I need to have a cross-platform newline reference to parse files, and I'm trying to find a way to do the equivalent of the usual
System.getProperty("line.separator");
but trying that in J2ME, I get a null String returned, so I'm guessing line.separator isn't included here. Are there any other direct ways to get a universal newline sequence in J2ME as string?
edit: clarified question a bit
Seems like I forgot to answer my question. I used a piece of code that allowed me to use "\r\n" as delimiter and actually considered \r and \n as well seperately:
public class Tokenizer {
public static String[] tokenize(String str, String delimiter) {
StringBuffer strtok = new StringBuffer();
Vector buftok = new Vector();
char[] ch = str.toCharArray(); //convert to char array
for (int i = 0; i < ch.length; i++) {
if (delimiter.indexOf(ch[i]) != -1) { //if i-th character is a delimiter
if (strtok.length() > 0) {
buftok.addElement(strtok.toString());
strtok.setLength(0);
}
}
else {
strtok.append(ch[i]);
}
}
if (strtok.length() > 0) {
buftok.addElement(strtok.toString());
}
String[] splitArray = new String[buftok.size()];
for (int i=0; i < splitArray.length; i++) {
splitArray[i] = (String)buftok.elementAt(i);
}
buftok = null;
return splitArray;
}
}
I don't think "line.separator" is a system property of JME. Take a look at this documentation at SDN FAQ for MIDP developers: What are the defined J2ME system property names?
Why do you need to get the line separator anyway? What I know is that you can use "\n" in JME.
Related
I have a String, and I would like to reverse it. For example, I am writing an AngularDart filter that reverses a string. It's just for demonstration purposes, but it made me wonder how I would reverse a string.
Example:
Hello, world
should turn into:
dlrow ,olleH
I should also consider strings with Unicode characters. For example: 'Ame\u{301}lie'
What's an easy way to reverse a string, even if it has?
The question is not well defined. Reversing arbitrary strings does not make sense and will lead to broken output. The first (surmountable) obstacle is Utf-16. Dart strings are encoded as Utf-16 and reversing just the code-units leads to invalid strings:
var input = "Music \u{1d11e} for the win"; // Music 𝄞 for the win
print(input.split('').reversed.join()); // niw eht rof
The split function explicitly warns against this problem (with an example):
Splitting with an empty string pattern ('') splits at UTF-16 code unit boundaries and not at rune boundaries[.]
There is an easy fix for this: instead of reversing the individual code-units one can reverse the runes:
var input = "Music \u{1d11e} for the win"; // Music 𝄞 for the win
print(new String.fromCharCodes(input.runes.toList().reversed)); // niw eht rof 𝄞 cisuM
But that's not all. Runes, too, can have a specific order. This second obstacle is much harder to solve. A simple example:
var input = 'Ame\u{301}lie'; // Amélie
print(new String.fromCharCodes(input.runes.toList().reversed)); // eiĺemA
Note that the accent is on the wrong character.
There are probably other languages that are even more sensitive to the order of individual runes.
If the input has severe restrictions (for example being Ascii, or Iso Latin 1) then reversing strings is technically possible. However, I haven't yet seen a single use-case where this operation made sense.
Using this question as example for showing that strings have List-like operations is not a good idea, either. Except for few use-cases, strings have to be treated with respect to a specific language, and with highly complex methods that have language-specific knowledge.
In particular native English speakers have to pay attention: strings can rarely be handled as if they were lists of single characters. In almost every other language this will lead to buggy programs. (And don't get me started on toLowerCase and toUpperCase ...).
Here's one way to reverse an ASCII String in Dart:
input.split('').reversed.join('');
split the string on every character, creating an List
generate an iterator that reverses a list
join the list (creating a new string)
Note: this is not necessarily the fastest way to reverse a string. See other answers for alternatives.
Note: this does not properly handle all unicode strings.
