AttrSettable ( Frame4J -- the Java framework de.frame4j... )

All Known Implementing Classes:

App, AskAlert, BlinkOnPi, Del, Era, FS, FuR, HelloFrame4J, MakeDigest, PKextr, SAXdemo, SendMail, SVNkeys, SVNkeysFilter, TestOnPi, UCopy, Update, XMLio
```
public interface AttrSettable
```
DynamicMBean - indirect implementation.

This interface just describes an indirect or helper implementation for (dynamic) MBean attribute setters. It may be used in initialisation and other places, where the direct usage of DynamicMBean (or its implementation) would be overkill.

Copyright 2009 Albrecht Weinert

Version:

"V.39" (17.04.2021")

Author:

A. Weinert

See Also:

PropMapHelper.setField(Object, String, String)

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`ILLEGAL_TYPE` Return value for `setAttribute()`.
`static int`	`ILLEGAL_VALUE` Return value for `setAttribute()`.
`static int`	`NO_ATTRIBUTE` Return value for `setAttribute()`.
`static int`	`NO_KNOWN_ATTRIBUTE` Return value for `setAttribute()`.
`static int`	`NO_VALUE` Return value for `setAttribute()`.
`static int`	`OK` Return value for `setAttribute()`.
`static String[]`	`retVtext` Mapping return values to text.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method and Description
`static String`	`retVtext(int ret)` Mapping return values to text.
`int`	`setAttribute(String name, Object value)` Set a named attribute or property.

- Field Detail
  - OK
```
static final int OK
```
    Return value for setAttribute().
    
    OK: attribute was set to the value specified.
    
    See Also:
    
    Constant Field Values
  - NO_ATTRIBUTE
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static final int NO_ATTRIBUTE
```
    Return value for setAttribute().
    
    No attribute was specified.
    
    See Also:
    
    Constant Field Values
  - NO_VALUE
```
static final int NO_VALUE
```
    Return value for setAttribute().
    
    No value was specified and null is illegal as value.
    This case may also be signalled by ILLEGAL_TYPE or by ILLEGAL_VALUE.
    
    See Also:
    
    Constant Field Values
  - ILLEGAL_TYPE
```
static final int ILLEGAL_TYPE
```
    Return value for setAttribute().
    
    The type of the value specified, cannot be used. This should scarcely happen (by contract of setAttribute(String, Object)) if the value parameter is a character sequence.
    
    See Also:
    
    Constant Field Values
  - ILLEGAL_VALUE
```
static final int ILLEGAL_VALUE
```
    Return value for setAttribute().
    
    The value specified is illegal for that attribute. This may also be returned if a setter which setAttribute(String, Object) delegates to throws an exception.
    
    See Also:
    
    Constant Field Values
  - NO_KNOWN_ATTRIBUTE
```
static final int NO_KNOWN_ATTRIBUTE
```
    Return value for setAttribute().
    
    The attribute specified is not known / implemented in method called.
    
    See Also:
    
    Constant Field Values
  - retVtext
```
static final String[] retVtext
```
    Mapping return values to text.
- Method Detail
  - retVtext
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static String retVtext(int ret)
```
    Mapping return values to text.
    
    This method is for debugging.
  - setAttribute
```
int setAttribute(String name,
                 Object value)
```
    Set a named attribute or property.
    
    This method implements the settings of a (sub) set of properties. The implementation may be used do do the real work in for in a DynamicMBean's implementation attribute setters.
    
    The preferred type for value is CharSequence or derived. It is most strongly recommended that the type String is always accepted for any settable attribute / property.
    
    The value NO_KNOWN_ATTRIBUTE is returned, if name and value are given (non null / empty), but this method just knows nothing about a property name. This (plus perhaps NO_VALUE if other setters might accept null) is the only return value where further delegation to other setters makes any sense.
    
    Hint 1 for implementation (w/o delegation):
```
  @Override public int setAttribute(final String name, final Object value){
     if (name == null || name.isEmpty()) return NO_ATTRIBUTE;
     final boolean isNull = value == null;
     final Class<? extends Object>  cl = isNull ? null : value.getClass();
     final boolean isStringVal = !isNull && cl == java.lang.String.class;
     // do own job; return 0 (OK) on set attribute
     // return failure on implemented attributes, but wrong value or type            
     return NO_KNOWN_ATTRIBUTE; // not implemented here (try other setters)
  } // setAttribute(String, Object)
  
```
    Hint 2 for implementation (with prior delegation to like above):
```
  @SuppressWarnings("null")
  @Override public int setAttribute(final String name, final Object value) {
     final int ret = super.setAttribute(name, value); // (1)
     if (ret != NO_KNOWN_ATTRIBUTE) return ret; // all done by (1) 
     final boolean isNull = value == null;
     final Class<? extends Object>  cl = isNull ? null : value.getClass();
     final boolean isStringVal = !isNull && cl == java.lang.String.class;
     /// rest as above
  
```
    Parameters:
    
    name - the name of the property to be set; null, empty and start with < 'a' will be rejected with NO_ATTRIBUTE
    
    value - the new value for the named property
    depending on the implementation and the named property any object state and type including null might be accepted (with OK) or rejected (with NO_VALUE, ILLEGAL_TYPE or ILLEGAL_VALUE)
    
    Returns:
    
    0 = OK, NO_ATTRIBUTE, NO_KNOWN_ATTRIBUTE, NO_VALUE, ILLEGAL_TYPE or ILLEGAL_VALUE

Interface AttrSettable

Field Summary

Method Summary

Field Detail

OK

NO_ATTRIBUTE

NO_VALUE

ILLEGAL_TYPE

ILLEGAL_VALUE

NO_KNOWN_ATTRIBUTE

retVtext

Method Detail

retVtext

setAttribute