Question

我一直在寻找答案，但似乎可以找到答案。如何仅打印此Arraylist中tailLength等于或高于用户指定值的对象？如果竞赛等于tax，则tailLength应自动设置为3.7。我有一个问题，想弄清楚如何做到这一点。正如您所看到的，我有一种方法可以检查竞争是否为tax，如果没有，则计算尾部的长度。

所以我的问题基本上是，如何让这项工作成功？我想在我的方法中检查竞争是否为tax，并且我还想打印出arraylist中具有与用户指定值相等或更高的值的对象。到目前为止，这是我的两个班级：

PS。我知道我必须添加一些东西才能完成这项工作，但我一直在寻找几个小时而无法找到答案。

import java.util.ArrayList;
import java.util.Scanner;

public class MainProgram 
{

public static void main(String[] args) 
{
    ArrayList<Dog> doglist = new ArrayList<Dog>();
    Scanner myscan = new Scanner(System.in);
    boolean running = true;
    while(running)
        {
        System.out.println("\n************************************");
        System.out.println("\nVälkommen till Kennelklubben!");
        System.out.println("\n************************************");
        System.out.println("\n[1] Register new dog");
        System.out.println("[2] Print out list");
        System.out.println("[3] Increase age");
        System.out.println("[4] Remove dog");
        System.out.println("[5] Quit program");
        System.out.println("\n************************************");
        System.out.println("\nChoose: ");

        int option = myscan.nextInt();

        switch (option)
        {
            case 1:
                System.out.println("Write name:");
                String name = myscan.next();
                System.out.println("Write race:");
                String race = myscan.next();
                System.out.println("Age:");
                int age = myscan.nextInt();
                System.out.println("Weight:");
                double weight = myscan.nextDouble();


                doglist.add(new Dog(name, race, age, weight));

                break;




            case 2:

                System.out.println("Write minimum length of tail:");
                double tail = myscan.nextDouble();

                for (Dog name1 : doglist) 
                {
                    System.out.println(name1.toString());

                }




                break;



public class Dog 
{
    private String name;
    private String race;
    private int age;
    private double weight;
    private double tailLength;

public Dog (String name, String race, int age, double weight)
{
    this.name = name;
    this.race = race;
    this.age = age;
    this.weight = weight;

}


public double tailLength()
{
    if (race=="tax")
        tailLength = 3.7;
    else
        tailLength=(age-weight)/10;

    return tailLength;
}

public String toString()
{
    return name + " " + race +
            " " + age + " " + "år" + " " + weight + " " + "kg" + " " + tailLength;
}

}

Answer 1

我认为您应该更改Dog类的位构造函数。我建议在构造函数中初始化tailLength变量：

public Dog (String name, String race, int age, double weight) {
    this.name = name;
    this.race = race;
    this.age = age;
    this.weight = weight;
    if(race.equals("tax")) {
        this.taillength = 3.7; 
    } else {
        this.tailLength = (age - weight) / 10;
    }

}

就我没有误解你的问题而言，我认为在你的case 2中你应该遍历Dog的每个dogList个实例。使用＆＃34; if＆＃34;声明您检查存储在dog tailLength变量中的值，如果它高于tail（用户输入的值），则将该狗打印到控制台：

case 2:
System.out.println("Write minimum length of tail:");
double tail = myscan.nextDouble();
for(Dog d : doglist) {
    if(d.tailLenght >= tail) {
        System.out.println(d); /* You don't need to use d.toString() to print to the console,
        when you use variable's name in the method printing out to the console, it 
        automatically uses its toString() method. */
    }
}
break;

只有满足特定条件时才打印出arraylist的对象，如果满足条件，则将变量设置为特定值？

1 个答案: