Solved

scrollpane and scrollbar

Posted on 2001-06-14
6
255 Views
Last Modified: 2010-03-31
i wonder how to control a scrollbar together with a scrollpane? can any one provide me a simple example on this.

what if i want the scrollbar to always scroll down to the last page/end of file, what should i do? can any provide me the example/source on this?
0
Comment
Question by:cys050200
  • 3
  • 2
6 Comments
 
LVL 1

Expert Comment

by:saurav17
ID: 6193962


hi,
pls., be clear on what u r saying.
I dont get ur concept., Could u give me more details abt., what u want.


regards,
K.J.S.
0
 
LVL 9

Expert Comment

by:Ovi
ID: 6193963
simply set all the time the caret from your text object used for displaying to point to the end of the document, call an scroll.updateUI(); and that's all.
0
 
LVL 1

Expert Comment

by:saurav17
ID: 6193976


hi,
pls., be clear on what u r saying.
I dont get ur concept., Could u give me more details abt., what u want.


regards,
K.J.S.
0
Live: Real-Time Solutions, Start Here

Receive instant 1:1 support from technology experts, using our real-time conversation and whiteboard interface. Your first 5 minutes are always free.

 

Author Comment

by:cys050200
ID: 6194209
for example, here are some codes for a class which extends JFrame:

 JTextArea outputArea = new JTextArea(30,60);
 JScrollPane scroller = new JScrollPane(outputArea);
 String str = "xxxx" ; //the str may be very long

 scroller.setAutoscrolls(true);
 outputArea.setAutoscrolls(true);
 outputArea.setText(str);
 
 Container c = getContentPane();
 c.setLayout(new BorderLayout());
 c.add(scroller,BorderLayout.CENTER);

 my question is, in the above situation, why is that my output(the scroller) is not scrolled down automatically if the str input is very long(longer than a page, for example).
0
 
LVL 9

Accepted Solution

by:
Ovi earned 100 total points
ID: 6194409
Do'it like this :

JTextArea outputArea = new JTextArea(30,60);
JScrollPane scroller = new JScrollPane(outputArea);
String str = "xxxx" ; //the str may be very long

scroller.setAutoscrolls(true);
outputArea.setAutoscrolls(true);
outputArea.setText(str);
updateScroll();

Container c = getContentPane();
c.setLayout(new BorderLayout());
c.add(scroller,BorderLayout.CENTER);
.....

private void updateScroll() {
outputArea.setCaretPosition(outputArea.getText().length() - 1);
}

Every time you update the text or append some text to your JTextArea call updateScroll() method.
0
 
LVL 9

Expert Comment

by:Ovi
ID: 6194418
you may need an try/catch in the method updateScroll for invalid location like this :

private void updateScroll() {
  try {
    outputArea.setCaretPosition(outputArea.getText().length() - 1);
  catch(Exception e) {
    System.out.println(e.toString());
  }
}

What is done at setCaretLocation ? The caret position is updated after that is build an Rectangle object based on the new location and called the scrollPane method scrollRectToVisible(Rectangle r)
0

Featured Post

Courses: Start Training Online With Pros, Today

Brush up on the basics or master the advanced techniques required to earn essential industry certifications, with Courses. Enroll in a course and start learning today. Training topics range from Android App Dev to the Xen Virtualization Platform.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
maven project error 5 54
login jsp example 24 46
Java: How do I open the default windows program for a given file type 3 28
String array comparison 4 32
Introduction Java can be integrated with native programs using an interface called JNI(Java Native Interface). Native programs are programs which can directly run on the processor. JNI is simply a naming and calling convention so that the JVM (Java…
Java functions are among the best things for programmers to work with as Java sites can be very easy to read and prepare. Java especially simplifies many processes in the coding industry as it helps integrate many forms of technology and different d…
Viewers learn about the “while” loop and how to utilize it correctly in Java. Additionally, viewers begin exploring how to include conditional statements within a while loop and avoid an endless loop. Define While Loop: Basic Example: Explanatio…
Viewers will learn how to properly install Eclipse with the necessary JDK, and will take a look at an introductory Java program. Download Eclipse installation zip file: Extract files from zip file: Download and install JDK 8: Open Eclipse and …

786 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question