Imposta il livello di conformità del compilatore Java

Question

Ho bisogno di compilare un programma Java sulla riga di comando e sto cercando di impostare il livello del compilatore su uno inferiore (1.6). Ho provato come questo, ma non ha funzionato:

javac -1.6 Hello.java 

Answer 1

Usa -source e -target opzioni:

javac -target 1.6 -source 1.6 Hello.java 

Answer 2

Usa: javac -source 1.6 -target 1.6 Hello.java

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Queste informazioni provengono da corsa javac -help:

Usage: javac <options> <source files> 
where possible options include: 
    -g       Generate all debugging info 
    -g:none     Generate no debugging info 
    -g:{lines,vars,source}  Generate only some debugging info 
    -nowarn     Generate no warnings 
    -verbose     Output messages about what the compiler is doing 
    -deprecation    Output source locations where deprecated APIs are used 
    -classpath <path>   Specify where to find user class files and annotation processors 
    -cp <path>     Specify where to find user class files and annotation processors 
    -sourcepath <path>   Specify where to find input source files 
    -bootclasspath <path>  Override location of bootstrap class files 
    -extdirs <dirs>   Override location of installed extensions 
    -endorseddirs <dirs>  Override location of endorsed standards path 
    -proc:{none,only}   Control whether annotation processing and/or compilation is done. 
    -processor <class1>[,<class2>,<class3>...]Names of the annotation processors to run; bypasses default discovery process 
    -processorpath <path>  Specify where to find annotation processors 
    -d <directory>    Specify where to place generated class files 
    -s <directory>    Specify where to place generated source files 
    -implicit:{none,class}  Specify whether or not to generate class files for implicitly referenced files 
    -encoding <encoding>  Specify character encoding used by source files 
    -source <release>   Provide source compatibility with specified release 
    -target <release>   Generate class files for specific VM version 
    -version     Version information 
    -help      Print a synopsis of standard options 
    -Akey[=value]    Options to pass to annotation processors 
    -X       Print a synopsis of nonstandard options 
    -J<flag>     Pass <flag> directly to the runtime system 

Answer 3

Java doc dice, (ricerca di opzioni di compilazione trasversali)

By default, classes are compiled against the bootstrap and extension classes of theplatform that javac shipped with. But javac also supports cross-compiling, where classesare compiled against a bootstrap and extension classes of a different Java platformimplementation. It is important to use -bootclasspath and -extdirs when cross-compiling;see Cross-Compilation Example below.

-target version 

generare file di classe che l'obiettivo di una versione specifica della VM. I file di classe verranno eseguiti sulla destinazione specificata e nelle versioni successive, ma non sulle versioni precedenti della VM. Gli obiettivi validi sono 1.1, 1.2, 1.3, 1.4, 1.5 (anche 5), 1.6 (anche 6) e 1.7 (anche 7). L'impostazione predefinita per -target dipende dal valore di -source:

If -source is not specified, the value of -target is 1.7 
If -source is 1.2, the value of -target is 1.4 
If -source is 1.3, the value of -target is 1.4 
If -source is 1.5, the value of -target is 1.7 
If -source is 1.6, the value of -target is 1.7 
For all other values of -source, the value of -target is the value of -source. 

Quindi,

javac -target 1.6 -source 1.6 yourJavaProgram.java 

Answer 4

Usa sotto il comando:

javac -target 1.6 -source 1.6 Hello.java