https://openjdk.java.net/ 
/*
 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package javax.swing;

import java.awt.Component;


 An instance of the Spring class holds three properties that
 characterize its behavior: the minimum, preferred, and
 maximum values. Each of these properties may be involved in
 defining its fourth, value, property based on a series of rules.
 

 An instance of the Spring class can be visualized as a
 mechanical spring that provides a corrective force as the spring is compressed
 or stretched away from its preferred value. This force is modelled
 as linear function of the distance from the preferred value, but with
 two different constants -- one for the compressional force and one for the
 tensional one. Those constants are specified by the minimum and maximum
 values of the spring such that a spring at its minimum value produces an
 equal and opposite force to that which is created when it is at its
 maximum value. The difference between the preferred and
 minimum values, therefore, represents the ease with which the
 spring can be compressed and the difference between its maximum
 and preferred values, indicates the ease with which the
 Spring can be extended. See the sum method for details. 

 By defining simple arithmetic operations on Springs,
 the behavior of a collection of Springs
 can be reduced to that of an ordinary (non-compound) Spring. We define
 the "+", "-", max, and min operators on
 Springs so that, in each case, the result is a Spring
 whose characteristics bear a useful mathematical relationship to its constituent
 springs.
 

 A Spring can be treated as a pair of intervals
 with a single common point: the preferred value.
 The following rules define some of the
 arithmetic operators that can be applied to intervals
 ([a, b] refers to the interval
 from a
 to b,
 where a <= b).
 
         [a1, b1] + [a2, b2] = [a1 + a2, b1 + b2]
                     -[a, b] = [-b, -a]
     max([a1, b1], [a2, b2]) = [max(a1, a2), max(b1, b2)]
 

 

 If we denote Springs as [a, b, c],
 where a <= b <= c, we can define the same
 arithmetic operators on Springs:
 
         [a1, b1, c1] + [a2, b2, c2] = [a1 + a2, b1 + b2, c1 + c2]
                          -[a, b, c] = [-c, -b, -a]
     max([a1, b1, c1], [a2, b2, c2]) = [max(a1, a2), max(b1, b2), max(c1, c2)]
 

 

 With both intervals and Springs we can define "-" and min
 in terms of negation:
 
     X - Y = X + (-Y)
     min(X, Y) = -max(-X, -Y)
 

 

 For the static methods in this class that embody the arithmetic
 operators, we do not actually perform the operation in question as
 that would snapshot the values of the properties of the method's arguments
 at the time the static method is called. Instead, the static methods
 create a new Spring instance containing references to
 the method's arguments so that the characteristics of the new spring track the
 potentially changing characteristics of the springs from which it
 was made. This is a little like the idea of a lazy value
 in a functional language.


If you are implementing a SpringLayout you
can find further information and examples in
How to Use SpringLayout,
a section in The Java Tutorial.


Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing.  As of 1.4, support for long term storage
of all JavaBeans™
has been added to the java.beans package. Please see XMLEncoder. 
Author:     Philip Milne
See Also:
Since:      1.4
/**
 *  An instance of the <code>Spring</code> class holds three properties that
 *  characterize its behavior: the <em>minimum</em>, <em>preferred</em>, and
 *  <em>maximum</em> values. Each of these properties may be involved in
 *  defining its fourth, <em>value</em>, property based on a series of rules.
 *  <p>
 *  An instance of the <code>Spring</code> class can be visualized as a
 *  mechanical spring that provides a corrective force as the spring is compressed
 *  or stretched away from its preferred value. This force is modelled
 *  as linear function of the distance from the preferred value, but with
 *  two different constants -- one for the compressional force and one for the
 *  tensional one. Those constants are specified by the minimum and maximum
 *  values of the spring such that a spring at its minimum value produces an
 *  equal and opposite force to that which is created when it is at its
 *  maximum value. The difference between the <em>preferred</em> and
 *  <em>minimum</em> values, therefore, represents the ease with which the
 *  spring can be compressed and the difference between its <em>maximum</em>
 *  and <em>preferred</em> values, indicates the ease with which the
 *  <code>Spring</code> can be extended.
 *  See the {@link #sum} method for details.
 *
 *  <p>
 *  By defining simple arithmetic operations on <code>Spring</code>s,
 *  the behavior of a collection of <code>Spring</code>s
 *  can be reduced to that of an ordinary (non-compound) <code>Spring</code>. We define
 *  the "+", "-", <em>max</em>, and <em>min</em> operators on
 *  <code>Spring</code>s so that, in each case, the result is a <code>Spring</code>
 *  whose characteristics bear a useful mathematical relationship to its constituent
 *  springs.
 *
 *  <p>
 *  A <code>Spring</code> can be treated as a pair of intervals
 *  with a single common point: the preferred value.
 *  The following rules define some of the
 *  arithmetic operators that can be applied to intervals
 *  (<code>[a, b]</code> refers to the interval
 *  from <code>a</code>
 *  to <code>b</code>,
 *  where <code>a &lt;= b</code>).
 *
 *  <pre>
 *          [a1, b1] + [a2, b2] = [a1 + a2, b1 + b2]
 *
 *                      -[a, b] = [-b, -a]
 *
 *      max([a1, b1], [a2, b2]) = [max(a1, a2), max(b1, b2)]
 *  </pre>
 *  <p>
 *
 *  If we denote <code>Spring</code>s as <code>[a, b, c]</code>,
 *  where <code>a &lt;= b &lt;= c</code>, we can define the same
 *  arithmetic operators on <code>Spring</code>s:
 *
 *  <pre>
 *          [a1, b1, c1] + [a2, b2, c2] = [a1 + a2, b1 + b2, c1 + c2]
 *
 *                           -[a, b, c] = [-c, -b, -a]
 *
 *      max([a1, b1, c1], [a2, b2, c2]) = [max(a1, a2), max(b1, b2), max(c1, c2)]
 *  </pre>
 *  <p>
 *  With both intervals and <code>Spring</code>s we can define "-" and <em>min</em>
 *  in terms of negation:
 *
 *  <pre>
 *      X - Y = X + (-Y)
 *
 *      min(X, Y) = -max(-X, -Y)
 *  </pre>
 *  <p>
 *  For the static methods in this class that embody the arithmetic
 *  operators, we do not actually perform the operation in question as
 *  that would snapshot the values of the properties of the method's arguments
 *  at the time the static method is called. Instead, the static methods
 *  create a new <code>Spring</code> instance containing references to
 *  the method's arguments so that the characteristics of the new spring track the
 *  potentially changing characteristics of the springs from which it
 *  was made. This is a little like the idea of a <em>lazy value</em>
 *  in a functional language.
 * <p>
 * If you are implementing a <code>SpringLayout</code> you
 * can find further information and examples in
 * <a
 href="https://docs.oracle.com/javase/tutorial/uiswing/layout/spring.html">How to Use SpringLayout</a>,
 * a section in <em>The Java Tutorial.</em>
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @see SpringLayout
 * @see SpringLayout.Constraints
 *
 * @author      Philip Milne
 * @since       1.4
 */
public abstract class Spring {

    
An integer value signifying that a property value has not yet been calculated.

/**
     * An integer value signifying that a property value has not yet been calculated.
     */
    public static final int UNSET = Integer.MIN_VALUE;

    
Used by factory methods to create a Spring.

See Also:
/**
     * Used by factory methods to create a <code>Spring</code>.
     *
     * @see #constant(int)
     * @see #constant(int, int, int)
     * @see #max
     * @see #minus
     * @see #sum
     * @see SpringLayout.Constraints
     */
    protected Spring() {}

    
Returns the minimum value of this Spring.

Returns:the minimumValue property of this Spring
/**
     * Returns the <em>minimum</em> value of this <code>Spring</code>.
     *
     * @return the <code>minimumValue</code> property of this <code>Spring</code>
     */
    public abstract int getMinimumValue();

    
Returns the preferred value of this Spring.

Returns:the preferredValue of this Spring
/**
     * Returns the <em>preferred</em> value of this <code>Spring</code>.
     *
     * @return the <code>preferredValue</code> of this <code>Spring</code>
     */
    public abstract int getPreferredValue();

    
Returns the maximum value of this Spring.

Returns:the maximumValue property of this Spring
/**
     * Returns the <em>maximum</em> value of this <code>Spring</code>.
     *
     * @return the <code>maximumValue</code> property of this <code>Spring</code>
     */
    public abstract int getMaximumValue();

    
Returns the current value of this Spring.

See Also:
Returns: the value property of this Spring
/**
     * Returns the current <em>value</em> of this <code>Spring</code>.
     *
     * @return  the <code>value</code> property of this <code>Spring</code>
     *
     * @see #setValue
     */
    public abstract int getValue();

    
Sets the current value of this Spring to value.

