java - Java中有没有检测到没有输入的异常？

Question

如果我想检测用户是否输入了任何字符，我需要在 try catch block 中添加什么异常？

这是我的代码，我想知道用户是否没有输入任何内容，或者用户的输入是否已保存在地址簿中。我正在使用数组来存储我的条目:

public void addEntry() {
    entry[counter] = new AddressBookEntry();
    entry[counter].setName(JOptionPane.showInputDialog("Enter name: "));
    entry[counter].setAdd(JOptionPane.showInputDialog("Enter add: "));
    entry[counter].setPhoneNo(JOptionPane.showInputDialog("Enter Phone No.: "));
    entry[counter].setEmail(JOptionPane.showInputDialog("Enter E-mail: "));
    counter++;
}

我需要 try-catch 还是条件？这是我的完整代码:

public class AddressBook {

private AddressBookEntry entry[];
private int counter;
private String SName;
private int notfound = 0;

public static void main(String[] args) {
    AddressBook a = new AddressBook();
    a.entry = new AddressBookEntry[100];
    int option = 0;
    try {
        while (option != 5) {
            String content = "Choose an Option\n\n"
                    + "[1] Add an Entry\n"
                    + "[2] Delete an Entry\n"
                    + "[3] Update an Entry\n"
                    + "[4] View all Entries\n"
                    + "[5] View Specific Entry\n"
                    + "[6] Exit";
            option = Integer.parseInt(JOptionPane.showInputDialog(content));
            switch (option) {
                case 1:
                    a.addEntry();
                    break;
                case 2:
                    a.deleteEntry();
                    break;
                case 3:
                    a.editEntry();
                    break;
                case 4:
                    a.viewAll();
                    break;
                case 5:
                    a.searchEntry();
                    break;
                case 6:
                    System.exit(1);
                    break;
                default:
                    JOptionPane.showMessageDialog(null, "Invalid Choice!");
            }
        }
    }catch(NumberFormatException e){
        JOptionPane.showMessageDialog(null, "Please Choose a Number in the displayed Menu");
    }
}

public void addEntry() {
    entry[counter] = new AddressBookEntry();
    entry[counter].setName(JOptionPane.showInputDialog("Enter name: "));
    entry[counter].setAdd(JOptionPane.showInputDialog("Enter add: "));
    entry[counter].setPhoneNo(JOptionPane.showInputDialog("Enter Phone No.: "));
    entry[counter].setEmail(JOptionPane.showInputDialog("Enter E-mail: "));
    counter++;
}

public void viewAll() {
    String addText = "  NAME\tADDRESS\tPHONE NO.\tE-MAIL ADD\n\n";
    int nonNull = 0;
    for (int i = 0; i < entry.length; i++) {
        if (entry[i] != null) {
            addText = addText + entry[i].getInfo() + "\n";
            nonNull++;
        }
        if (nonNull == counter) {
            break;
        }
    }
    JOptionPane.showMessageDialog(null, new JTextArea(addText));
}

public void searchEntry() {
    SName = JOptionPane.showInputDialog("Enter Name to find: ");
    searchMethod();
}

public void searchMethod() {
    for (int i = 0; i < counter; i++) {
        if (entry[i].getName().equals(SName)) {
            JOptionPane.showMessageDialog(null, entry[i].getInfo2());
            notfound = 0;
            break;
        } else {
            notfound++;
        }
    }
    if (notfound != 0) {
        JOptionPane.showMessageDialog(null, "Name Not Found!");
    }
}

public void editEntry() {
    SName = JOptionPane.showInputDialog("Enter Name to edit: ");
    for (int i = 0; i < counter; i++) {
        if (entry[i].getName().equals(SName)) {
            entry[i] = new AddressBookEntry();
            entry[i].setName(JOptionPane.showInputDialog("Enter new name: "));
            entry[i].setAdd(JOptionPane.showInputDialog("Enter new add: "));
            entry[i].setPhoneNo(JOptionPane.showInputDialog("Enter new Phone No.: "));
            entry[i].setEmail(JOptionPane.showInputDialog("Enter new E-mail: "));
            notfound = 0;
            break;
        } else {
            notfound++;
        }
    }
    if (notfound != 0) {
        JOptionPane.showMessageDialog(null, "Name Not Found!");
    }
}

public void deleteEntry() {
    SName = JOptionPane.showInputDialog("Enter Name to delete: ");
    for (int i = 0; i < counter; i++) {
        if (entry[i].getName().equals(SName)) {
            JOptionPane.showMessageDialog(null, "Found!");
            entry[i] = null;
            break;
        }
    }
}

}

我的 addEntry() 方法有问题，因为我想检测用户新添加的条目是否已存储在我的地址簿中，以及当我询问时用户是否未输入任何内容在 JOptionPane 中“输入名称:”，然后仍然按“确定”。

Answer 1

虽然不太清楚你的问题，但我会尽力回答。
在这种情况下，您可以在此处手动创建自己的异常，例如，

throw new MyException();    

由于您的条件“用户没有输入任何字符”本身并不清晰，我建议您可以尝试通过检查参数的数量来抛出异常通过命令行传递。
如果它是 0，即没有传递任何参数，您可以抛出自己的异常。

但就其本身而言，不会引发异常。