Eclipse AST not changing files which are not opened in eclipse - eclipse-plugin

Question

I am trying to modify source code using eclipse plugin, JDT and AST (Abstract Syntax Tree). I can read all Java files and make operation on all those file, But when i am saving those changes (Edits) in to files using
TextEdit edits = rewriter.rewriteAST();
// apply the text edits to the compilation unit
edits.apply(document);
iCompilationUnit.getBuffer().setContents(document.get());
It only make changes in file those are open in eclipse in unsaved mode. Rest of files are not affected.
Find my code snippet below:
CompilationUnit cu = parse(iCompilationUnit);
MethodVisitor visitor = new MethodVisitor();
cu.accept(visitor);
String source = iCompilationUnit.getSource();
Document document= new Document(source);
ASTRewrite rewriter = ASTRewrite.create(cu.getAST());
cu.recordModifications();
for (MethodDeclaration methodDeclaration : visitor.getMethods()) {
System.out.print("Method name: " + methodDeclaration.getName()
+ " Return type: " + methodDeclaration.getReturnType2());
MethodDeclaration methodDecl = methodDeclaration;
Block block = methodDecl.getBody();
ListRewrite listRewrite = rewriter.getListRewrite(block, Block.STATEMENTS_PROPERTY);
Statement placeHolder = (Statement) rewriter.createStringPlaceholder("System.out.println(\"Test Print\");", ASTNode.EMPTY_STATEMENT);
listRewrite.insertFirst(placeHolder, null);
}
TextEdit edits = rewriter.rewriteAST();
// apply the text edits to the compilation unit
edits.apply(document);
iCompilationUnit.getBuffer().setContents(document.get());

Answer 1

Try to:
Apply the TextEdit directly to the ICompilationUnit instead of using Document.
Use ICompilationUnit.commitWorkingCopy to save the changes
I use code similar to this:
iCompilationUnit.becomeWorkingCopy(new NullProgressMonitor());
CompilationUnit cu = parse(iCompilationUnit);
ASTRewrite rewriter = ASTRewrite.create(cu.getAST());
... process AST ...
iCompilationUnit.applyTextEdit(rewrite.rewriteAST(), new NullProgressMonitor());
iCompilationUnit.commitWorkingCopy(false, new NullProgressMonitor());