Create a Java project by programming in eclipse

Steps:
1. Create an org. Eclipse. Core. Resources. iproject
2. Set description for the project, that is, generate the. project file.
Note: A. javacore. nature_id = "org. Eclipse. jdt. Core. javanature" indicates a Java project.
B. When you place description in a project, ensure that the project exists and is being opened.
3. Convert org. Eclipse. Core. Resources. iproject to a Java project.
Ijavaproject javaproject = javacore. Create (project );
4. Obtain the JRE path of eclipse and the path of the current project, and set the directory for storing source code and *. class files.
This part generates the content in the. classpath file.
5. Compile a string into a Java file and the corresponding. Class file.

Example:
Package org. wliu. sample. createnewjavaproject. actions;

Import java. util. arrays;
Import java. util. hashset;
Import java. util. Set;

Import org. Eclipse. Core. Resources. ifolder;
Import org. Eclipse. Core. Resources. iprojectdescription;
Import org. Eclipse. Core. Resources. iresource;
Import org. Eclipse. Core. Resources. iworkspaceroot;
Import org. Eclipse. Core. Resources. resourcesplugin;
Import org. Eclipse. Core. runtime. coreexception;
Import org. Eclipse. Core. runtime. nullprogressmonitor;
Import org. Eclipse. Core. runtime. path;
Import org. Eclipse. Core. runtime. subprogressmonitor;
Import org. Eclipse. jdt. Core. iclasspathentry;
Import org. Eclipse. jdt. Core. ijavaproject;
Import org. Eclipse. jdt. Core. ipackagefragment;
Import org. Eclipse. jdt. Core. ipackagefragmentroot;
Import org. Eclipse. jdt. Core. javacore;
Import org. Eclipse. jdt. Core. javamodelexception;
Import org. Eclipse. jdt. UI. preferenceconstants;
Import org. Eclipse. jface. Action. iaction;
Import org. Eclipse. jface. dialogs. messagedialog;
Import org. Eclipse. jface. Viewers. iselection;
Import org. Eclipse. UI. iworkbenchwindow;
Import org. Eclipse. UI. iworkbenchwindowactiondelegate;

/**
* Our sample action implements workbench action delegate.
* The Action proxy will be created by the workbench and
* Shown in the UI. When the user tries to use the action,
* This delegate will be created and execution will be
* Delegated to it.
* @ See iworkbenchwindowactiondelegate
*/
Public class sampleaction implements iworkbenchwindowactiondelegate {
Private iworkbenchwindow window;
/**
* The constructor.
*/
Public sampleaction (){
}

/**
* The action has been activated. The argument of
* Method represents the 'real' action sitting
* In the workbench UI.
* @ See iworkbenchwindowactiondelegate # Run
*/
Public void run (iaction action ){
Messagedialog. openinformation (
Window. getshell (),
"Createnewjavaproject plug-in ",
"Hello, eclipse world ");
// Create the resource project
Iworkspaceroot root = resourcesplugin. getworkspace (). getroot ();
Org. Eclipse. Core. Resources. iproject project = root. getproject ("wliu ");
Ijavaproject javaproject = NULL;
If (! Project. exists ()){
Iprojectdescription prjdesc = root. getworkspace (). newprojectdescription (project. getname ());
String [] oldnatureids = prjdesc. getnatureids ();
String [] newnatureids = new string [oldnatureids. Length + 1];
System. arraycopy (oldnatureids, 0, newnatureids, 0, oldnatureids. Length );
Newnatureids [oldnatureids. Length] = javacore. nature_id; // define this is a Java Project
Prjdesc. setnatureids (newnatureids );
Try {
Project. Create (New nullprogressmonitor ());
Project. Open (iresource. background_refresh, new subprogressmonitor (New nullprogressmonitor (), 1000 ));
Project. setdescription (prjdesc, new nullprogressmonitor ());
} Catch (coreexception e ){
// Todo auto-generated Catch Block
E. printstacktrace ();
}

