Java SE (Java Platform, Standard Edition)

I'm creating a java application (not a web application) and have a field call co2TxtBx. I can't seem to see my error, so perhaps some other eyes can find it.
When I try to convert the value typed into that textfield to an integer using these 2 below, I throw a NumberFormatException:

Integer c = Integer.valueOf(co2TxtBx.getText());
int CO2 = c.intValue();

or

int c = Integer.parseInt(co2TxtBx.getText());

BUT I don't throw an exception when I use this:

int c = (int)(Double.parseDouble(co2TxtBx.getText()));

Stack trace for Integer c = Integer.valueOf(co2TxtBx.getText());

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "22 "
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:456)
at java.lang.Integer.valueOf(Integer.java:553)
at medicalc.MediCalculator.calcPhBeBtnActionPerformed(MediCalculator.java:184)
at medicalc.MediCalculator.access$100(MediCalculator.java:13)
at medicalc.MediCalculator$2.actionPerformed(MediCalculator.java:91)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6041)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
at java.awt.Component.processEvent(Component.java:5806)
at java.awt.Container.processEvent(Container.java:2058)
at java.awt.Component.dispatchEventImpl(Component.java:4413)
at java.awt.Container.dispatchEventImpl(Container.java:2116)
at java.awt.Component.dispatchEvent(Component.java:4243)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
at java.awt.Container.dispatchEventImpl(Container.java:2102)
at java.awt.Window.dispatchEventImpl(Window.java:2440)
at java.awt.Component.dispatchEvent(Component.java:4243)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

Any thoughts on my misunderstanding of this? Thanks!