod.invoke(o1, new String[]{})).compareTo((String) sortMethod.invoke(o2, new String[]{}));
}
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
} else {
try {
if (isIntSortFiled()) {
if (sortField.getInt(o1) > sortField.getInt(o2)) {
return 1;
}
if (sortField.getInt(o1) < sortField.getInt(o2)) {
return -1;
}
} else {
return ((String) sortField.get(o1)).compareTo((String) sortField.get(o2));
}
} catch (Exception e) {
e.printStackTrace();
}
}
return 0;
}
/**
* 获取对象的排序字段名
*
* @return
*/
public abstract String getSortName();
/**
* 获取map的key字段名
*
* @return
*/
public abstract String getMapKeyName();
/**
* 获取每个对象的排序方式（升序/降序）
*
* @return
*/
public abstract int getSortType();
/**
* 获取map的key的排序方式（升序/降序）
*
* @return
*/
public abstract int getMapKeySortType();
/**
* 对象的字段是否是int类型的排序字段
*
* @return
*/
public abstract boolean isIntSortFiled();
}
----------------------------------------华丽的分割线----------------------------------------------------------
下面就到了万众期待的使用方式了：
1.根据实际的数据类型，来定义帮助类，如果key是Int，就继承AbsIntTwoDimensionalArrayUtils；如果key是String，就继承AbsStringTwoDimensionalArrayUtils。
下面使用了int类型的例子：
public class TwoDimensionalArrayDemoUtils
extends AbsIntTwoDimensionalArrayUtils<User> {
public TwoDimensionalArrayDemoUtils() {
super(User.class);
}
@Override
public String getSortName() {
return "name";
}
@Override
public int getSortType() {
return ASC_TYPE;
}
@Override
public int getMapKeySortType() {
return ASC_TYPE;
}
@Override
public String getMapKeyName() {
return "age";
}
@Override
public boolean isIntSortFiled() {
return false;
}
}
2.数据类型User类如下：
public class User {
public int id;
private int age;
public String name = "";
public User(int id, int age, String name) {
this.id = id;
this.age = age;
this.name = name;
}
public int getAge() {
return age;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
}
3.调用方式
TwoDimensionalIntArrayDemoUtils hashMapUtils = new TwoDimensionalIntArrayDemoUtils();
//获取二维数组
List<List<User>> lists = hashMapUtils.getTwoDimensionalArrayByList(users);
//获取HashMap
Map<Integer, List<User>> mapByList = hashMapUtils.getMapByList(users);
这样操作下来，我们就可以将一个一维数组转换为一个二维数组或者一个Map结构的数据，同时将数据进行排序排序。
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