java - 如何通过用户输入显示JOptionPane

Question

我目前一直在试图找出为什么我的数组值没有在对话框中显示。我正在做一项作业，其详细信息是:

“编写一个名为 TallestBuildingLookup 的程序，其中包含 10 个 TallestBuilding 对象的数组，并相应地填充上面给出的数据。然后使用对话框接受建筑物名称并显示建筑物的位置、高度和楼层。如果匹配，则为未找到，则显示一条包含无效名称的错误消息，并允许用户搜索新的建筑物名称。”

我的主要问题是从 toString() 方法获取要显示的数组值，并在数组中没有收到名称时处理异常。具体来说，让对话框循环以重新输入名称值并重新检查数组。任何帮助将不胜感激。

import javax.swing.*;

public class TallestBuildingLookup {

    static class TallestBuilding{
        private String name;
        private String city;
        private int height;
        private int stories;

        public TallestBuilding(String name, String city, int height, int stories)     {
            this.name = name;
            this.city = city;
            this.height = height;
            this.stories = stories; 
        }

        public String getName(){
            return this.name;
        }
        public String toString(){
            return  this.name + " of " + this.city + ", "+ this.stories + "stories/" + this.height + " feet high." ;    
        }
    }
    public static void main(String[] args){
        TallestBuilding[] tallestbuilding = new TallestBuilding[10];
        tallestbuilding[0] = new TallestBuilding("One World Trade Center", "New York", 1776, 104);
        tallestbuilding[1] = new TallestBuilding("Willis Tower", "Chicago", 1451, 108);
        tallestbuilding[2] = new TallestBuilding("Empire State", "New York", 1250, 102);
        tallestbuilding[3] = new TallestBuilding("Bank of America Tower", "New York", 1200, 55);
        tallestbuilding[4] = new TallestBuilding("Aon Center", "Chicago", 1136, 83 );
        tallestbuilding[5] = new TallestBuilding("John Hancock Center", "Chicago", 1127, 100);
        tallestbuilding[6] = new TallestBuilding("Wells Fargo Plaza", "Houston", 992,71 );
        tallestbuilding[7] = new TallestBuilding("Comcast Center", "Philidelphia", 974, 57 );
        tallestbuilding[8] = new TallestBuilding("Columbia Center", "Seattle", 967, 76);
        tallestbuilding[9] = new TallestBuilding("Key Tower", "Clevland", 947, 57);

        String entry = JOptionPane.showInputDialog("Enter a builing name");
        String name = (String) entry;

        System.out.println(name);

        for (int i=0; i<10; i++){
            if(name == tallestbuilding[i].getName() ){
                JOptionPane.showInputDialog(null, tallestbuilding[i] );
            }
            else{
                JOptionPane.showInputDialog("Sorry - no "+ name + " was found.");
            }
        }
    }
}

Answer 1

试试这个:

TallestBuilding tallestBuilding = null;
for (int i=0; i<10; i++){
    if(name.equals(tallestbuilding[i].getName())){
       tallestBuilding = tallestbuilding[i];
       break;
    }
}
if(tallestBuilding == null) {
    JOptionPane.showInputDialog("Sorry - no "+ name + " was found.");
} else {
    JOptionPane.showMessageDialog(null, tallestBuilding);
}

1. 不要使用“==”来比较字符串，因为它比较的是引用，而不是它本身的值。检查Java String.equals versus ==
2. 使用 MessageDialog 向用户显示值，而不是 InputDialog
3. 您应该在显示用户后中断for循环
4. 您应该保存在临时引用中找到的对象，以便稍后显示它。