Params:
  • value – the new setting of the value property
See Also:
/**
     * Sets the current <em>value</em> of this <code>Spring</code> to <code>value</code>.
     *
     * @param   value the new setting of the <code>value</code> property
     *
     * @see #getValue
     */
    public abstract void setValue(int value);

    private double range(boolean contract) {
        return contract ? (getPreferredValue() - getMinimumValue()) :
                          (getMaximumValue() - getPreferredValue());
    }

    /*pp*/ double getStrain() {
        double delta = (getValue() - getPreferredValue());
        return delta/range(getValue() < getPreferredValue());
    }

    /*pp*/ void setStrain(double strain) {
        setValue(getPreferredValue() + (int)(strain * range(strain < 0)));
    }

    /*pp*/ boolean isCyclic(SpringLayout l) {
        return false;
    }

    /*pp*/ static abstract class AbstractSpring extends Spring {
        protected int size = UNSET;

        public int getValue() {
            return size != UNSET ? size : getPreferredValue();
        }

        public final void setValue(int size) {
            if (this.size == size) {
                return;
            }
            if (size == UNSET) {
                clear();
            } else {
                setNonClearValue(size);
            }
        }

        protected void clear() {
            size = UNSET;
        }

        protected void setNonClearValue(int size) {
            this.size = size;
        }
    }

    private static class StaticSpring extends AbstractSpring {
        protected int min;
        protected int pref;
        protected int max;

        public StaticSpring(int pref) {
            this(pref, pref, pref);
        }

        public StaticSpring(int min, int pref, int max) {
            this.min = min;
            this.pref = pref;
            this.max = max;
        }

         public String toString() {
             return "StaticSpring [" + min + ", " + pref + ", " + max + "]";
         }

         public int getMinimumValue() {
            return min;
        }

        public int getPreferredValue() {
            return pref;
        }

        public int getMaximumValue() {
            return max;
        }
    }

    private static class NegativeSpring extends Spring {
        private Spring s;

        public NegativeSpring(Spring s) {
            this.s = s;
        }

// Note the use of max value rather than minimum value here.
// See the opening preamble on arithmetic with springs.

        public int getMinimumValue() {
            return -s.getMaximumValue();
        }

        public int getPreferredValue() {
            return -s.getPreferredValue();
        }

        public int getMaximumValue() {
            return -s.getMinimumValue();
        }

        public int getValue() {
            return -s.getValue();
        }

        public void setValue(int size) {
            // No need to check for UNSET as
            // Integer.MIN_VALUE == -Integer.MIN_VALUE.
            s.setValue(-size);
        }

        /*pp*/ boolean isCyclic(SpringLayout l) {
            return s.isCyclic(l);
        }
    }

    private static class ScaleSpring extends Spring {
        private Spring s;
        private float factor;

        private ScaleSpring(Spring s, float factor) {
            this.s = s;
            this.factor = factor;
        }

        public int getMinimumValue() {
            return Math.round((factor < 0 ? s.getMaximumValue() : s.getMinimumValue()) * factor);
        }

        public int getPreferredValue() {
            return Math.round(s.getPreferredValue() * factor);
        }

        public int getMaximumValue() {
            return Math.round((factor < 0 ? s.getMinimumValue() : s.getMaximumValue()) * factor);
        }

        public int getValue() {
            return Math.round(s.getValue() * factor);
        }

        public void setValue(int value) {
            if (value == UNSET) {
                s.setValue(UNSET);
            } else {
                s.setValue(Math.round(value / factor));
            }
        }

        /*pp*/ boolean isCyclic(SpringLayout l) {
            return s.isCyclic(l);
        }
    }

    /*pp*/ static class WidthSpring extends AbstractSpring {
        /*pp*/ Component c;

        public WidthSpring(Component c) {
            this.c = c;
        }

        public int getMinimumValue() {
            return c.getMinimumSize().width;
        }

        public int getPreferredValue() {
            return c.getPreferredSize().width;
        }

        public int getMaximumValue() {
            // We will be doing arithmetic with the results of this call,
            // so if a returned value is Integer.MAX_VALUE we will get
            // arithmetic overflow. Truncate such values.
            return Math.min(Short.MAX_VALUE, c.getMaximumSize().width);
        }
    }

