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Monday, February 3, 2014
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How to Perform Text Interaction with GUI in JAVA Programming

4:55 PMMonday, February 3, 2014
Java programming have a lot to learn and we have done some part with our earlier articles like variables, Data types. Now we are going to be designing of a GUI application involving these concepts. But wait, you need to know something more than this in order to design a GUI, application with full understanding. You need to know about to obtain/set the text from/into GUI components. Don’t worry; this section is here to serve this purpose.

For text interaction in GUI, you need to use basically four types of method:

getText()

A getText() method returns the text currently stored in a text based GUI components. The Swing components that support getText() method includes: Text Field, Text Area, Button, Label, Check Box and Radio Button.

Consider the example where you want to concatenate the contents of title, first name and last name fields, you must obtain the text in these fields. This you can do it with the help of getText() method.

To obtain text from title text field, you need to write:
titlezTF.getText()

The getText() returns a value of string type, so we must store the value returned by getText() in String type variable. Thus, complete statement to obtain text from title TF field would be
String str1 = titleTextField.getText();

Now you can manipulate the variable str1 (that now contains the text inside titleTF field) in the way you want.

Parse…()

Sometimes, you use text type components in a GUI but you intend to use it for obtaining numeric values e.g. you may want to read age of a person through a text fields. Since a text field return text i.e., string type of Data you need a method that helps you extract/convert this textual data into a numeric type. For this, parse…() methods are very useful. There are many parse…() methods that help you parse string into different numeric types.

These are
  • Byte.parseByte(String s) convert a sting s into a byte type value
  • Short.parseShort(String s) convert a String into a short type value
  • Integer.parseInt(String s) convert a String into an int type value
  • Long.parseLong(String s) convert a String into a long type value
  • Float.parseFloat(String s) convert a String into Float type value
  • Double.parseDouble(String s) converts a String into Double type value
To obtain a float value, you may use
Float.parseFloat(<text obtain from field>)
To obtain a double value, you my use
Double.parseDouble(<text obtained from field>)
To obtain a long value, you may use
Long.parseLong(<textobtained from field>)
And so on for other data types.
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