使用switch和try语句验证用户输入... [英] Using switch and try statements to validate user input...

问题描述

一旦我尝试编译我的程序，我收到以下错误：

Once I try to compile my program I receive the following errors:

C:\Java 1\New folder (2)\Chapter 04\MyType.java:53: 'catch' without 'try'
				catch(NumberFormatException e)
                                
C:\Java 1\New folder (2)\Chapter 04\MyType.java:23: 'try' without 'catch' or 'finally'
			try

我的尝试：

What I have tried:

import java.io.*;
import javax.swing.JOptionPane;

public class MyType
{
	public static void main(String[] args)
	{
		String strChoice = "", strTryString, strTryInt, strTryDouble;
		int choice, tryInt;
		double tryDouble;
		boolean done = false;

		while(!done)
		{
			try // 1st error
			{
				System.out.println("What's my type?");
				strChoice = JOptionPane.showInputDialog(null,"\n\n\n1) String\n2) integer\n3) double\n4) Quit the program");
				choice = Integer.parseInt(strChoice);
				switch(choice)
			    {
					case 1:
					     JOptionPane.showMessageDialog(null, "Correct, any input can be saved as a String");
					     break;

					case 2:
					     JOptionPane.showMessageDialog(null, "Correct!");
					     tryInt = Integer.parseInt(strChoice);
					     break;

					case 3:
					     JOptionPane.showMessageDialog(null, "Correct!");
					     tryDouble = Integer.parseInt(strChoice);
					     break;

					case 4:
					     done = true;
					     JOptionPane.showMessageDialog(null, "Exit.");
					     System.exit(0);
					     break;

					default:
						 throw new NumberFormatException();
				}
				catch(NumberFormatException e) // 2nd error
				{
					JOptionPane.showMessageDialog(null, "Invalid, try again.");
				}

			}
		}
	}
}

//所有大括号都正确对齐。

// All of the braces are correctly aligned.

推荐答案

你的catch块在你的try块里面; s / b

Your "catch" block is "inside" your "try" block; s/b

try {
...
} catch (...) {
...
}

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