java - Controlling when object is created -

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suppose need create object follows , set values

    filemetadata filemeta = filecontainer.getmetadata();      filemeta.setfilename("file name");     filemeta.setserver("my box");     filemeta.setdirectory("/path/to/dir");     filemeta.setfiletype(filetype.properties);

i later intend use object reference useful.

i'd recognize fact possible user of system not set fields, instance, 1 may forget 

    filemeta.setdatemodified(12345);

is somehow possible guarantee (or specific) fields set before making object available?

there nothing in language enforce (except having lone visible constructor takes required parameters), can idiomatically, variation on builder pattern , method chaining:

filemetadata filemeta = new filemetadatabuilder(filecontainer.getmetadata())     .setfilename("file name")     .setserver("my box")     .setdirectory("/path/to/dir")     .setfiletype(filetype.properties)     .build();

the build() method can ensure required fields set before calling appropriate constructor of filemetadata required parameters.


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