从 JTextArea 将文本存储为 arraylist

Question

I need to create a program to store all words in an array list. Then check the user input from the textfield to see if it starts with anything other than numbers and punctuation. Otherwise it will need to display an error and prvent the string to be added to the arraylist and display an appropriate error.

https://pastebin.com/8UwDm4nE

Heres the ActionEvent listener that contins the code to check that. Im not really sure how to get it working.

@Override
public void actionPerformed(ActionEvent e) {
    for(int i = 0; i < 1; i++) {
        String str = tf.getText(); // MUST BE STORED ON AN ARRAY LIST
        ta.append(str + "\n"); // Append the text on new line each

        if(str.startsWith(String.valueOf(nums))) { // Check input for a number at the start
            error.setText("Error: Word starts a number. Please try again!");
            error.setForeground(Color.RED);
            ta.append("");
        } else if (str.startsWith(String.valueOf(punct))) { // Check if input contains a punctuation at the start
            error.setText("Error: Word starts with an illegal character. Please try again!");
            error.setForeground(Color.RED);
            ta.append("");
        }
    }
}

Answer 1

I'm going to rephrase your problem a bit as clarification, please correct me if I'm misunderstanding.

You have a text field and a text area. You want a user to type a word into the text field and submit it. If that word starts with a number or punctuation, then indicate an error to the user. Otherwise, add it to the text area (on a new line) and the inner ArrayList.

To solve this problem, there are a couple things you'll need:

1. An ArrayList<String> that is a class member variable where you can store your words
2. An event handler that handles the button click.

The event handler should:

1. Parse the string from the text field (using getText() , as you already are).
2. Do the error checks you're already doing.
3. If neither of the error conditions are hit (so add an else clause for this), add the word to the text area (which you're already doing) and add it to the ArrayList.

Hopefully this helps you get a clearer idea of how to approach the problem. If not, please post a code sample of what you tried and what error you're specifically running into.

EDIT: Here is some pseudocode for your if-else error-handling block of code, assuming you declare a new ArrayList to hold your words as a class member:

// as class member variable
List<String> wordList = new ArrayList<>();

// word handler code
if (str starts with a number) {
    // handle error
} else if (str starts with punctuation) {
    // handle error
} else {
    ta.append(str + "\n");
    wordList.add(str);
}