New to Java

Hi I am new to Java and I am having problems with this code:

here is the error

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "3 "
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Integer.parseInt(Integer.java:492)
	at java.lang.Integer.parseInt(Integer.java:527)
	at NewJFrame.jButton_CalculateActionPerformed(NewJFrame.java:161)
	at NewJFrame.access$100(NewJFrame.java:10)
	at NewJFrame$2.actionPerformed(NewJFrame.java:61)

 
  private void jButton_CalculateActionPerformed(java.awt.event.ActionEvent evt) {                                                  
        // TODO add your handling code here:
          int numTables = Integer.parseInt(jTextField_NumberOfTables.getText());
        int numCalc = Integer.parseInt(jTextField_NumberOfCalculations.getText());
        String operator = jComboBox_Operation.getSelectedItem().toString();
        
        String table = ""; 
        
        if (operator.equalsIgnoreCase("powers")) {
               table = CalculateTables.powersTable(numTables, numCalc);
               jLabel_TableType.setText("powers");
        }

public class CalculateTables {
    
  public static String
           powersTable(int numTables, int numCalc) {
           
           //fill temArray with powers using nested for statements
           String output = "";
       for (int i =0; i <=  numTables; i++) {
          output += i + " Tables\r\n";      
                for (int j =0; j <= numCalc; j++) {
                    output += String.format("%s ^ %s = %.2f\r\n",i,j,Math.pow(i,j)); 
                }
    output += "\r\n";
}    
 return output;    
  }

It seems to me anyway that the Integer.parseInt(jTextField_NumberOfTables.getText());
is not working
this piece of code, I an getting text from the user and I need to onverted to an integer

 
 int numTables = Integer.parseInt(jTextField_NumberOfTables.getText());
        int numCalc = Integer.parseInt(jTextField_NumberOfCalculations.getText());