如何通过用户输入显示 JOptionPane

Question

我目前一直在努力弄清楚为什么我的数组值没有显示在对话框中。我正在做一个作业，其详细信息是：

"Write a program named TallestBuildingLookupthat contains an array of 10 TallestBuildingobjects and fill in it with the data given above accordingly. Then use dialog boxes to accept a building name and display the building’s location, height, and stories. If a match is not found, display an error message that includes the invalid name and allow the user to search for a new building name."

我的主要问题是让我的数组值从我的 toString() 方法显示，并在我没有收到数组中的名称时处理异常。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);
}

不要使用“==”来比较字符串，因为它比较的是一个引用，而不是它自身的值。检查 Java String.equals versus ==
使用 MessageDialog 向用户显示值，而不是 InputDialog
你应该在显示用户

for 循环

您应该保存在临时引用中找到的对象，以便之后显示它。

Answer 2

Specifically, getting the dialog box to loop to re-enter a name value and recheck the array.

好吧，您需要在某种类型的循环中请求输入，而您在代码中没有这样做。循环有两种主要形式——for 循环，当你事先知道你想循环多少次时使用（这里你不知道），——和 while loop 或者 do-while loop 当你事先不知道的时候。我建议您使用 do-while 循环，因为您希望至少从用户那里获得一次输入，这意味着循环必须至少运行一次，如果不是更多的话，然后一直循环直到输入有效。我会使用一个布尔值，比如说 boolean inputValid = false;。

其他问题：您的 for 循环已损坏。你在循环中对匹配与不匹配做出反应，这是不正确的，因为如果你这样做，你将给出为每个不匹配使用错误对话框，这不是您想要的。相反，您想检查循环内的匹配项，如果找到匹配项则设置一个布尔值，也许使用我上面提到的那个，然后在循环完成后，如果没有找到匹配项则显示错误消息，然后重复正如我提到的，do-while 循环。

My main issue is getting my array values to display from my toString() method, and handling the exception when I don't receive a name in the array.

如果您在这个问题上需要具体帮助，您将不得不告诉我们更多关于您显示的数据有什么问题。

如何通过用户输入显示 JOptionPane

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