I've made a small benchmark for a few different alternatives:
String reverse0(String s) {
return s.split('').reversed.join('');
}
String reverse1(String s) {
var sb = new StringBuffer();
for(var i = s.length - 1; i >= 0; --i) {
sb.write(s[i]);
}
return sb.toString();
}
String reverse2(String s) {
return new String.fromCharCodes(s.codeUnits.reversed);
}
String reverse3(String s) {
var sb = new StringBuffer();
for(var i = s.length - 1; i >= 0; --i) {
sb.writeCharCode(s.codeUnitAt(i));
}
return sb.toString();
}
String reverse4(String s) {
var sb = new StringBuffer();
var i = s.length - 1;
while (i >= 3) {
sb.writeCharCode(s.codeUnitAt(i-0));
sb.writeCharCode(s.codeUnitAt(i-1));
sb.writeCharCode(s.codeUnitAt(i-2));
sb.writeCharCode(s.codeUnitAt(i-3));
i -= 4;
}
while (i >= 0) {
sb.writeCharCode(s.codeUnitAt(i));
i -= 1;
}
return sb.toString();
}
String reverse5(String s) {
var length = s.length;
var charCodes = new List(length);
for(var index = 0; index < length; index++) {
charCodes[index] = s.codeUnitAt(length - index - 1);
}
return new String.fromCharCodes(charCodes);
}
main() {
var s = "Lorem Ipsum is simply dummy text of the printing and typesetting industry.";
time('reverse0', () => reverse0(s));
time('reverse1', () => reverse1(s));
time('reverse2', () => reverse2(s));
time('reverse3', () => reverse3(s));
time('reverse4', () => reverse4(s));
time('reverse5', () => reverse5(s));
}
Here is the result:
reverse0: => 331,394 ops/sec (3 us) stdev(0.01363)
reverse1: => 346,822 ops/sec (3 us) stdev(0.00885)
reverse2: => 490,821 ops/sec (2 us) stdev(0.0338)
reverse3: => 873,636 ops/sec (1 us) stdev(0.03972)
reverse4: => 893,953 ops/sec (1 us) stdev(0.04089)
reverse5: => 2,624,282 ops/sec (0 us) stdev(0.11828)
Try this function
String reverse(String s) {
var chars = s.splitChars();
var len = s.length - 1;
var i = 0;
while (i < len) {
var tmp = chars[i];
chars[i] = chars[len];
chars[len] = tmp;
i++;
len--;
}
return Strings.concatAll(chars);
}
void main() {
var s = "Hello , world";
print(s);
print(reverse(s));
}
(or)
String reverse(String s) {
StringBuffer sb=new StringBuffer();
for(int i=s.length-1;i>=0;i--) {
sb.add(s[i]);
}
return sb.toString();
}
main() {
print(reverse('Hello , world'));
}
The library More Dart contains a light-weight wrapper around strings that makes them behave like an immutable list of characters:
import 'package:more/iterable.dart';
void main() {
print(string('Hello World').reversed.join());
}
There is a utils package that covers this function. It has some more nice methods for operation on strings.
Install it with :
dependencies:
basic_utils: ^1.2.0
Usage :
String reversed = StringUtils.reverse("helloworld");
Github:
https://github.com/Ephenodrom/Dart-Basic-Utils
Here is a function you can use to reverse strings. It takes an string as input and will use a dart package called Characters to extract characters from the given string. Then we can reverse them and join again to make the reversed string.
String reverse(String string) {
if (string.length < 2) {
return string;
}
final characters = Characters(string);
return characters.toList().reversed.join();
}
Create this extension:
extension Ex on String {
String get reverse => split('').reversed.join();
}
Usage:
void main() {
String string = 'Hello World';
print(string.reverse); // dlroW olleH
}
Reversing "Hello World"
I want to take pinyin (english) as an input and return Chinese characters that user can choose from. I saw that this has been implemented in many place (support by OS keyboards and various websites), but can't find a library to do it.
Or possibly even doing it myself if it's not that complex or require large amount of data.
