java集合中寻找指定对象的集合或对象数据

package com.xiniunet.web.tool;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.HashSet;import java.util.List;import java.util.Set;/** * Created by xn on 15/7/22. */public class ListUtil { /** * 判断集合中是否存在该对象的数据 * @param list * @param value * @param <T> * @return 返回在集合中首次匹配到的对象数据 */ public static <T> T matchObject(List<T> list,T value) { if(list == null || list.size() == 0 || value == null){ return null; } for(T t : list) { if(value.equals(t)){ return t; } } return null; } /** * 判断集合中是否存在该长整型数值的数据对象 * @param list * @param id * @param <T> * @return 返回首次符合长整型数值的数据对象 */ public static <T> T matchObject(List<T> list,Long id) { if(list == null || list.size() == 0 || id == null){ return null; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("getId"); } catch (NoSuchMethodException e) { e.printStackTrace(); } for(T t : list) { try { if(id.equals(method.invoke(t))){ return t; } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } return null; } /** * 判断集合中是否存在该长整型数值的数据对象 * @param list * @param id * @param <T> * @return 返回符合长整型数值的数据集合对象 */ public static <T> List<T> matchList(List<T> list,Long id) { List<T> result = new ArrayList(); if(list == null || list.size() == 0 || id == null){ return result; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("getId"); } catch (NoSuchMethodException e) { e.printStackTrace(); } for(T t : list) { try { if(id.equals(method.invoke(t))){ result.add(t); } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } return result; } /** * 判断集合中是否存在该长整型数据集合的集合数据 * @param list * @param ids * @param <T> * @return 返回符合长整型数值的数据集合对象 */ public static <T> List<T> matchList(List<T> list,List<Long> ids) { List<T> result = new ArrayList(); if(list == null || list.size() == 0 || ids == null || ids.size() == 0){ return result; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("getId"); } catch (NoSuchMethodException e) { e.printStackTrace(); } for(Long id : ids){ for(T t : list) { try { if(id.equals(method.invoke(t))){ result.add(t); } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } } return result; } /** * 循环判断集合中是否存在长整型数据集合中的数据(每个对象只匹配第一次取到的值) * @param list * @param ids * @param <T> * @return 返回符合长整型数据集合中的集合对象(每个对象只匹配第一次取到的值) */ public static <T> List<T> matchBatchObject(List<T> list,List<Long> ids) { List<T> result = new ArrayList(); if(list == null || list.size() == 0 || ids == null || ids.size() == 0){ return result; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("getId"); } catch (NoSuchMethodException e) { e.printStackTrace(); } for(Long id :ids){ for(T t : list) { try { if(id.equals(method.invoke(t))){ result.add(t); break; } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } } return result; } /** * 判断集合中是否存在该对象相匹配的对象数据 * @param list * @param fieldName * @param id * @param <T> * @param <K> * @return 返回符合对象相匹配的对象数据 */ public static <T,K> T matchObject(List<T> list,String fieldName,K id) { if(list == null || list.size() == 0 || id == null){ return null; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("get" + Character.isUpperCase(fieldName.charAt(0))); } catch (NoSuchMethodException e) { e.printStackTrace(); } for(T t : list) { try { if(id.equals(method.invoke(t))){ return t; } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } return null; } /** * 判断集合中是否存在该对象相匹配的对象数据 * @param list * @param fieldName * @param id * @param <T> * @param <K> * @return 返回符合对象相匹配的集合对象 */ public static <T,K> List<T> matchList(List<T> list,String fieldName,K id) { List<T> result = new ArrayList(); if(list == null || list.size() == 0 || id == null){ return result; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("get" + Character.isUpperCase(fieldName.charAt(0))); } catch (NoSuchMethodException e) { e.printStackTrace(); } for(T t : list) { try { if(id.equals(method.invoke(t))){ result.add(t); } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } return result; } /** * 循环判断集合中是否存在该对象相匹配的对象数据 * @param list * @param fieldName * @param ids * @param <T> * @param <K> * @return 返回符合对象相匹配的集合对象 */ public static <T,K> List<T> matchList(List<T> list,String fieldName,List<K> ids) { List<T> result = new ArrayList(); if(list == null || list.size() == 0 || ids == null || ids.size() == 0){ return result; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("get" + Character.isUpperCase(fieldName.charAt(0))); } catch (NoSuchMethodException e) { e.printStackTrace(); } for(K id : ids){ for(T t : list) { try { if(id.equals(method.invoke(t))){ result.add(t); } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } } return result; } /** * 判断集合中是否存在该对象相匹配的对象数据(每个对象只匹配第一次取到的值) * @param list * @param fieldName * @param ids * @param <T> * @param <K> * @return 返回符合对象相匹配的集合对象(每个对象只匹配第一次取到的值) */ public static <T,K> List<T> matchBatchObject(List<T> list,String fieldName,List<K> ids) { List<T> result = new ArrayList(); if(list == null || list.size() == 0 || ids == null || ids.size() == 0){ return result; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("get" + Character.isUpperCase(fieldName.charAt(0))); } catch (NoSuchMethodException e) { e.printStackTrace(); } for(K id :ids){ for(T t : list) { try { if(id.equals(method.invoke(t))){ result.add(t); break; } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } } return result; } public static <T> List<Long> getKeyList(List<T> list) { List<Long> result = new ArrayList(); if(list == null || list.size() == 0){ return result; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("getId"); } catch (NoSuchMethodException e) { e.printStackTrace(); } Set<Long> set = new HashSet<>(); for(T t : list) { try { Long id = (Long)method.invoke(t); if(id != null){ set.add(id); } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } for(Long id : set){ result.add(id); } return result; } public static <T,K> List<K> getKeyList(List<T> list,String fieldName) { List<K> result = new ArrayList(); if(list == null || list.size() == 0){ return result; } Class clazz = list.get(0).getClass(); Method method = null; try { method = clazz.getMethod("get" + Character.isUpperCase(fieldName.charAt(0))); } catch (NoSuchMethodException e) { e.printStackTrace(); } Set<K> set = new HashSet<>(); for(T t : list) { try { K k = (K)method.invoke(t); if(k != null){ set.add(k); } } catch (IllegalAccessException | InvocationTargetException e) { e.printStackTrace(); } } for(K k : set){ result.add(k); } return result; }}

转载于:https://www.cnblogs.com/Dream-Lasting/p/10167408.html