} Else {
Try {
Iprojectdescription prjdesc = project. getdescription ();
String [] oldnatureids = prjdesc. getnatureids ();
String [] newnatureids = new string [oldnatureids. Length + 1];
System. arraycopy (oldnatureids, 0, newnatureids, 0, oldnatureids. Length );
Newnatureids [oldnatureids. Length] = javacore. nature_id; // define this is a Java Project
Prjdesc. setnatureids (newnatureids );
Project. Open (iresource. background_refresh, new subprogressmonitor (New nullprogressmonitor (), 1000 ));
Project. setdescription (prjdesc, new nullprogressmonitor ());
} Catch (coreexception e ){
E. printstacktrace ();

}
}
Javaproject = javacore. Create (project );
// Create the classpath entries

// Get the platform's JRE classpath
Iclasspathentry [] jreclasspaths = preferenceconstants. getdefaultjrelibrary ();
// Get the project existing classpath
Iclasspathentry [] oldclasspathentries = NULL;
Try {
Oldclasspathentries = javaproject. getrawclasspath ();
} Catch (javamodelexception e ){
// Todo auto-generated Catch Block
E. printstacktrace ();
}
Set <iclasspathentry> newclasspathentries = new hashset <iclasspathentry> ();
Newclasspathentries. addall (arrays. aslist (jreclasspaths ));
Newclasspathentries. addall (arrays. aslist (oldclasspathentries ));
// Try {
//
Javaproject. setrawclasspath (newclasspathentries. toarray (New
Iclasspathentry [newclasspathentries. Size ()]), new
Nullprogressmonitor ());
//} Catch (javamodelexception e ){
/// Todo auto-generated Catch Block
// E. printstacktrace ();
//}

// Create the output location
Ifolder binfolder = javaproject. getproject (). getfolder ("bin ");
Try {
If (! Binfolder. exists ()){
Binfolder. Create (true, true, new nullprogressmonitor ());
}
} Catch (coreexception e ){
// Todo auto-generated Catch Block
E. printstacktrace ();
}
Try {
Javaproject. setoutputlocation (binfolder. getfullpath (), new nullprogressmonitor ());
} Catch (javamodelexception e ){
// Todo auto-generated Catch Block
E. printstacktrace ();
}

// Create the source folder
Ifolder srcfolder = javaproject. getproject (). getfolder ("src ");
If (! Srcfolder. exists ()){
Try {
Srcfolder. Create (true, true, null );
} Catch (coreexception e ){
// Todo auto-generated Catch Block
E. printstacktrace ();
}
}

// Add the SRC classpath entry to the. classpath File
Iclasspathentry classpathentry = javacore. newsourceentry (srcfolder. getfullpath ());
Newclasspathentries. Add (classpathentry );
Iclasspathentry removeentry = javacore. newsourceentry (New Path ("/" + project. getname ()));
If (newclasspathentries. Contains (removeentry )){
Newclasspathentries. Remove (removeentry );
}
Try {
Javaproject. setrawclasspath (newclasspathentries. toarray (New
Iclasspathentry [newclasspathentries. Size ()]), new
Nullprogressmonitor ());
} Catch (javamodelexception e ){
// Todo auto-generated Catch Block
System. Err. println ("error ");
E. printstacktrace ();
}
System. Out. println ("OK ");

Try {
Ipackagefragmentroot fileroot = javaproject. findpackagefragmentroot (New Path ("/" + project. getname () + "/src "));

Ipackagefragment packagefragment = fileroot. createpackagefragment ("org. talend. sample", true, new nullprogressmonitor ());

String strjava = "package org. talend. sample; public class test {public static void main (string [] ARGs) {" +
"System. Out. println (/" OK /");}}";
Packagefragment. createcompilationunit ("test. Java", strjava, true, new nullprogressmonitor ());

} Catch (javamodelexception e ){

}

}

/**
* Selection in the workbench has been changed. We
* Can change the state of the 'real' action here
* If we want, but this can only happen after
* The delegate has been created.
* @ See iworkbenchwindowactiondelegate # selectionchanged
*/
Public void selectionchanged (iaction action, iselection selection ){
}

/**
* We can use this method to dispose of any system
* Resources we previusly allocated.
* @ See iworkbenchwindowactiondelegate # dispose
*/
Public void dispose (){
}

/**
* We will cache window object in order
* Be Able To provide parent shell for the message dialog.
* @ See iworkbenchwindowactiondelegate # init
*/
Public void Init (iworkbenchwindow window ){
This. Window = window;
}
}