List里将某字段相同的元素合并

清疚 2022-12-13 04:58 337阅读 0赞

import java.util.ArrayList;
    import java.util.List;
    
    class A { 
        private String name;//姓名
        private int age;//年龄
        
        public String getName() { 
            return name;
        }
        public void setName(String name) { 
            this.name = name;
        }
        public int getAge() { 
            return age;
        }
        public void setAge(int age) { 
            this.age = age;
        }
    }
    public class Test4 { 
        
        public static void main(String[] args) { 
        List<A> oldList = new ArrayList<A>();//需要整合的List
        List<A> newList = new ArrayList<A>();//整合后的List
                A  aA = new A();
                aA.setName("a");
                aA.setAge(10);
                A  aB = new A();
                aB.setName("b");
                aB.setAge(20);
                A  aC = new A();
                aC.setName("c");
                aC.setAge(30);
                A  aD = new A();
                aD.setName("b");
                aD.setAge(40);
        
                oldList.add(aA);
                oldList.add(aB);
                oldList.add(aC);
                oldList.add(aD);
            for (A oldO : oldList) { 
                boolean flag = true;//给整合后集合添加子元素标志，true：添加，false:不添加，其年龄相加
                    for (A newO : newList) { 
                        if (newO.getName(). equals(oldO.getName())) { //判断姓名是否相同
                            newO.setAge(newO.getAge()+oldO.getAge());//姓名相同时，年龄相加
                            flag = false;
                        }
                    }
                if (flag) { 
                    newList.add(oldO);//给整合后集合添加子元素
                }
            }
            
            for (A a : newList) { //打印结果
                System.out.println(a.getName() + " : "+a.getAge());
            }
        }
    }