Stringbuilder API

Question 1

What do the append(…) methods do?

Answer 1

StringBuilder	append(boolean b)
Appends the string representation of the boolean argument to the sequence.

StringBuilder	append(char c)
Appends the string representation of the char argument to this sequence.

StringBuilder	append(char[] str)
Appends the string representation of the char array argument to this sequence.

StringBuilder	append(char[] str, int offset, int len)
Appends the string representation of a subarray of the char array argument to this sequence.

StringBuilder	append(CharSequence s)
Appends the specified character sequence to this Appendable.

StringBuilder	append(CharSequence s, int start, int end)
Appends a subsequence of the specified CharSequence to this sequence.

StringBuilder	append(double d)
Appends the string representation of the double argument to this sequence.

StringBuilder	append(float f)
Appends the string representation of the float argument to this sequence.

StringBuilder	append(int i)
Appends the string representation of the int argument to this sequence.

StringBuilder	append(long lng)
Appends the string representation of the long argument to this sequence.

StringBuilder	append(Object obj)
Appends the string representation of the Object argument.

StringBuilder	append(String str)
Appends the specified string to this character sequence.

StringBuilder	append(StringBuffer sb)
Appends the specified StringBuffer to this sequence.

Question 2

What do
appendCodePoint(i)
codePointAt(i)
codePointBefore(i)
codePointCount(i,j)
do?

Answer 2

appendCodePoint(int codePoint)
Appends the string representation of the codePoint argument to this sequence.

int	codePointAt(int index)
Returns the character (Unicode code point) at the specified index.
int	codePointBefore(int index)
Returns the character (Unicode code point) before the specified index.
int	codePointCount(int beginIndex, int endIndex)
Returns the number of Unicode code points in the specified text range of this sequence.

Question 3

What does capacity() do?

Answer 3

capacity()

Returns the current capacity.

Question 4

What does charAt(i) do?

Answer 4

charAt(int index)

Returns the char value in this sequence at the specified index.

Question 5

What do delete(i, j), deleteCharAt(i) do?

Answer 5

StringBuilder	delete(int start, int end)
Removes the characters in a substring of this sequence.

StringBuilder	deleteCharAt(int index)
Removes the char at the specified position in this sequence.

Question 6

What does ensureCapacity(i) do?

Answer 6

void	ensureCapacity(int minimumCapacity)
Ensures that the capacity is at least equal to the specified minimum.

Question 7

What does getChars(i, j, c[], k) do?

Answer 7

void	getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
Characters are copied from this sequence into the destination character array destination starting at dstbegin.

Question 8

What do indexOf(s), indexOf(s, i) do?

Answer 8

int	indexOf(String str)
Returns the index within this string of the first occurrence of the specified substring.

int	indexOf(String str, int fromIndex)
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.

Question 9

What do insert(…) do?

Answer 9

StringBuilder	insert(int offset, boolean b)
Inserts the string representation of the boolean argument into this sequence.

StringBuilder	insert(int offset, char c)
Inserts the string representation of the char argument into this sequence.

StringBuilder	insert(int offset, char[] str)
Inserts the string representation of the char array argument into this sequence.

StringBuilder	insert(int index, char[] str, int offset, int len)
Inserts the string representation of a subarray of the str array argument into this sequence.

StringBuilder	insert(int dstOffset, CharSequence s)
Inserts the specified CharSequence into this sequence.

StringBuilder	insert(int dstOffset, CharSequence s, int start, int end)
Inserts a subsequence of the specified CharSequence into this sequence.

StringBuilder	insert(int offset, double d)
Inserts the string representation of the double argument into this sequence.

StringBuilder	insert(int offset, float f)
Inserts the string representation of the float argument into this sequence.

StringBuilder	insert(int offset, int i)
Inserts the string representation of the second int argument into this sequence.

StringBuilder	insert(int offset, long l)
Inserts the string representation of the long argument into this sequence.

StringBuilder	insert(int offset, Object obj)
Inserts the string representation of the Object argument into this character sequence.

StringBuilder	insert(int offset, String str)
Inserts the string into this character sequence.

Question 10

What do lastIndexOf(s), lastIndexOf(s,i) do?

Answer 10

int	lastIndexOf(String str)
Returns the index within this string of the rightmost occurrence of the specified substring.

int	lastIndexOf(String str, int fromIndex)
Returns the index within this string of the last occurrence of the specified substring.

Question 11

What does length() do?

Answer 11

length()

Returns the length (character count).

Question 12

What does offsetByCodePoints(i,j) do?

Answer 12

int	offsetByCodePoints(int index, int codePointOffset)
Returns the index within this sequence that is offset from the given index by codePointOffset code points.

Question 13

What does replace(i, j, s) do?

Answer 13

StringBuilder	replace(int start, int end, String str)
Replaces the characters in a substring of this sequence with characters in the specified String.

Question 14

What does reverse() do?

Answer 14

reverse()

Causes this character sequence to be replaced by the reverse of the sequence.

Question 15

What does setCharAt(i, c) do?

Answer 15

void	setCharAt(int index, char ch)
The character at the specified index is set to ch.

Question 16

What does setLength(i do?

Answer 16

void	setLength(int newLength)
Sets the length of the character sequence.

Question 17

What does subSequence(i,j) do?

Answer 17

CharSequence subSequence(int start, int end)
Returns a new character sequence that is a subsequence of this sequence.

Question 18

What do substring(i), substring(i,j) do?

Answer 18

String	substring(int start)
Returns a new String that contains a subsequence of characters currently contained in this character sequence.

String	substring(int start, int end)
Returns a new String that contains a subsequence of characters currently contained in this sequence.

Question 19

What does toString() do?

Answer 19

Returns a string representing the data in this sequence.

Question 20

What does trimToSize() do?

Answer 20

Attempts to reduce storage used for the character sequence.

Question 21

What methods are inherited from java.lang.Object?

Answer 21

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Question 22

What methods are inherited from java.lang.CharSequence?

Answer 22

charAt, length, subSequence