动态JTextArea，等待用户输入，如Netbeans Console

Question

I am creating an IDE in swing where user can compile and run their java program. Here, output of the user's program will be shown to a JEditorPane . i am using reflection to do so.

I have set the input stream to a JTextArea by using System.setIn() and output stream to JEdotorPane by using System.setOut() method.

Now, the Problem is that when user run a program which have console input like System.in.read(); it do't wait for user input, from JEditorPane . It just run the program and read whole data from JTextArea . and further process other line of code.

Now, i want that the program output should wait for the user input and when user provide input in JTextArea and hit enter, then further processing of inputted text is done.

Another Way: via CMD

Actually, its little bit complicated to make an JTextPane as dynamic windows... and i have to do some more research on this particular topic...

So for now, i just did some changes in the way of showing Output. i am creating a separate Process by using Runtime class and execute that process in Command Prompt(CMD).

So, when the program generates an output. it shown on the command prompt... like many IDEs supports this mechanism... for example... Code Block.

for now, Its working fine...

Answer 1

I'd recommend using a DocumentFilter to listen for updates to the JTextArea .

From there you can veto changes, or insert them only at the end of the document. Also, it'll notify you when updates are made to the document so you can send them to your program. This should simplify your life.

I would strongly advise against using a KeyListener - they're very finicky with things like focus.

Here's an example of adding a DocumentFilter

    final Document d = textArea.getDocument();
    if(d instanceof AbstractDocument){
        ((AbstractDocument)d).setDocumentFilter(new DocumentFilter(){               
            @Override
            public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException{
                //Only allow edits at end (yours will be more complicated)
                System.out.println("Called replace");
                if(offset == d.getLength()){
                    //Edit only goes through if the filter bypass is used
                    fb.replace(offset, length, text, attrs);
                }
            }
        });
    }

Answer 2

Hey why don't you check the source of the NetBeans Output window for "inspiration": OutputTab.java

look here also: output2 src dir

Answer 3

hmm, you can probably process the enter key using a KeyListener (If you don't know, you should implement it in the gui (or component) class, and than add it to the component.) and than continue the processing of the rest of the program's input. I would think this:

    @Override
    public void KeyPressed(KeyEvent e){
    if(e.getKey == e.VK_ENTER){
    processText();
    keepProcessing();

    }

I hope this helps! good luck.