The simplest way to do this is use javachinesepinyin, a lightweight Chinese Pinyin Input Method.
You can find related code here.
private String[] pinyinToWord(String[] o) {
Result ret = null;
try {
ret = ptw.labelStateOfNodes(Arrays.asList(o));
} catch (Exception ex) {
System.out.println(ex.getMessage());
}
Map<Double, String> results = new HashMap<Double, String>();
if (null != ret && ret.states() != null) {
for (int pos = 0; pos < ret.states()[o.length - 1].length; pos++) {
StringBuilder sb = new StringBuilder();
int[] statePath = Viterbi.getStatePath(ret.states(), ret.psai(), o.length - 1, o.length, pos);
for (int state : statePath) {
Character name = ptw.getStateBy(state);
sb.append(name).append(" ");
}
results.put(ret.delta()[o.length - 1][pos], sb.toString());
}
List<Double> list = new ArrayList<Double>(results.keySet());
Collections.sort(list);
Collections.reverse(list);
return results.get(list.get(0)).trim().split(" ");
}
return null;
}
Intro Slides in English: http://docs.google.com/present/edit?id=0AbbbdNFzwcADZGR3Z3N0NG1fMTk4M2hraGZjNmRw&hl=en
Live Demo: http://951438.appspot.com/pinyin.jsp?txt=zhongwenpinyinshurufa
If advanced features are needed, maybe you should consider use Rime Input Method Engine or sunpinyin.
FYI, Python Binding for sunpinyin.
After compiling an ArrayList in java, how do I print it as a string?
Using ArrayList.toString() gives the values with brackets around them and commas between them.
I want to print them without brackets and only spaces between them.
(Assuming Java)
You can write your own method to do that:
public static <T> String listToString(List<T> list) {
StringBuilder sb = new StringBuilder();
boolean b = false;
for (T o : list) {
if (b)
sb.append(' ');
sb.append(o);
b = true;
}
return sb.toString();
}
Or, if you're using Guava, you can use Joiner:
Joiner.on(' ').join(list)
Similarly, if you just are interested in printing, you can avoid creating a new string all together:
public static <T> void printList(List<T> list) {
for (T o : list) {
System.out.print(o);
System.out.print(' ');
}
System.out.println();
}
If you're using Eclipse Collections, you can use the makeString() method.
ArrayList<String> list = new ArrayList<String>();
list.add("one");
list.add("two");
list.add("three");
Assert.assertEquals(
"one two three",
ArrayListAdapter.adapt(list).makeString(" "));
If you can convert your ArrayList to a FastList, you can get rid of the adapter.
Assert.assertEquals(
"one two three",
FastList.newListWith("one", "two", "three").makeString(" "));
Note: I am a committer for Eclipse collections.
for c#
string.Join(" ", _list);
Not sure what language you're using, but try either:
ArrayList.join()
or
ArrayList.toArray().join()
for(int i = 0; i < arraylist.size(); i++){
System.out.print(arraylist.get(i).toString + " ");
}
???
I want to get the highest available string value in java how can i achieve this.
Example: hello jameswangfron
I want to get the highest string "jameswangfron"
String Text = request.getParameter("hello jameswangfron");
Please code example.
public class HelloWorld{
public static void main(String []args){
String text = "hello jameswangfron";
String[] textArray = text.split(" ");
String biggestString = "";
for(int i=0; i<textArray.length; i++){
if(i==0) {
textArray[i].length();
biggestString = textArray[i];
} else {
if(textArray[i].length()>textArray[i-1].length()){
biggestString = textArray[i];
}
}
}
System.out.println("Biggest String : "+biggestString);
}
}
And it shows the output as
Biggest String : jameswangfron
Maybe this will be easyer to understand
public class HelloWorld {
public static void main(String[] args) {
System.out.println(StringManipulator.getMaxLengthString("hello jameswangfron", " "));
}
}
class StringManipulator{
public static String getMaxLengthString(String data, String separator){
String[] stringArray = data.split(separator);
String toReturn = "";
int maxLengthSoFar = 0;
for (String string : stringArray) {
if(string.length()>maxLengthSoFar){
maxLengthSoFar = string.length();
toReturn = string;
}
}
return toReturn;
}
}
But there is a catch. If you pay attention to split method from class String, you will find out that the spliter is actually a regex. For your code, i see that you want to separate the words (which means blank space). if you want an entire text to search, you have to pass a regex.
Here's a tip. If you want your words to be separated by " ", ".", "," (you get the ideea) then you should replace the " " from getMaxLengthString method with the following
"[^a-zA-Z0-9]"
If you want digits to split up words, simply put
"[^a-zA-Z]"
This tells us that we use the separators as anything that is NOT a lower case letter or upper case letter. (the ^ character means you don't want the characters you listed in your brackets [])
Here is another way of doing this
"[^\\w]"
\w it actually means word characters. so if you negate this (with ^) you should be fine
So far I've only written console applications. My first application using MFC (in Visual Studio 2010) is basically a form with two multiline boxes (using String[] arrays noted with String^) and a button to activate text processing. It should search the String^ for a [, look for the ] behind it and delete all characters between them (including the []). With 'normal' C++ strings, this isn't difficult. String^ however is more like an object and MSDN tells me to make use of the Remove method. So, I tried to implement it.
public ref class Form1 : public System::Windows::Forms::Form
{
public:
Form1(void)
{
InitializeComponent();
//
//TODO: Add the constructor code here
//
}
String^ DestroyCoords(String^ phrase)
{
int CoordsStart = 0;
int CoordsEnd = 0;
int CharCount = 0;
for each (Char ch in phrase)
{
if (ch == '[')
CoordsStart = CharCount;
if (ch == ']')
{
CoordsEnd = CharCount;
//CoordsEnd = phrase->IndexOf(ch);
phrase->Remove( CoordsStart , CoordsEnd-CoordsStart );
}
CharCount++;
}
return phrase;
}
The button using the method:
private: System::Void button1_Click(System::Object^ sender, System::EventArgs^ e) {
TempString = String::Copy(BoxInput->Text);
DestroyCoords(TempString);
BoxOutput->Text = TempString;
The function seems to hit the correct places at the correct time, but the phrase->Remove() method is doing absolutely nothing..
I'm no OO hero (as said, I normally only build console applications), so it's probably a rookie mistake. What am I doing wrong?
In C++/CLI, System::String is immutable, so Remove creates a new String^. This means you'll need to assign the results:
phrase = phrase->Remove( CoordsStart , CoordsEnd-CoordsStart );
The same is true in your usage:
TempString = DestroyCoords(TempString);
BoxOutput->Text = TempString;
Note that this will still not work, as you'd need to iterate through your string in reverse (as the index will be wrong after the first removal).
No MFC here, that's the C++/CLI that Microsoft uses for writing .NET programs in C++.
The .NET System::String class is immutable, so any operations you expect to modify the string actually return a new string with the adjustment made.
A further problem is that you're trying to modify a container (the string) while iterating through it. Instead of using Remove, have a StringBuilder variable and copy across the parts of the string you want to keep. This means only a single copy and will be far faster than repeated calls to Remove each of which makes a copy. And it won't interfere with iteration.
Here's the right approach:
int BracketDepth = 0;
StringBuilder sb(phrase->Length); // using stack semantics
// preallocated to size of input string
for each (Char ch in phrase)
{
if (ch == '[') { // now we're handling nested brackets
++BracketDepth;
}
else if (ch == ']') { // and complaining if there are too many closing brackets
if (!BracketDepth--) throw gcnew Exception();
}
else if (!BracketDepth) { // keep what's not brackets or inside brackets
sb.Append(ch);
}
}
if (BracketDepth) throw gcnew Exception(); // not enough closing brackets
return sb.ToString();