Util (feign-core 8.16.2 API)

java.lang.Object
- feign.Util

```
public class Util
extends java.lang.Object
```
Utilities, typically copied in from guava, so as to avoid dependency conflicts.

Field Summary

Fields
Modifier and Type	Field and Description
`static java.lang.String`	`CONTENT_ENCODING` The HTTP Content-Encoding header field name.
`static java.lang.String`	`CONTENT_LENGTH` The HTTP Content-Length header field name.
`static java.lang.String`	`ENCODING_DEFLATE` Value for the Content-Encoding header that indicates that DEFLATE encoding is in use.
`static java.lang.String`	`ENCODING_GZIP` Value for the Content-Encoding header that indicates that GZIP encoding is in use.
`static java.nio.charset.Charset`	`ISO_8859_1` ISO-8859-1: ISO Latin Alphabet Number 1 (ISO-LATIN-1).
`static java.lang.reflect.Type`	`MAP_STRING_WILDCARD` Type literal for `Map<String, ?>`.
`static java.lang.String`	`RETRY_AFTER` The HTTP Retry-After header field name.
`static java.nio.charset.Charset`	`UTF_8` UTF-8: eight-bit UCS Transformation Format.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static void`	`checkArgument(boolean expression, java.lang.String errorMessageTemplate, java.lang.Object... errorMessageArgs)` Copy of `com.google.common.base.Preconditions#checkArgument`.
`static <T> T`	`checkNotNull(T reference, java.lang.String errorMessageTemplate, java.lang.Object... errorMessageArgs)` Copy of `com.google.common.base.Preconditions#checkNotNull`.
`static void`	`checkState(boolean expression, java.lang.String errorMessageTemplate, java.lang.Object... errorMessageArgs)` Copy of `com.google.common.base.Preconditions#checkState`.
`static java.lang.String`	`emptyToNull(java.lang.String string)` Adapted from `com.google.common.base.Strings#emptyToNull`.
`static java.lang.Object`	`emptyValueOf(java.lang.reflect.Type type)` This returns well known empty values for well-known java types.
`static void`	`ensureClosed(java.io.Closeable closeable)`
`static boolean`	`isDefault(java.lang.reflect.Method method)` Identifies a method as a default instance method.
`static java.lang.reflect.Type`	`resolveLastTypeParameter(java.lang.reflect.Type genericContext, java.lang.Class<?> supertype)` Resolves the last type parameter of the parameterized `supertype`, based on the `genericContext`, into its upper bounds.
`static <T> T[]`	`toArray(java.lang.Iterable<? extends T> iterable, java.lang.Class<T> type)` Adapted from `com.google.common.base.Strings#emptyToNull`.
`static byte[]`	`toByteArray(java.io.InputStream in)` Adapted from `com.google.common.io.ByteStreams.toByteArray()`.
`static java.lang.String`	`toString(java.io.Reader reader)` Adapted from `com.google.common.io.CharStreams.toString()`.
`static <T> java.util.Collection<T>`	`valuesOrEmpty(java.util.Map<java.lang.String,java.util.Collection<T>> map, java.lang.String key)` Returns an unmodifiable collection which may be empty, but is never null.

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

- Field Detail
  - CONTENT_LENGTH
```
public static final java.lang.String CONTENT_LENGTH
```
    The HTTP Content-Length header field name.
    
    See Also:
    
    Constant Field Values
  - CONTENT_ENCODING
```
public static final java.lang.String CONTENT_ENCODING
```
    The HTTP Content-Encoding header field name.
    
    See Also:
    
    Constant Field Values
  - RETRY_AFTER
```
public static final java.lang.String RETRY_AFTER
```
    The HTTP Retry-After header field name.
    
    See Also:
    
    Constant Field Values
  - ENCODING_GZIP
```
public static final java.lang.String ENCODING_GZIP
```
    Value for the Content-Encoding header that indicates that GZIP encoding is in use.
    
    See Also:
    
    Constant Field Values
  - ENCODING_DEFLATE
```
public static final java.lang.String ENCODING_DEFLATE
```
    Value for the Content-Encoding header that indicates that DEFLATE encoding is in use.
    
