Some Java String methods

CMPS 134 : Some Java String methods

Letting str and str2 be of type String, k and m be of type int, and ch be of type char, here are examples of invocations of methods in the java.lang.String class:

method
Invocation Return Type Value Returned

str.length() int length of str

str.equals(str2) boolean true if str and str2 are equal (meaning that their values are identical sequences of characters), false otherwise

str.indexOf(ch) int lowest-numbered position in str at which ch occurs, or -1 if there are no occurrences.

str.indexOf(ch,k) int lowest-numbered position not less than k at which ch occurs in str, or -1 if there are no such occurrences.

str.lastIndexOf(ch) int highest-numbered position in str at which ch occurs, or -1 if there are no occurrences.

str.lastIndexOf(ch,k) int highest-numbered position not greater than k at which ch occurs in str, or -1 if there are no such occurrences.

str.substring(k,m) String substring of str extending from position k through position m-1.

str.substring(k) String suffix of str starting at position k.

str.charAt(k) char character at position k of str.

str.concat(str2)
or, equivalently
str + str2 String string that results from concatenating str and str2.

str.trim() String string identical to str except that any leading or trailing whitespace characters (e.g., spaces, tabs) have been removed

str.toUpperCase() String string identical to str except that any lower case letters have been replaced by their upper case counterparts

str.toLowerCase() String string identical to str except that any upper case letters have been replaced by their lower case counterparts

method Invocation	Return Type	Value Returned
`str.length()`	`int`	length of `str`
`str.equals(str2)`	`boolean`	`true` if `str` and `str2` are equal (meaning that their values are identical sequences of characters), `false` otherwise
`str.indexOf(ch)`	`int`	lowest-numbered position in `str` at which `ch` occurs, or -1 if there are no occurrences.
`str.indexOf(ch,k)`	`int`	lowest-numbered position not less than `k` at which `ch` occurs in `str`, or -1 if there are no such occurrences.
`str.lastIndexOf(ch)`	`int`	highest-numbered position in `str` at which `ch` occurs, or -1 if there are no occurrences.
`str.lastIndexOf(ch,k)`	`int`	highest-numbered position not greater than `k` at which `ch` occurs in `str`, or -1 if there are no such occurrences.
`str.substring(k,m)`	`String`	substring of `str` extending from position `k` through position `m-1`.
`str.substring(k)`	`String`	suffix of `str` starting at position `k`.
`str.charAt(k)`	`char`	character at position `k` of `str`.
`str.concat(str2)` or, equivalently `str + str2`	`String`	string that results from concatenating `str` and `str2`.
`str.trim()`	`String`	string identical to `str` except that any leading or trailing whitespace characters (e.g., spaces, tabs) have been removed
`str.toUpperCase()`	`String`	string identical to `str` except that any lower case letters have been replaced by their upper case counterparts
`str.toLowerCase()`	`String`	string identical to `str` except that any upper case letters have been replaced by their lower case counterparts