     /*pp*/  static class HeightSpring extends AbstractSpring {
        /*pp*/ Component c;

        public HeightSpring(Component c) {
            this.c = c;
        }

        public int getMinimumValue() {
            return c.getMinimumSize().height;
        }

        public int getPreferredValue() {
            return c.getPreferredSize().height;
        }

        public int getMaximumValue() {
            return Math.min(Short.MAX_VALUE, c.getMaximumSize().height);
        }
    }

   /*pp*/ static abstract class SpringMap extends Spring {
       private Spring s;

       public SpringMap(Spring s) {
           this.s = s;
       }

       protected abstract int map(int i);

       protected abstract int inv(int i);

       public int getMinimumValue() {
           return map(s.getMinimumValue());
       }

       public int getPreferredValue() {
           return map(s.getPreferredValue());
       }

       public int getMaximumValue() {
           return Math.min(Short.MAX_VALUE, map(s.getMaximumValue()));
       }

       public int getValue() {
           return map(s.getValue());
       }

       public void setValue(int value) {
           if (value == UNSET) {
               s.setValue(UNSET);
           } else {
               s.setValue(inv(value));
           }
       }

       /*pp*/ boolean isCyclic(SpringLayout l) {
           return s.isCyclic(l);
       }
   }

// Use the instance variables of the StaticSpring superclass to
// cache values that have already been calculated.
    /*pp*/ static abstract class CompoundSpring extends StaticSpring {
        protected Spring s1;
        protected Spring s2;

        public CompoundSpring(Spring s1, Spring s2) {
            super(UNSET);
            this.s1 = s1;
            this.s2 = s2;
        }

        public String toString() {
            return "CompoundSpring of " + s1 + " and " + s2;
        }

        protected void clear() {
            super.clear();
            min = pref = max = UNSET;
            s1.setValue(UNSET);
            s2.setValue(UNSET);
        }

        protected abstract int op(int x, int y);

        public int getMinimumValue() {
            if (min == UNSET) {
                min = op(s1.getMinimumValue(), s2.getMinimumValue());
            }
            return min;
        }

        public int getPreferredValue() {
            if (pref == UNSET) {
                pref = op(s1.getPreferredValue(), s2.getPreferredValue());
            }
            return pref;
        }

        public int getMaximumValue() {
            if (max == UNSET) {
                max = op(s1.getMaximumValue(), s2.getMaximumValue());
            }
            return max;
        }

        public int getValue() {
            if (size == UNSET) {
                size = op(s1.getValue(), s2.getValue());
            }
            return size;
        }

        /*pp*/ boolean isCyclic(SpringLayout l) {
            return l.isCyclic(s1) || l.isCyclic(s2);
        }
    };

     private static class SumSpring extends CompoundSpring {
         public SumSpring(Spring s1, Spring s2) {
             super(s1, s2);
         }

         protected int op(int x, int y) {
             return x + y;
         }

         protected void setNonClearValue(int size) {
             super.setNonClearValue(size);
             s1.setStrain(this.getStrain());
             s2.setValue(size - s1.getValue());
         }
     }

    private static class MaxSpring extends CompoundSpring {

        public MaxSpring(Spring s1, Spring s2) {
            super(s1, s2);
        }

        protected int op(int x, int y) {
            return Math.max(x, y);
        }

        protected void setNonClearValue(int size) {
            super.setNonClearValue(size);
            s1.setValue(size);
            s2.setValue(size);
        }
    }

    
Returns a strut -- a spring whose minimum, preferred, and
maximum values each have the value pref.

Params:
  • pref – the minimum, preferred, and
        maximum values of the new spring
See Also:
Returns:a spring whose minimum, preferred, and
        maximum values each have the value pref
/**
     * Returns a strut -- a spring whose <em>minimum</em>, <em>preferred</em>, and
     * <em>maximum</em> values each have the value <code>pref</code>.
     *
     * @param  pref the <em>minimum</em>, <em>preferred</em>, and
     *         <em>maximum</em> values of the new spring
     * @return a spring whose <em>minimum</em>, <em>preferred</em>, and
     *         <em>maximum</em> values each have the value <code>pref</code>
     *
     * @see Spring
     */
     public static Spring constant(int pref) {
         return constant(pref, pref, pref);
     }

    
Returns a spring whose minimum, preferred, and
maximum values have the values: min, pref,
and max respectively.

