将在jdk1.4中编译的应用程序转换为jdk1.7

Question

I'm working on an application that has been created long time ago (maybe 2008/2009). Now I got the task of upgrading the server. Previously it was compiled in jdk1.4. Now I have to make the application compatible with jdk1.7. I tried to compile it with jre7 and I've changed source and target value of ant build.xml file to 1.7 . And also in ANT build the jre7 is selected as compiler environment. I'm getting the following error message:

 [javac] javac: invalid target release: 1.7
    [javac] Usage: javac <options> <source files>
    [javac] where possible options include:
    [javac]   -g                        Generate all debugging info
    [javac]   -g:none                   Generate no debugging info
    [javac]   -g:{lines,vars,source}    Generate only some debugging info
    [javac]   -nowarn                   Generate no warnings
    [javac]   -verbose                  Output messages about what the compiler is doing
    [javac]   -deprecation              Output source locations where deprecated APIs are used
    [javac]   -classpath <path>         Specify where to find user class files
    [javac]   -sourcepath <path>        Specify where to find input source files
    [javac]   -bootclasspath <path>     Override location of bootstrap class files
    [javac]   -extdirs <dirs>           Override location of installed extensions
    [javac]   -d <directory>            Specify where to place generated class files
    [javac]   -encoding <encoding>      Specify character encoding used by source files
    [javac]   -source <release>         Provide source compatibility with specified release
    [javac]   -target <release>         Generate class files for specific VM version
    [javac]   -help                     Print a synopsis of standard options

I tried to print the java version using following line:

and it shows :

[echo] Using Java version 1.7.

What (other) changes do I need to make to make it work with jdk1.7?

Answer 1

Problem Solved. I was trying to compile with JRE7 instead of jdk1.7. with jdk1.7 installed and target and source changed in ant build.xml file solved my problem.