等待TextField输入，然后继续执行代码

Question

I have a Graphical User Interface that has a TextField , my code looks as following:

int port = 0;
    try{
    port = Integer.parseInt(frame.textfieldInput.getText());
    }
    catch(NumberFormatException npe)
    {
        System.out.println("Error! parse exception");
    }

    System.out.println("The Port is " + port); //is 0

I have to assign the value '0' to port, because otherwise the code wont compile, because the variable wouldn't be initialized.

Because the TextField is empty at the beginning of the Program, getText() wont get a value, which is why port stays '0'.

Is there any way to wait for the input before the code continues?

Answer 1

Found a solution, this is how I solved it:

I created a global variable outside of my ActionListener :

public String value = "";
public void createInput() {
    buttonInput.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            value = textfieldInput.getText();

        }

    });
}

named 'value'.

in my public static void main(String[] args) I declared the following:

while(frame.value.equalsIgnoreCase(""))
{
    try
    {
        System.out.println("waiting...");
        Thread.sleep(1000);
    }
    catch(InterruptedException ie)
    {
    System.out.println("interrupted");
    }
}

I just have to clear the variable 'value' everytime I used it, so it is empty again for future uses.

I tis not the best way to solve it, but it worked for me.

Answer 2

Below code may give you some idea to more efficient way to get value on focus lost.

JFrame frame = new JFrame();
frame.setSize(50, 50);
TextField field = new TextField();
field.addFocusListener(new FocusListener() {

    @Override
    public void focusLost(FocusEvent e) {
        // continue from here
        System.out.println(field.getText());
    }

    @Override
    public void focusGained(FocusEvent e) {
        // TODO Auto-generated method stub

    }
});
frame.getContentPane().add(field);
frame.setVisible(true);