54 lines
1.5 KiB
Java
54 lines
1.5 KiB
Java
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abstract class AbstractStringBuilder {
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char value[];
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int count;
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public AbstractStringBuilder(int capacity) {
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value = new char[capacity];
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}
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public AbstractStringBuilder append(CharSequence s, int start, int end) {
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if (s == null)
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s = "null";
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if ((start < 0) || (end < 0) || (start > end) || (end > s.length()))
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throw new IndexOutOfBoundsException(
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"start " + start + ", end " + end + ", s.length() "
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+ s.length());
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int len = end - start;
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if (len == 0)
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return this;
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int newCount = count + len;
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if (newCount > value.length)
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expandCapacity(newCount);
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for (int i=start; i<end; i++)
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value[count++] = s.charAt(i);
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count = newCount;
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return this;
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}
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void expandCapacity(int minimumCapacity) {
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int newCapacity = (value.length + 1) * 2;
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if (newCapacity < 0) {
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newCapacity = Integer.MAX_VALUE;
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} else if (minimumCapacity > newCapacity) {
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newCapacity = minimumCapacity;
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}
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value = Arrays.copyOf(value, newCapacity);
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}
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public int capacity() {
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return value.length;
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}
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public abstract String toString();
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}
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class StringBuilder extends AbstractStringBuilder {
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public StringBuilder(int capacity) {
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super(capacity);
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}
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public String toString() {
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return new String(value, 0, count);
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}
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}
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