private JExpression convertString(JExpression expr) {
JPrimitiveType charType = program.getTypePrimitiveChar();
if (expr.getType() == charType) {
if (expr instanceof JCharLiteral) {
JCharLiteral charLit = (JCharLiteral) expr;
return program.getLiteralString(new char[] {charLit.getValue()});
} else {
// Replace with Cast.charToString(c)
JMethodCall call = new JMethodCall(program, expr.getSourceInfo(),
null, program.getIndexedMethod("Cast.charToString"));
call.getArgs().add(expr);