【刷题记录④】Java从0到1入门| 集合类_java set> entrys = map.e

import java.util.HashSet;
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();
        scanner.close();
        HashSet<Character> hs = new HashSet<>();
 
        //write your code here......
//          新建HashSet，然后遍历字符串，将所有字符添加到Set。 
//          由于HashSet本身结构不允许有重复的项，所以会自动去除重复的元素
        
        for(int i=0;i<str.length();i++){
            hs.add(str.charAt(i));
            //str.charAt (i)的意思是第i个字符在字符串str中所占的位置
            //不能直接使用str[i]这种方法来取字符串的值，这种取法只适合数组根据索引下标取值
        }
//         //第二种写法
//         //因为增强for循环只能够对数组进行循环，故我们应该先对str字符串进行toCharArray()将其数组化，进而取得其值
//         for(char c:str.toCharArray(){
//             hs.add(c);
//         }
        
        for (char c:hs) {
            System.out.print(c);
        }
    }
}

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        List<Integer> list = new ArrayList<>();
        int num1 = scanner.nextInt();
        int num2 = scanner.nextInt();
        int num3 = scanner.nextInt();
        int num4 = scanner.nextInt();
        int num5 = scanner.nextInt();
        scanner.close();
        list.add(num1);
        list.add(num2);
        list.add(num3);
        list.add(num4);
        list.add(num5);
        System.out.print("普通for循环:");
 
        //write your code here......
        for(int i=0;i<list.size();i++) System.out.print(list.get(i) + " ");
 
        System.out.println();
        System.out.print("增强for循环:");
 
        //write your code here......
        for(Integer x : list) System.out.print(x + " ");
 
        System.out.println();
        System.out.print("迭代器遍历:");
 
        //write your code here......
        Iterator iterator = list.iterator();
        while(iterator.hasNext()) System.out.print(iterator.next() + " ");
 
        System.out.println();
    }
}

import java.util.*;
 
public class Main {
    public static void main(String[] args) {
        Guest guest1 = new Guest("小明",false);
        Guest guest2 = new Guest("小军",false);
        Guest vipGuest = new Guest("小红",true);
        Deque<Guest> deque = new ArrayDeque<>();
        deque.add(guest1);
        deque.add(guest2);
        deque.addFirst(vipGuest);
        System.out.println(deque);
    }
}
class Guest{
    String name;
    Boolean vip;
 
    @Override
    public String toString() {
        return name;
    }
 
    public Guest(String name, Boolean vip) {
        this.name = name;
        this.vip = vip;
 
    }
}

import java.util.ArrayDeque;
import java.util.Scanner;
 
public class Main {
 
    public static void main(String[] args) {
        ArrayDeque deque = new ArrayDeque();
 
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String name = scanner.next();
            // 初始化队列中的数据
            deque.offerLast(name);
        }
 
        // write your code here......
        int l = deque.size();
        for (int i=0; i<l; i++) {
            if (i%2==0) {
                System.out.println(deque.pollFirst());
            }
            else {
                System.out.println(deque.pollLast());
            }
        }
 
    }
 
}

import java.util.*;
 
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String line = scanner.nextLine();
        Map<Character, Integer> map = new LinkedHashMap<Character, Integer>();
 line = line.replaceAll("[^a-zA-Z]", "");
for (int i = 0; i < line.length(); i++) {
    char c = line.charAt(i);
    if (map.containsKey(c)) {
        map.put(c, map.get(c) + 1);
    } else {
        map.put(c, 1);
    }
}
        //write your code here......
      
 
        Set<Map.Entry<Character, Integer>> entrys = map.entrySet();
        for (Map.Entry<Character, Integer> entry : entrys) {
            System.out.println(entry.getKey() + ":" + entry.getValue());
        }
    }
}

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;
 
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Customer customer1 = new Customer("小明",scanner.nextInt());
        Customer customer2 = new Customer("小军",scanner.nextInt());
        Customer customer3 = new Customer("小红",scanner.nextInt());
        List<Customer> customers = new ArrayList<>();
        customers.add(customer1);
        customers.add(customer2);
        customers.add(customer3);
 
        //调用排序接口
        Collections.sort(customers);
 
        System.out.println(customers);
 
    }
}
 
class Customer implements Comparable<Customer>{
    private String name;
    private int consumption;
 
    public Customer(String name, int consumption) {
        this.name = name;
        this.consumption = consumption;
    }
 
    @Override
    public String toString() {
        return "Customer{" +
                "name='" + name + '\'' +
                ", consumption=" + consumption +
                '}';
    }
 
    //重写compareTo()方法，按照消费额从高到低排序
    @Override
    public int compareTo(Customer c){
        return c.consumption-consumption;
    }
 
}