/**
* If there's an operator and filename in the list of parameters, then if operator is '>',
* overwrites the contents of outFile with the string text; if the operator is '>>', appends text
* to the contents of outFile; If outFile doesn't exist, creates a new file outFile and appends
* text to its contents.
*
* @param params A list of parameters which must include a string and may optionally include an
* operator and a filename.
*/
public String echo(List<String> params) throws Exception {
// The content to be output in retrieved
String content = getContent(params);
// The last index of the string, if it exists, in the List params.
int last_index = getLastIndex(params);
// If content is a valid string and the correct syntax is used to write
// to a file, then this code is executed.
if (params.size() > last_index + 2
&& content.startsWith("\"")
&& content.endsWith("\"")
&& content.startsWith("\"")
&& params.get(last_index + 1).startsWith(">")) {
// The file name and parameter for writing is retrieved.
String file_name = params.get(last_index + 2);
String param = params.get(last_index + 1);
// The quotations are striped from the string to be used.
content = content.substring(1, content.length() - 1);
// The file is retrieved if it exists.
JShellItem targetFile = getItemAtPath(file_name, 0);
// The file is deleted if it exists and is to be overwritten.
// Otherwise the file is created.
if (!(param.equals(">>") & targetFile != null)) {
if (targetFile != null) {
targetFile.getParentDirectory().removeItem(targetFile);
}
mkfile(file_name);
targetFile = getItemAtPath(file_name, 0);
}
// The file's contents are appended to either a blank (new) file
// or an old file, depending on the user's input.
((File) targetFile).setContent(((File) targetFile).getContent() + content);
return "";
// If the string is valid but the syntax is incorrect, then this
// code is
// executed.
} else if (content.endsWith("\"") & content.startsWith("\"")) {
if (content.substring(1, content.length() - 1).isEmpty()) {
return content.substring(1, content.length() - 1);
}
return content.substring(1, content.length() - 1) + "\n";
// If the string is not valid, this code is executed.
} else {
return "Echo requires a string with \" & \" surrounding the words" + "\n";
}
}
