UPDATE of How to get string from JTextField and save it in variable?

Question

I recently run in to same problem as this guy 4 years before. He get some answers there but non of it work either for him or me and then the question was not updated anymore. How to get string from JTextField and save it in variable?

The point is to check what is typed in textfield and if, like in example is yet decimal dot in the TextField, then consume event and not allow to add second decimal dot.

Main problem I figured out is that I need to add this inside the key event as shown belox. But this. statement inside the event reffers to event itself and not on JTextField.So I need to find bypass or other solution how to write getText statement

String text = this.getText().toString();

if someone have ideas of how to improve code as well I'm opened to any suggestions except for rewriting it as formatted field because the user experience is a little different, from the point where I was trying formatted field.

public class TxtfNumber extends JTextField {

 String text = this.getText().toString();  

 public TxtfNumber(){

KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(new KeyEventDispatcher() {

            @Override
            public boolean dispatchKeyEvent(KeyEvent evt) {
                switch (evt.getID()) {
                    case KeyEvent.KEY_TYPED:
                            String text = this.getText().toString();
                            if(evt.getKeyChar()=='.'&& text.contains(".")){
                               evt.consume();
                                } 
                           
                            
                    }

                    return false;
            }
        });
}
} 

Answer 1

SOLUTION

I accidentally run in solution when I used lambda expression. The formula you need to use is the name of class then .this. So in this case,

String text = TxtfNumber.this.getText().toString();

is the solution.

But eventually, when I know how to implement JTextField, I no longer need a solution by string. So I'm giving the whole code here for later use. Feel free to use it as Choose Bean component.

It restricts the user to use only one minus sign at the start of the text, one decimal dot anywhere and then type in two decimal numbers.

import java.awt.KeyEventDispatcher;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;
import javax.swing.JTextField;


public class TxtfNumber extends JTextField {



    public TxtfNumber(){

 KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(new KeyEventDispatcher() {
     @Override
     public boolean dispatchKeyEvent(KeyEvent evt) {
         switch (evt.getID()) {
             case KeyEvent.KEY_TYPED:
                 //restricts input charactes
                 if(!Character.isDigit(evt.getKeyChar()) && (evt.getKeyChar()!='.') && (evt.getKeyChar()!='-') && (evt.getKeyChar()!=','))
                     evt.consume();
                 
                 //change , and . for securing of different keyboard language
                 if (evt.getKeyChar()==',')
                     evt.setKeyChar('.');
                 
                 //allow only one decimal dot in text
                 if (evt.getKeyChar()=='.' && TxtfNumber.this.getText().contains(".")) 
                     evt.consume();
                 
                 //allow minus sign only at the start of text
                 if (evt.getKeyChar()=='-' && TxtfNumber.this.getText().length() != 0)
                     evt.consume();
                 
                 //allow two decimal numbers after dot
                 for (int i = -1; (i = TxtfNumber.this.getText().indexOf(".", i + 1)) != -1; i++) {
                     if (i+3 == TxtfNumber.this.getText().length()) 
                         evt.consume();
                 }
                 break;
         }
         return false;
     }
 });

    }
};