    See Also:
    
    Constant Field Values
  - UTF_8
```
public static final java.nio.charset.Charset UTF_8
```
    UTF-8: eight-bit UCS Transformation Format.
  - ISO_8859_1
```
public static final java.nio.charset.Charset ISO_8859_1
```
    ISO-8859-1: ISO Latin Alphabet Number 1 (ISO-LATIN-1).
  - MAP_STRING_WILDCARD
```
public static final java.lang.reflect.Type MAP_STRING_WILDCARD
```
    Type literal for Map<String, ?>.
- Method Detail
  - checkArgument
```
public static void checkArgument(boolean expression,
                                 java.lang.String errorMessageTemplate,
                                 java.lang.Object... errorMessageArgs)
```
    Copy of com.google.common.base.Preconditions#checkArgument.
  - checkNotNull
```
public static <T> T checkNotNull(T reference,
                                 java.lang.String errorMessageTemplate,
                                 java.lang.Object... errorMessageArgs)
```
    Copy of com.google.common.base.Preconditions#checkNotNull.
  - checkState
```
public static void checkState(boolean expression,
                              java.lang.String errorMessageTemplate,
                              java.lang.Object... errorMessageArgs)
```
    Copy of com.google.common.base.Preconditions#checkState.
  - isDefault
```
public static boolean isDefault(java.lang.reflect.Method method)
```
    Identifies a method as a default instance method.
  - emptyToNull
```
public static java.lang.String emptyToNull(java.lang.String string)
```
    Adapted from com.google.common.base.Strings#emptyToNull.
  - toArray
```
public static <T> T[] toArray(java.lang.Iterable<? extends T> iterable,
                              java.lang.Class<T> type)
```
    Adapted from com.google.common.base.Strings#emptyToNull.
  - valuesOrEmpty
```
public static <T> java.util.Collection<T> valuesOrEmpty(java.util.Map<java.lang.String,java.util.Collection<T>> map,
                                                        java.lang.String key)
```
    Returns an unmodifiable collection which may be empty, but is never null.
  - ensureClosed
```
public static void ensureClosed(java.io.Closeable closeable)
```
  - resolveLastTypeParameter
```
public static java.lang.reflect.Type resolveLastTypeParameter(java.lang.reflect.Type genericContext,
                                                              java.lang.Class<?> supertype)
                                                       throws java.lang.IllegalStateException
```
    Resolves the last type parameter of the parameterized supertype, based on the genericContext, into its upper bounds.
    Implementation copied from retrofit.RestMethodInfo.
    
    Parameters:
    
    genericContext - Ex. Field.getGenericType()
    
    supertype - Ex. Decoder.class
    
    Returns:
    
    in the example above, the type parameter of Decoder.
    
    Throws:
    
    java.lang.IllegalStateException - if supertype cannot be resolved into a parameterized type using context.
  - emptyValueOf
```
public static java.lang.Object emptyValueOf(java.lang.reflect.Type type)
```
    This returns well known empty values for well-known java types. This returns null for types not in the following list.
    - [Bb]oolean
    - byte[]
    - Collection
    - Iterator
    - List
    - Map
    - Set
    When decoding HTTP 404 status, you'll need to teach decoders a default empty value for a type. This method cheaply supports typical types by only looking at the raw type (vs type hierarchy). Decorate for sophistication.
  - toString
```
public static java.lang.String toString(java.io.Reader reader)
                                 throws java.io.IOException
```
    Adapted from com.google.common.io.CharStreams.toString().
    
    Throws:
    
    java.io.IOException
  - toByteArray
```
public static byte[] toByteArray(java.io.InputStream in)
                          throws java.io.IOException
```
    Adapted from com.google.common.io.ByteStreams.toByteArray().
    
    Throws:
    
    java.io.IOException

Class Util

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

CONTENT_LENGTH

CONTENT_ENCODING

RETRY_AFTER

ENCODING_GZIP

ENCODING_DEFLATE

UTF_8

ISO_8859_1

MAP_STRING_WILDCARD

Method Detail

checkArgument

checkNotNull

checkState

isDefault

emptyToNull

toArray

valuesOrEmpty

ensureClosed

resolveLastTypeParameter

emptyValueOf

toString

toByteArray