Params:
  • min – the minimum value of the new spring
  • pref – the preferred value of the new spring
  • max – the maximum value of the new spring
See Also:
Returns:a spring whose minimum, preferred, and
        maximum values have the values: min, pref,
        and max respectively
/**
     * Returns a spring whose <em>minimum</em>, <em>preferred</em>, and
     * <em>maximum</em> values have the values: <code>min</code>, <code>pref</code>,
     * and <code>max</code> respectively.
     *
     * @param  min the <em>minimum</em> value of the new spring
     * @param  pref the <em>preferred</em> value of the new spring
     * @param  max the <em>maximum</em> value of the new spring
     * @return a spring whose <em>minimum</em>, <em>preferred</em>, and
     *         <em>maximum</em> values have the values: <code>min</code>, <code>pref</code>,
     *         and <code>max</code> respectively
     *
     * @see Spring
     */
     public static Spring constant(int min, int pref, int max) {
         return new StaticSpring(min, pref, max);
     }


    
Returns -s: a spring running in the opposite direction to s.

See Also:
Returns:-s: a spring running in the opposite direction to s
/**
     * Returns <code>-s</code>: a spring running in the opposite direction to <code>s</code>.
     *
     * @return <code>-s</code>: a spring running in the opposite direction to <code>s</code>
     *
     * @see Spring
     */
    public static Spring minus(Spring s) {
        return new NegativeSpring(s);
    }

    
Returns s1+s2: a spring representing s1 and s2
in series. In a sum, s3, of two springs, s1 and s2,
the strains of s1, s2, and s3 are maintained
at the same level (to within the precision implied by their integer values).
The strain of a spring in compression is:

        value - pref
        ------------
         pref - min


and the strain of a spring in tension is:

        value - pref
        ------------
         max - pref


When setValue is called on the sum spring, s3, the strain
in s3 is calculated using one of the formulas above. Once the strain of
the sum is known, the values of s1 and s2 are
then set so that they are have a strain equal to that of the sum. The formulas are
evaluated so as to take rounding errors into account and ensure that the sum of
the values of s1 and s2 is exactly equal to
the value of s3.

See Also:
Returns:s1+s2: a spring representing s1 and s2 in series
/**
     * Returns <code>s1+s2</code>: a spring representing <code>s1</code> and <code>s2</code>
     * in series. In a sum, <code>s3</code>, of two springs, <code>s1</code> and <code>s2</code>,
     * the <em>strains</em> of <code>s1</code>, <code>s2</code>, and <code>s3</code> are maintained
     * at the same level (to within the precision implied by their integer <em>value</em>s).
     * The strain of a spring in compression is:
     * <pre>
     *         value - pref
     *         ------------
     *          pref - min
     * </pre>
     * and the strain of a spring in tension is:
     * <pre>
     *         value - pref
     *         ------------
     *          max - pref
     * </pre>
     * When <code>setValue</code> is called on the sum spring, <code>s3</code>, the strain
     * in <code>s3</code> is calculated using one of the formulas above. Once the strain of
     * the sum is known, the <em>value</em>s of <code>s1</code> and <code>s2</code> are
     * then set so that they are have a strain equal to that of the sum. The formulas are
     * evaluated so as to take rounding errors into account and ensure that the sum of
     * the <em>value</em>s of <code>s1</code> and <code>s2</code> is exactly equal to
     * the <em>value</em> of <code>s3</code>.
     *
     * @return <code>s1+s2</code>: a spring representing <code>s1</code> and <code>s2</code> in series
     *
     * @see Spring
     */
     public static Spring sum(Spring s1, Spring s2) {
         return new SumSpring(s1, s2);
     }

    
Returns max(s1, s2): a spring whose value is always greater than (or equal to)
        the values of both s1 and s2.

See Also:
Returns:max(s1, s2): a spring whose value is always greater than (or equal to)
        the values of both s1 and s2
/**
     * Returns <code>max(s1, s2)</code>: a spring whose value is always greater than (or equal to)
     *         the values of both <code>s1</code> and <code>s2</code>.
     *
     * @return <code>max(s1, s2)</code>: a spring whose value is always greater than (or equal to)
     *         the values of both <code>s1</code> and <code>s2</code>
     * @see Spring
     */
    public static Spring max(Spring s1, Spring s2) {
        return new MaxSpring(s1, s2);
    }

    // Remove these, they're not used often and can be created using minus -
    // as per these implementations.

    /*pp*/ static Spring difference(Spring s1, Spring s2) {
        return sum(s1, minus(s2));
    }

    /*
    public static Spring min(Spring s1, Spring s2) {
        return minus(max(minus(s1), minus(s2)));
    }
    */

    
Returns a spring whose minimum, preferred, maximum
and value properties are each multiples of the properties of the
argument spring, s. Minimum and maximum properties are
swapped when factor is negative (in accordance with the
rules of interval arithmetic).


When factor is, for example, 0.5f the result represents 'the mid-point'
of its input - an operation that is useful for centering components in
a container.

Params:
  • s – the spring to scale
  • factor – amount to scale by.
Throws:
Returns: a spring whose properties are those of the input spring s
multiplied by factor
Since:1.5
/**
     * Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
     * and <em>value</em> properties are each multiples of the properties of the
     * argument spring, <code>s</code>. Minimum and maximum properties are
     * swapped when <code>factor</code> is negative (in accordance with the
     * rules of interval arithmetic).
     * <p>
     * When factor is, for example, 0.5f the result represents 'the mid-point'
     * of its input - an operation that is useful for centering components in
     * a container.
     *
     * @param s the spring to scale
     * @param factor amount to scale by.
     * @return  a spring whose properties are those of the input spring <code>s</code>
     * multiplied by <code>factor</code>
     * @throws NullPointerException if <code>s</code> is null
     * @since 1.5
     */
    public static Spring scale(Spring s, float factor) {
        checkArg(s);
        return new ScaleSpring(s, factor);
    }

    
Returns a spring whose minimum, preferred, maximum
and value properties are defined by the widths of the minimumSize,
preferredSize, maximumSize and size properties
of the supplied component. The returned spring is a 'wrapper' implementation
whose methods call the appropriate size methods of the supplied component.
The minimum, preferred, maximum and value properties of the returned spring
therefore report the current state of the appropriate properties in the
component and track them as they change.

Params:
  • c – Component used for calculating size
Throws:
Returns: a spring whose properties are defined by the horizontal component
of the component's size methods.
Since:1.5
/**
     * Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
     * and <em>value</em> properties are defined by the widths of the <em>minimumSize</em>,
     * <em>preferredSize</em>, <em>maximumSize</em> and <em>size</em> properties
     * of the supplied component. The returned spring is a 'wrapper' implementation
     * whose methods call the appropriate size methods of the supplied component.
     * The minimum, preferred, maximum and value properties of the returned spring
     * therefore report the current state of the appropriate properties in the
     * component and track them as they change.
     *
     * @param c Component used for calculating size
     * @return  a spring whose properties are defined by the horizontal component
     * of the component's size methods.
     * @throws NullPointerException if <code>c</code> is null
     * @since 1.5
     */
    public static Spring width(Component c) {
        checkArg(c);
        return new WidthSpring(c);
    }

    
Returns a spring whose minimum, preferred, maximum
and value properties are defined by the heights of the minimumSize,
preferredSize, maximumSize and size properties
of the supplied component. The returned spring is a 'wrapper' implementation
whose methods call the appropriate size methods of the supplied component.
The minimum, preferred, maximum and value properties of the returned spring
therefore report the current state of the appropriate properties in the
component and track them as they change.

Params:
  • c – Component used for calculating size
Throws:
Returns: a spring whose properties are defined by the vertical component
of the component's size methods.
Since:1.5
/**
     * Returns a spring whose <em>minimum</em>, <em>preferred</em>, <em>maximum</em>
     * and <em>value</em> properties are defined by the heights of the <em>minimumSize</em>,
     * <em>preferredSize</em>, <em>maximumSize</em> and <em>size</em> properties
     * of the supplied component. The returned spring is a 'wrapper' implementation
     * whose methods call the appropriate size methods of the supplied component.
     * The minimum, preferred, maximum and value properties of the returned spring
     * therefore report the current state of the appropriate properties in the
     * component and track them as they change.
     *
     * @param c Component used for calculating size
     * @return  a spring whose properties are defined by the vertical component
     * of the component's size methods.
     * @throws NullPointerException if <code>c</code> is null
     * @since 1.5
     */
    public static Spring height(Component c) {
        checkArg(c);
        return new HeightSpring(c);
    }


    
If s is null, this throws an NullPointerException.

/**
     * If <code>s</code> is null, this throws an NullPointerException.
     */
    private static void checkArg(Object s) {
        if (s == null) {
            throw new NullPointerException("Argument must not be null");
        }
    }
}