如何打破循环并打印数组的内容 [英] How to break out of a loop and print the contents of an array

问题描述

当用户输入完成"时，如何跳出循环?并打印用户输入的内容?另外，我希望能够在打印过程中找到数组的最小元素和数组的最大元素.

How can I break out of a loop when the user enters "done" and print the contents of what the user entered? Also, I would like to be able to find the smallest element of the array and the largest element of the array during the printing.

import java.util.Arrays;

public class array2 {
    public static void main(String[] args) {
        java.util.Scanner input = new java.util.Scanner(System.in);

        input.useDelimiter(System.getProperty("line.separator"));

        int numofpeople = 10;
        Person[] persons = new Person[numofpeople];

        for (int i = 0; i < numofpeople; i++) {
            System.out.print("Enter the person's name: ");
            String person = input.next();

            if(person.equals("done")){break;}

            System.out.print("Enter the persons's age: ");
            int age = (Integer) input.nextInt();
            persons[i] = new Person(person, age);
        }


    }

}

class Person implements Comparable<Person> {
    public String person;
    public Integer age;
    public Person(String s, Integer g) {
        this.person = s;
        this.age = g;
    }

    @Override
    public int compareTo(Person o) {
        return (this.age>o.age?1:-1);
    }
}

推荐答案

break 语句将使程序离开 for 循环.您没有代码可在 for 循环之外打印数组.实际上，循环之外没有任何代码.这将使您的程序退出，因为它位于 main 方法中.因此，您需要代码才能打印数组.

The break statement will make the program leave the for loop. You have no code to print the array outside of the for loop. In fact, there is no code outside of the loop. This will make your program exit since it is in the main method. So you need code to print the array.

完整的解决方案给出以下所有注释:

Complete Solution Given all comments below:

import java.util.ArrayList;

public class Array2 {

    public static void main(String[] args) {
        java.util.Scanner input = new java.util.Scanner(System.in);
        ArrayList<Person> persons = new ArrayList();
        int numOfPeople = 10;
        for (int i = 0; i < numOfPeople; i++) {
            System.out.print("Enter the person's name: ");
            String person = input.nextLine();
            if (person.trim().equalsIgnoreCase("done")) {
                break;
            }
            System.out.print("Enter the persons's age: ");
            int age = Integer.parseInt(input.nextLine());
            persons.add(new Person(person, age));
        }
        //Collections.sort(persons); //not sorting anymore
        for (Person person : persons) {
            System.out.println(person.name + ": " + person.age);
        }
        Person youngestPerson = getYoungest(persons);
        Person oldestPerson = getOldest(persons);
        System.out.println("Youngest: " + youngestPerson.name + ": " + youngestPerson.age);
        System.out.println("Oldest: " +oldestPerson.name + ": " + oldestPerson.age);

    }

    public static Person getYoungest(ArrayList<Person> people) {
        Person youngestPerson = null;
        for (Person person : people) {
            if (youngestPerson == null || person.age < youngestPerson.age) {
                youngestPerson = person;
            }
        }
        return youngestPerson;

    }

    public static Person getOldest(ArrayList<Person> people) {
        Person oldestPerson = null;
        for (Person person : people) {
            if (oldestPerson == null || person.age > oldestPerson.age) {
                oldestPerson = person;
            }
        }
        return oldestPerson;

    }

    protected static class Person implements Comparable<Person> {

        protected String name;
        protected int age;

        public Person(String name, int age) {
            this.name = name;
            this.age = age;
        }

        @Override
        public int compareTo(Person o) {
            return (this.age > o.age ? 1 : -1);
        }
    }

}

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