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## com.google.common.base
Class Strings

    java.lang.Object
      com.google.common.base.Strings

    @GwtCompatible
    public final class Strings

extends Object

Static utility methods pertaining to `String` or `CharSequence` instances.

Since:
  3.0
Author:
  Kevin Bourrillion

Method Summary
`static String` | `commonPrefix(CharSequence a, CharSequence b)` Returns the longest string `prefix` such that `a.toString().startsWith(prefix) && b.toString().startsWith(prefix)`, taking care not to split surrogate pairs.
`static String` | `commonSuffix(CharSequence a, CharSequence b)` Returns the longest string `suffix` such that `a.toString().endsWith(suffix) && b.toString().endsWith(suffix)`, taking care not to split surrogate pairs.
`static String` | `emptyToNull(String string)` Returns the given string if it is nonempty; `null` otherwise.
`static boolean` | `isNullOrEmpty(String string)` Returns `true` if the given string is null or is the empty string.
`static String` | `nullToEmpty(String string)` Returns the given string if it is non-null; the empty string otherwise.
`static String` | `padEnd(String string, int minLength, char padChar)` Returns a string, of length at least `minLength`, consisting of `string` appended with as many copies of `padChar` as are necessary to reach that length.
`static String` | `padStart(String string, int minLength, char padChar)` Returns a string, of length at least `minLength`, consisting of `string` prepended with as many copies of `padChar` as are necessary to reach that length.
`static String` | `repeat(String string, int count)` Returns a string consisting of a specific number of concatenated copies of an input string.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Method Detail

### nullToEmpty

    public static String nullToEmpty(@Nullable
                                     String string)

  Returns the given string if it is non-null; the empty string otherwise.

  Parameters:
    `string` - the string to test and possibly return
  Returns:
    `string` itself if it is non-null; `""` if it is null

### emptyToNull

    @Nullable
    public static String emptyToNull(@Nullable
                                              String string)

  Returns the given string if it is nonempty; `null` otherwise.

  Parameters:
    `string` - the string to test and possibly return
  Returns:
    `string` itself if it is nonempty; `null` if it is empty or null

### isNullOrEmpty

    public static boolean isNullOrEmpty(@Nullable
                                        String string)

  Returns `true` if the given string is null or is the empty string.

  Consider normalizing your string references with `nullToEmpty(java.lang.String)`. If you do, you can use `String.isEmpty()` instead of this method, and you won't need special null-safe forms of methods like `String.toUpperCase(java.util.Locale)` either. Or, if you'd like to normalize "in the other direction," converting empty strings to `null`, you can use `emptyToNull(java.lang.String)`.

  Parameters:
    `string` - a string reference to check
  Returns:
    `true` if the string is null or is the empty string

### padStart

    public static String padStart(String string,
                                  int minLength,
                                  char padChar)

  Returns a string, of length at least `minLength`, consisting of `string` prepended with as many copies of `padChar` as are necessary to reach that length. For example,
  - `padStart("7", 3, '0')` returns `"007"`
  - `padStart("2010", 3, '0')` returns `"2010"`

  See `Formatter` for a richer set of formatting capabilities.

  Parameters:
    `string` - the string which should appear at the end of the result
    `minLength` - the minimum length the resulting string must have. Can be zero or negative, in which case the input string is always returned.
    `padChar` - the character to insert at the beginning of the result until the minimum length is reached
  Returns:
    the padded string

### padEnd

    public static String padEnd(String string,
                                int minLength,
                                char padChar)

  Returns a string, of length at least `minLength`, consisting of `string` appended with as many copies of `padChar` as are necessary to reach that length. For example,
  - `padEnd("4.", 5, '0')` returns `"4.000"`
  - `padEnd("2010", 3, '!')` returns `"2010"`

  See `Formatter` for a richer set of formatting capabilities.

  Parameters:
    `string` - the string which should appear at the beginning of the result
    `minLength` - the minimum length the resulting string must have. Can be zero or negative, in which case the input string is always returned.
    `padChar` - the character to append to the end of the result until the minimum length is reached
  Returns:
    the padded string

### repeat

    public static String repeat(String string,
                                int count)

  Returns a string consisting of a specific number of concatenated copies of an input string. For example, `repeat("hey", 3)` returns the string `"heyheyhey"`.

  Parameters:
    `string` - any non-null string
    `count` - the number of times to repeat it; a nonnegative integer
  Returns:
    a string containing `string` repeated `count` times (the empty string if `count` is zero)
  Throws:
    `IllegalArgumentException` - if `count` is negative

### commonPrefix

    public static String commonPrefix(CharSequence a,
                                      CharSequence b)

  Returns the longest string `prefix` such that `a.toString().startsWith(prefix) && b.toString().startsWith(prefix)`, taking care not to split surrogate pairs. If `a` and `b` have no common prefix, returns the empty string.

  Since:
    11.0

### commonSuffix

    public static String commonSuffix(CharSequence a,
                                      CharSequence b)

  Returns the longest string `suffix` such that `a.toString().endsWith(suffix) && b.toString().endsWith(suffix)`, taking care not to split surrogate pairs. If `a` and `b` have no common suffix, returns the empty string.

  Since:
    11.0

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