OpenJDK 27 · javax.swing.SizeSequence · APIdia, the JavaDoc alternative

A SizeSequence object efficiently maintains an ordered list of sizes and corresponding positions. One situation for which SizeSequence might be appropriate is in a component that displays multiple rows of unequal size. In this case, a single SizeSequence object could be used to track the heights and Y positions of all rows.

Another example would be a multi-column component, such as a JTable, in which the column sizes are not all equal. The JTable might use a single SizeSequence object to store the widths and X positions of all the columns. The JTable could then use the SizeSequence object to find the column corresponding to a certain position. The JTable could update the SizeSequence object whenever one or more column sizes changed.

The following figure shows the relationship between size and position data for a multi-column component.

The first item begins at position 0, the second at the position equal
to the size of the previous item, and so on.

In the figure, the first index (0) corresponds to the first column, the second index (1) to the second column, and so on. The first column's position starts at 0, and the column occupies size₀ pixels, where size₀ is the value returned by getSize(0). Thus, the first column ends at size₀ - 1. The second column then begins at the position size₀ and occupies size₁ (getSize(1)) pixels.

Note that a SizeSequence object simply represents intervals along an axis. In our examples, the intervals represent height or width in pixels. However, any other unit of measure (for example, time in days) could be just as valid.

Implementation Notes

Normally when storing the size and position of entries, one would choose between storing the sizes or storing their positions instead. The two common operations that are needed during rendering are: getIndex(position) and setSize(index, size). Whichever choice of internal format is made one of these operations is costly when the number of entries becomes large. If sizes are stored, finding the index of the entry that encloses a particular position is linear in the number of entries. If positions are stored instead, setting the size of an entry at a particular index requires updating the positions of the affected entries, which is also a linear calculation.

Like the above techniques this class holds an array of N integers internally but uses a hybrid encoding, which is halfway between the size-based and positional-based approaches. The result is a data structure that takes the same space to store the information but can perform most operations in Log(N) time instead of O(N), where N is the number of entries in the list.

Two operations that remain O(N) in the number of entries are the insertEntries and removeEntries methods, both of which are implemented by converting the internal array to a set of integer sizes, copying it into the new array, and then reforming the hybrid representation in place.

Field Summary

Modifier and Type	Field and Description
private int[]	a
private static int[]	emptyArray

Constructor Summary

Access	Constructor and Description
public	SizeSequence() Creates a new `SizeSequence` object that contains no entries.
public	SizeSequence(int the number of sizes to track numEntries) Creates a new `SizeSequence` object that contains the specified number of entries, all initialized to have size 0.
public	SizeSequence(int the number of sizes to track numEntries, int the initial value of each size value) Creates a new `SizeSequence` object that contains the specified number of entries, all initialized to have size `value`.
public	SizeSequence(int[] the array of sizes to be contained in the `SizeSequence` sizes) Creates a new `SizeSequence` object that contains the specified sizes.

Method Summary

Modifier and Type	Method and Description
private void	changeSize(int from, int to, int index, int delta)
public int	Returns: the index of the entry that occupies the specified position getIndex(int the position of the entry position) Returns the index of the entry that corresponds to the specified position.
private int	getIndex(int from, int to, int position)
public int	Returns: the starting position of the specified entry getPosition(int the index of the entry whose position is desired index) Returns the start position for the specified entry.
private int	getPosition(int from, int to, int index)
public int	Returns: the size of the entry getSize(int the index corresponding to the entry index) Returns the size of the specified entry.
public int[]	Returns: a new array containing the sizes in this object getSizes() Returns the size of all entries.
private int	getSizes(int from, int to, int[] sizes)
public void	insertEntries(int the index to be assigned to the first entry in the group start, int the number of entries in the group length, int the size to be assigned to each new entry value) Adds a contiguous group of entries to this `SizeSequence`.
public void	removeEntries(int the index of the first entry to be removed start, int the number of entries to be removed length) Removes a contiguous group of entries from this `SizeSequence`.
public void	setSize(int the index corresponding to the entry index, int the size of the entry size) Sets the size of the specified entry.
pack-priv void	setSizes(int length, int size) Resets the size sequence to contain `length` items all with a size of `size`.
private int	setSizes(int from, int to, int size)
public void	setSizes(int[] the array of sizes to be contained in this `SizeSequence` sizes) Resets this `SizeSequence` object, using the data in the `sizes` argument.
private int	setSizes(int from, int to, int[] sizes)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

a	back to summary
private int[] a

emptyArray	back to summary
private static int[] emptyArray

Constructor Detail

SizeSequence back to summary

SizeSequence	back to summary
public SizeSequence() Creates a new `SizeSequence` object that contains no entries. To add entries, you can use `insertEntries` or `setSizes`. See Also `insertEntries`, `setSizes(int[])`

public SizeSequence()

Creates a new SizeSequence object that contains no entries. To add entries, you can use insertEntries or setSizes.

See Also: insertEntries, setSizes(int[])

SizeSequence back to summary

SizeSequence	back to summary
public SizeSequence(int numEntries) Creates a new `SizeSequence` object that contains the specified number of entries, all initialized to have size 0. Parameters numEntries:int the number of sizes to track Exceptions NegativeArraySizeException: if `numEntries < 0`

public SizeSequence(int numEntries)

Creates a new SizeSequence object that contains the specified number of entries, all initialized to have size 0.

Parameters

numEntries:int: the number of sizes to track

Exceptions

NegativeArraySizeException:: if numEntries < 0

SizeSequence back to summary

SizeSequence	back to summary
public SizeSequence(int numEntries, int value) Creates a new `SizeSequence` object that contains the specified number of entries, all initialized to have size `value`. Parameters numEntries:int the number of sizes to track value:int the initial value of each size

public SizeSequence(int numEntries, int value)

Creates a new SizeSequence object that contains the specified number of entries, all initialized to have size value.

Parameters

numEntries:int: the number of sizes to track
value:int: the initial value of each size

SizeSequence back to summary

SizeSequence	back to summary
public SizeSequence(int[] sizes) Creates a new `SizeSequence` object that contains the specified sizes. Parameters sizes:int[] the array of sizes to be contained in the `SizeSequence`

public SizeSequence(int[] sizes)

Creates a new SizeSequence object that contains the specified sizes.

Parameters

sizes:int[]: the array of sizes to be contained in the SizeSequence

Method Detail

changeSize	back to summary
private void changeSize(int from, int to, int index, int delta)

getIndex back to summary

getIndex	back to summary
public int getIndex(int position) Returns the index of the entry that corresponds to the specified position. For example, `getIndex(0)` is 0, since the first entry always starts at position 0. Parameters position:int the position of the entry Returns:int the index of the entry that occupies the specified position

public int getIndex(int position)

Returns the index of the entry that corresponds to the specified position. For example, getIndex(0) is 0, since the first entry always starts at position 0.

Parameters

position:int: the position of the entry

Returns:int

the index of the entry that occupies the specified position

getIndex	back to summary
private int getIndex(int from, int to, int position)

getPosition back to summary

getPosition	back to summary
public int getPosition(int index) Returns the start position for the specified entry. For example, `getPosition(0)` returns 0, `getPosition(1)` is equal to `getSize(0)`, `getPosition(2)` is equal to `getSize(0)` + `getSize(1)`, and so on. Note that if `index` is greater than `length` the value returned may be meaningless. Parameters index:int the index of the entry whose position is desired Returns:int the starting position of the specified entry

public int getPosition(int index)

Returns the start position for the specified entry. For example, getPosition(0) returns 0, getPosition(1) is equal to getSize(0), getPosition(2) is equal to getSize(0) + getSize(1), and so on.

Note that if index is greater than length the value returned may be meaningless.

Parameters

index:int: the index of the entry whose position is desired

Returns:int

the starting position of the specified entry

getPosition	back to summary
private int getPosition(int from, int to, int index)

getSize back to summary

getSize	back to summary
public int getSize(int index) Returns the size of the specified entry. If `index` is out of the range `(0 <= index < getSizes().length)` the behavior is unspecified. Parameters index:int the index corresponding to the entry Returns:int the size of the entry

public int getSize(int index)

Returns the size of the specified entry. If index is out of the range (0 <= index < getSizes().length) the behavior is unspecified.

Parameters

index:int: the index corresponding to the entry

Returns:int

the size of the entry

getSizes	back to summary
public int[] getSizes() Returns the size of all entries. Returns:int[] a new array containing the sizes in this object

getSizes

back to summary

public int[] getSizes()

Returns the size of all entries.

Returns:int[]: a new array containing the sizes in this object

getSizes	back to summary
private int getSizes(int from, int to, int[] sizes)

insertEntries back to summary

insertEntries	back to summary
public void insertEntries(int start, int length, int value) Adds a contiguous group of entries to this `SizeSequence`. Note that the values of `start` and `length` must satisfy the following conditions: `(0 <= start < getSizes().length) AND (length >= 0)`. If these conditions are not met, the behavior is unspecified and an exception may be thrown. Parameters start:int the index to be assigned to the first entry in the group length:int the number of entries in the group value:int the size to be assigned to each new entry Exceptions ArrayIndexOutOfBoundsException: if the parameters are outside of the range: (`0 <= start < (getSizes().length)) AND (length >= 0)`

public void insertEntries(int start, int length, int value)

Adds a contiguous group of entries to this SizeSequence. Note that the values of start and length must satisfy the following conditions: (0 <= start < getSizes().length) AND (length >= 0). If these conditions are not met, the behavior is unspecified and an exception may be thrown.

Parameters

start:int: the index to be assigned to the first entry in the group
length:int: the number of entries in the group
value:int: the size to be assigned to each new entry

Exceptions

ArrayIndexOutOfBoundsException:: if the parameters are outside of the range: (0 <= start < (getSizes().length)) AND (length >= 0)

removeEntries back to summary

removeEntries	back to summary
public void removeEntries(int start, int length) Removes a contiguous group of entries from this `SizeSequence`. Note that the values of `start` and `length` must satisfy the following conditions: `(0 <= start < getSizes().length) AND (length >= 0)`. If these conditions are not met, the behavior is unspecified and an exception may be thrown. Parameters start:int the index of the first entry to be removed length:int the number of entries to be removed

public void removeEntries(int start, int length)

Removes a contiguous group of entries from this SizeSequence. Note that the values of start and length must satisfy the following conditions: (0 <= start < getSizes().length) AND (length >= 0). If these conditions are not met, the behavior is unspecified and an exception may be thrown.

Parameters

start:int: the index of the first entry to be removed
length:int: the number of entries to be removed

setSize back to summary

setSize	back to summary
public void setSize(int index, int size) Sets the size of the specified entry. Note that if the value of `index` does not fall in the range: `(0 <= index < getSizes().length)` the behavior is unspecified. Parameters index:int the index corresponding to the entry size:int the size of the entry

public void setSize(int index, int size)

Sets the size of the specified entry. Note that if the value of index does not fall in the range: (0 <= index < getSizes().length) the behavior is unspecified.

Parameters

index:int: the index corresponding to the entry
size:int: the size of the entry

setSizes	back to summary
pack-priv void setSizes(int length, int size) Resets the size sequence to contain `length` items all with a size of `size`.

setSizes	back to summary
private int setSizes(int from, int to, int size)

setSizes back to summary

setSizes	back to summary
public void setSizes(int[] sizes) Resets this `SizeSequence` object, using the data in the `sizes` argument. This method reinitializes this object so that it contains as many entries as the `sizes` array. Each entry's size is initialized to the value of the corresponding item in `sizes`. Parameters sizes:int[] the array of sizes to be contained in this `SizeSequence`

public void setSizes(int[] sizes)

Resets this SizeSequence object, using the data in the sizes argument. This method reinitializes this object so that it contains as many entries as the sizes array. Each entry's size is initialized to the value of the corresponding item in sizes.

Parameters

sizes:int[]: the array of sizes to be contained in this SizeSequence

setSizes	back to summary
private int setSizes(int from, int to, int[] sizes)

public Class SizeSequence

Implementation Notes

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail