+ * Note that this container keeps its mappings in an array data structure, using + * a binary search to find keys. The implementation is not intended to be + * appropriate for data structures that may contain large numbers of items. It + * is generally slower than a traditional HashMap, since lookups require a + * binary search and adds and removes require inserting and deleting entries in + * the array. For containers holding up to hundreds of items, the performance + * difference is not significant, less than 50%. + *
+ * + *
+ * It is possible to iterate over the items in this container using
+ * {@link #keyAt(int)} and {@link #valueAt(int)}. Iterating over the keys using
+ * keyAt(int) with ascending values of the index will return the
+ * keys in ascending order, or the values corresponding to the keys in ascending
+ * order in the case of valueAt(int).
+ *
0 if no such
+ * mapping has been made.
+ */
+ public int get(int key)
+ {
+ return get(key, 0);
+ }
+
+ /**
+ * Gets the int mapped from the specified key, or the specified value if no
+ * such mapping has been made.
+ */
+ public int get(int key, int valueIfKeyNotFound)
+ {
+ int i = ContainerHelpers.binarySearch(mKeys, mSize, key);
+ if (i < 0)
+ {
+ return valueIfKeyNotFound;
+ }
+ else
+ {
+ return mValues[i];
+ }
+ }
+
+ /**
+ * Removes the mapping from the specified key, if there was any.
+ */
+ public void delete(int key)
+ {
+ int i = ContainerHelpers.binarySearch(mKeys, mSize, key);
+ if (i >= 0)
+ {
+ removeAt(i);
+ }
+ }
+
+ /**
+ * Removes the mapping at the given index.
+ */
+ public void removeAt(int index)
+ {
+ System.arraycopy(mKeys, index + 1, mKeys, index, mSize - (index + 1));
+ System.arraycopy(mValues, index + 1, mValues, index, mSize
+ - (index + 1));
+ mSize--;
+ }
+
+ /**
+ * Adds a mapping from the specified key to the specified value, replacing the
+ * previous mapping from the specified key if there was one.
+ */
+ public void put(int key, int value)
+ {
+ int i = ContainerHelpers.binarySearch(mKeys, mSize, key);
+ if (i >= 0)
+ {
+ mValues[i] = value;
+ }
+ else
+ {
+ i = ~i;
+ if (mSize >= mKeys.length)
+ {
+ int n = idealIntArraySize(mSize + 1);
+ int[] nkeys = new int[n];
+ int[] nvalues = new int[n];
+ // Log.e("SparseIntArray", "grow " + mKeys.length + " to " + n);
+ System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
+ System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
+ mKeys = nkeys;
+ mValues = nvalues;
+ }
+ if (mSize - i != 0)
+ {
+ // Log.e("SparseIntArray", "move " + (mSize - i));
+ System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i);
+ System.arraycopy(mValues, i, mValues, i + 1, mSize - i);
+ }
+ mKeys[i] = key;
+ mValues[i] = value;
+ mSize++;
+ }
+ }
+
+ /**
+ * Returns the number of key-value mappings that this SparseIntArray currently
+ * stores.
+ */
+ public int size()
+ {
+ return mSize;
+ }
+
+ /**
+ * Given an index in the range 0...size()-1, returns the key from
+ * the indexth key-value mapping that this SparseIntArray stores.
+ *
+ *
+ * The keys corresponding to indices in ascending order are guaranteed to be
+ * in ascending order, e.g., keyAt(0) will return the smallest
+ * key and keyAt(size()-1) will return the largest key.
+ *
0...size()-1, returns the value
+ * from the indexth key-value mapping that this SparseIntArray
+ * stores.
+ *
+ *
+ * The values corresponding to indices in ascending order are guaranteed to be
+ * associated with keys in ascending order, e.g., valueAt(0) will
+ * return the value associated with the smallest key and
+ * valueAt(size()-1) will return the value associated with the
+ * largest key.
+ *
+ * This implementation composes a string by iterating over its mappings. + */ + @Override + public String toString() + { + if (size() <= 0) + { + return "{}"; + } + StringBuilder buffer = new StringBuilder(mSize * 28); + buffer.append('{'); + for (int i = 0; i < mSize; i++) + { + if (i > 0) + { + buffer.append(", "); + } + int key = keyAt(i); + buffer.append(key); + buffer.append('='); + int value = valueAt(i); + buffer.append(value); + } + buffer.append('}'); + return buffer.toString(); + } + + /** + * Method (copied from put) added for Jalview to efficiently increment a key's + * value if present, else add it with the given value. This avoids a double + * binary search (once to get the value, again to put the updated value). + * + * @param key + * @oparam toAdd + * @return the new value of the count for the key + * @throw ArithmeticException if the result would exceed the maximum value of + * an int + */ + public int add(int key, int toAdd) + { + int newValue = toAdd; + int i = ContainerHelpers.binarySearch(mKeys, mSize, key); + if (i >= 0) + { + checkOverflow(mValues[i], toAdd); + mValues[i] += toAdd; + newValue = mValues[i]; + } + else + { + i = ~i; + if (mSize >= mKeys.length) + { + int n = idealIntArraySize(mSize + 1); + int[] nkeys = new int[n]; + int[] nvalues = new int[n]; + System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length); + System.arraycopy(mValues, 0, nvalues, 0, mValues.length); + mKeys = nkeys; + mValues = nvalues; + } + if (mSize - i != 0) + { + System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i); + System.arraycopy(mValues, i, mValues, i + 1, mSize - i); + } + mKeys[i] = key; + mValues[i] = toAdd; + mSize++; + } + return newValue; + } + + /** + * Throws ArithmeticException if adding addend to value would exceed the range + * of int + * + * @param value + * @param addend + */ + static void checkOverflow(int value, int addend) + { + /* + * test cases being careful to avoid overflow while testing! + */ + if (addend > 0) + { + if (value > 0 && Integer.MAX_VALUE - value < addend) + { + throw new ArithmeticException("Integer overflow adding " + addend + + " to " + value); + } + } + else if (addend < 0) + { + if (value < 0 && Integer.MIN_VALUE - value > addend) + { + throw new ArithmeticException("Integer underflow adding " + addend + + " to " + value); + } + } + } +}