Question

这就是我到目前为止向下滚动到main并且你会看到//第7部分这是我必须做一个小循环包含搜索我的树的if语句的人，即在树集中以h开头的名字的人SP1

import java.util.*;

public class assignment8 {

    public static void main(String[] args) {

        //question1
        System.out.println(months.MARCH.season());
        System.out.println(months.SEPTEMBER.season());
        System.out.println("------------------");

        //question2
        TreeSet<Person> sp1 = new TreeSet<Person>(); //a set of people(person is the object)
        sp1.add(new Person("David"));
        sp1.add(new Person("Sarah"));
        sp1.add(new Person("BenDover"));
        sp1.add(new Person("Jack"));
        sp1.add(new Person("Mark"));
        System.out.println(sp1);
        TreeSet<Person> sp2 = new TreeSet<Person>(); //a set of people(person is the object)
        sp2.add(new Person("David"));
        sp2.add(new Person("Sarah"));
        sp2.add(new Person("Jess"));
        sp2.add(new Person("James"));
        sp2.add(new Person("Adam"));
        System.out.println(sp2);
        //part1
        System.out.println("Boolean:  "+sp1.containsAll(sp2));

        //part2
        TreeSet<Person> insp = new TreeSet<Person>(sp1);         
        insp.retainAll(sp2);         
        System.out.println("Intersection: " +insp); 

        //part3
        TreeSet<Person> unsp = new TreeSet<Person>(sp1);         
        unsp.addAll(sp2);         
        System.out.println("Union: " +unsp);

        //part4
        TreeSet<Person> diffsp = new TreeSet<Person>(sp1);         
        diffsp.removeAll(sp2);         
        System.out.println("Dfference in sp1 and sp2: " +diffsp);

        //part5 
        TreeSet<Person> diffsp1 = new TreeSet<Person>(sp2);         
        diffsp1.removeAll(sp1);         
        System.out.println("Dfference in sp2 and sp1: " +diffsp1);

        //part6
        System.out.print("Are diffsp & diffsp1 the same: "+diffsp.equals(diffsp1));

        //part7 
        for (Person current : sp1){ 
        if(current.charAt(0)=='m' || current.charAt(0)=='M'){
        System.out.println("Name begining with M:"+current.toString())


    }
}
//Question 1
enum Season {

      SPRING,SUMMER,AUTUMN,WINTER;

     public String toString(){
            switch(this){
            case SPRING:  
            return "Spring";
            case SUMMER:
            return "Summer";
            case AUTUMN:
            return "Autumn";
            default:
            return "WINTER";
            }
     } 
}
enum months {

    JANUARY,FEBUARY,MARCH,APRIL,MAY,JUNE,JULY,AUGUST,SEPTEMBER,OCTOBER,NOVEMBER,DECEMBER;

    public String toString(){
        switch(this){
        case JANUARY:
        return "January";
        case FEBUARY:
        return "Febuary";
        case MARCH:
        return "March";
        case APRIL:
        return "April";
        case MAY:
        return "May";
        case JUNE:
        return "June";
        case JULY:
        return "July";
        case AUGUST:
        return "August";
        case SEPTEMBER:
        return "September";
        case OCTOBER:
        return "October";
        case NOVEMBER:
        return "November";
        default:
        return "December";  
        }
    }
        public Season season(){
            int k = this.ordinal(); //gets a month and makes k == to the ordinal value of that month
            if (k == 0 || k == 10 || k ==11 )
                return Season.WINTER;
            else if (k==7 || k==8 || k==9)
                return Season.AUTUMN;
            else if (k==4 || k==5 || k==6)
                return Season.SUMMER;
            else 
                return Season.SPRING;               
        }
    }
    final class Person implements Comparable<Person>{

        private final String sName;
        Person(String n){sName = n;}
        public String name(){return sName;}
        public String toString(){return sName;}

        public boolean equals(Object ob){
            if (!(ob instanceof Person))
                return false;
            Person p = (Person)ob;
            return sName.equals(p.sName);
        }
        public int compareTo(Person p){
            return sName.compareTo(p.sName);
        }
        public int hashCode(){
            return sName.hashCode();
        }
    }

Answer 1

由于这是一项任务，我不会提供整个代码，但可以给你一个开始

    TreeSet<String> set = new TreeSet<>();
    set.add("Hello");
    set.add("World");
    set.add("!");

    // making an iterator for traversing each element in the set
    Iterator<String> iterator = set.iterator(); 
    // iterator will iterate till it has something to traverse
    while(iterator.hasNext()){
        System.out.println(iterator.next()); // printing the element
    }

    // creating a new String 
    String s = "hello";
    // printing the 2nd character of the String instance
    // Note : String is considered as 0 based index like array
    // so it will print 'l'
    System.out.println(s.charAt(2));

Answer 2

您可以尝试向Person类添加一个布尔字段（flag），指示sName是否以h开头（可以在构造函数中完成检查），还可以添加一个返回布尔变量值的getter方法。

因此在foreach循环中，您可以使用此getter方法来检查对象标志的状态。

如何搜索包含以字母H开头的名称的树集？如果是这样打印名称（JAVA）

2 个答案: