Chapter: Java The Complete Reference - The Java Library - Using AWT Controls, Layout Managers, and Menus

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Labels - AWT Controls

The easiest control to use is a label. A label is an object of type Label, and it contains a string, which it displays. Labels are passive controls that do not support any interaction with the user.

Labels

 

The easiest control to use is a label. A label is an object of type Label, and it contains a string, which it displays. Labels are passive controls that do not support any interaction with the user. Label defines the following constructors:

 

Label( ) throws HeadlessException Label(String str) throws HeadlessException

Label(String str, int how) throws HeadlessException

 

The first version creates a blank label. The second version creates a label that contains the string specified by str. This string is left-justified. The third version creates a label that contains the string specified by str using the alignment specified by how. The value of how must be one of these three constants: Label.LEFT, Label.RIGHT, or Label.CENTER.

 

You can set or change the text in a label by using the setText( ) method. You can obtain the current label by calling getText( ). These methods are shown here:

 

void setText(String str) String getText( )

 

For setText( ), str specifies the new label. For getText( ), the current label is returned. You can set the alignment of the string within the label by calling setAlignment( ). To

obtain the current alignment, call getAlignment( ). The methods are as follows:

 

void setAlignment(int how) int getAlignment( )

 

Here, how must be one of the alignment constants shown earlier.

 

The following example creates three labels and adds them to an applet window:

 

// Demonstrate Labels

import java.awt.*; import java.applet.*; /*

 

<applet code="LabelDemo" width=300 height=200> </applet>

 

*/

 

public class LabelDemo extends Applet { public void init() {

 

Label one = new Label("One"); Label two = new Label("Two"); Label three = new Label("Three");

 

// add labels to applet window

add(one);

 

add(two);

 

add(three);

 

}

 

}

 

Here is sample output from the LabelDemo applet. Notice that the labels are organized in the window by the default layout manager. Later, you will see how to control more precisely the placement of the labels.




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