List合并

素颜马尾好姑娘i 2021-12-03 19:15 254阅读 0赞

package cn.swsk.xbry.mess.controller;
    
    import java.lang.reflect.Field;
    import java.util.ArrayList;
    import java.util.Collection;
    import java.util.List;
    
    /**
     * List合并
     * @author css
     * @data 2019/7/11 15:28
     */
    public class JoinList<T> {
        private List<T> p;
        private List<?> c;
    
        private Field pf;
        private Field plf;
        private Field cf;
    
        private Field getField(Class<?> clazz, String name) {
            try {
                Field f = clazz.getDeclaredField(name);
                f.setAccessible(true);
                return f;
            } catch (NoSuchFieldException e) {
                e.printStackTrace();
            }
            return null;
        }
    
        public void setParent(List<T> p, String name, String children) {
            this.p = p;
            Class<?> clazz = p.get(0).getClass();
            this.pf = getField(clazz, name);
            this.plf = getField(clazz, children);
        }
    
        public void setChild(List<?> c, String name) {
            this.c = c;
            Class<?> clazz = c.get(0).getClass();
            this.cf = getField(clazz, name);
        }
    
        public List<?> join() throws IllegalAccessException, InstantiationException {
            for (T t: p) {
                Object pv = pf.get(t);
                for (Object o: c) {
                    Object cv = cf.get(o);
                    if(pv.equals(cv)){
                        Collection list = (Collection<?>) plf.get(t);
                        if(list == null){
                            list = new ArrayList();
                            list.add(o);
                            plf.set(t, list);
                        } else {
                            list.add(o);
                        }
                    }
                }
            }
            return this.p;
        }
    
        static class A{Integer id; String name;List<B> list;
    
            @Override
            public String toString() {
                return "A{" +
                        "id=" + id +
                        ", name='" + name + '\'' +
                        ", list=" + list +
                        '}';
            }
        }
        static class B{Integer pid; String name;
    
            @Override
            public String toString() {
                return "B{" +
                        "pid=" + pid +
                        ", name='" + name + '\'' +
                        '}';
            }
        }
        public static void main(String[] args) throws InstantiationException, IllegalAccessException {
            A a = new A();
            a.id = 3;
            a.name = "a";
    
            B b = new B();
            b.pid = 3 ;
            b.name = "b";
    
    
            List<A> al = new ArrayList<>();
            List<B> bl = new ArrayList<>();
            al.add(a);
            bl.add(b);
    
            JoinList<A> test = new JoinList<>();
            test.setParent(al, "id", "list");
            test.setChild(bl, "pid");
            System.out.println(test.join());
        }
    }

转载于:https://www.cnblogs.com/chenss15060100790/p/11170851.html