JSlide in Java Swing

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Sliders that are implemented in Swing through the JSlider class enables a number to be set by sliding a control within the range of a minimum and maximum values. In many cases, a slider can be used for numeric input instead of a text field, and it has the advantage of restricting input to a range of acceptable values.

A Slider is often seen in media players to adjust the audio volume, channel frequencies, contrast or brightness of picture, and so on.

Sliders are horizontaly by default. The orientation can be explicity set by using two class variables of the SwingConstants class: HORIZONTAL or VERICAL.

The following are the JSlider constructor methods:

JSlider(int, int)

Slider with the specified minimum value and maximum value.

JSlider(int, int, int)

Slider with the specified minimum value, maximum value, maximum value and starting value.

JSlider(int, int, int, int)

Slider with the specified orientation, minimum value, maximum value and staring value.

Slider component have an optional label that can be used to indicate the minimum value, maximum value and two different sets of tick marks rangining between the values.

The elements of this label are established by calling several methods of JSlider:

setMajorTickSpacing(int)

Separate major tick marks by the specified distance. The distance is not in pixels, but in value between the minimum and maximum values represented by the slider.

setMinorTickSpacing(int)

Separate minor tick mark by the specified distance. Minor ticks are half as tall as major ticks.

setPaintTicks(boolean)

Determine whether the tick marks should be displayed (a true argument) or not (a false argument).

setPaintLabels(boolean)

Determine whether the numeric label of the slider should be displayed (true) or not (false.).

These methods should be called on the slider before it is added to a container.

Example:

The following displays a slider that can control the speed at which a picture is animated.

/* =========================================================== File Name : JSliderDemo.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.border.*; import javax.swing.event.*; public class JSliderDemo extends JFrame implements ActionListener { //Set up animation parameters static final int FPS_INIT = 15; //initial frames per second int frameNumber=0; int delay; Timer timer; boolean frozen=false; Border border; //This label uses ImageIcon to show the doggy pictures. JLabel picture; JSliderDemo(String windowTitle) { super(windowTitle); delay = 1000 / FPS_INIT; //Create the slider and its label JLabel sliderLabel = new JLabel("Frames Per Second", JLabel.CENTER); JSlider framesPerSecond = new JSlider(JSlider.HORIZONTAL, 0, 30, FPS_INIT); framesPerSecond.addChangeListener(new SliderListener()); framesPerSecond.setMajorTickSpacing(10); // Specifies tick marks by a specified distance framesPerSecond.setMinorTickSpacing(1); // Specifies whether the tick marks should be displayed or not framesPerSecond.setPaintTicks(true); // Specifies whether the numeric label for the tick marks should be displayed or not framesPerSecond.setPaintLabels(true); //Create the label for the animation. The Image name start with T followed by a number picture = new JLabel(new ImageIcon("../images/T" + frameNumber + ".gif"), JLabel.CENTER); //Put everything in the content pane JPanel contentPane = new JPanel(); contentPane.setLayout(new BorderLayout()); contentPane.add(sliderLabel,BorderLayout.NORTH); contentPane.add(framesPerSecond,BorderLayout.CENTER); contentPane.add(picture,BorderLayout.SOUTH); setContentPane(contentPane); //Set up a timer that calls this object's action handler. timer = new Timer(delay, this); timer.addActionListener(this); timer.setInitialDelay(delay * 10); //pauses animation after frames //0 and 6 by restarting the timer timer.setCoalesce(true); //Add a listener for window events using adapter class addWindowListener(new WindowAdapter() { public void windowIconified(WindowEvent e) { stopAnimation(); } public void windowDeiconified(WindowEvent e) { startAnimation(); } public void windowClosing(WindowEvent e) { System.exit(0); } }); // End of Window Adapter } // End of SliderDemo constructor /** Listens to the slider. */ class SliderListener implements ChangeListener { public void stateChanged(ChangeEvent e) { JSlider source = (JSlider)e.getSource(); if (!source.getValueIsAdjusting()) // if the slider is not moved { int fps = (int)source.getValue(); //get the slider value if (fps == 0) { if (!frozen) stopAnimation(); } else { delay = 1000 / fps; timer.setDelay(delay); //set the delay time timer.setInitialDelay(delay * 10); if (frozen) startAnimation(); } } // End of if construct for getValueChanged() method } // End of stateChanged() method } // End of interface SliderListener public void startAnimation() { //Start (or restart) animating! timer.start(); frozen = false; } public void stopAnimation() { //Stop the animating thread. timer.stop(); frozen = true; } //Called when the Timer fires public void actionPerformed(ActionEvent e) { //Advance the animation frame. if (frameNumber==13) //frameNumber that keeps track of image files frameNumber = 0; else frameNumber++; // increment the image to be loaded picture.setIcon(new ImageIcon("../images/T" + frameNumber + ".gif")); if (frameNumber==0 || frameNumber==6) timer.restart(); } public static void main(String args[]) { JSliderDemo animator = new JSliderDemo("SliderDemo"); animator.pack(); animator.setVisible(true); animator.startAnimation(); } // End of main() method } // End of class declaration

C:\>jdk1.4\bin>javac JSliderDemo.java
C:\>jdk1.4\bin>java JSliderDemo

"Output of JSliderDemo.class"

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Java Swing-II

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