I am using the split() function to fill an array and I am trying to enter each element into a Mysql table. What is the best way to do this? How can I make the loop iterate until it reaches the end of the array? I was thinking I might need a scanner object that reads from the array which would allow me to use the .hasNext() function. Is there a better way than this?
String text = "This is my example text string";
String array[] = text.split(" ");
Thanks
First of all, text.split(" ") returns String[] not String, but you can loop through the array like this:
String text = "This is my example text string";
String[] array = text.split(" ");
for (String item : array) {
// do something with each item
// like build an SQL statement
}
Related
I have a string which is :
1|name|lastname|email|tel \n
2|name|lastname|email|tel \n
I know that I have to use a loop to display all lines but the problem is that in my assignment
I can't use arrays or other classes than String and System.
Also I would like to sort names by ascending order without using sort method or arrays.
Do I have to use compareTo method to compare two names ?
If that's the case, how do I use compareTo method to sort names.
For example, if compareTo returns 1, that means that the name is greater than the other one. In that case how do I manage the return to sort name properly in the string ?
To display all substrings of the string as in the example, you can just go through all characters one by one and store them in a string. Whenever you hit a delimiter (e.g. | or \n), print the last string.
Here's a thread on iterating through characters of a string in Java:
What is the easiest/best/most correct way to iterate through the characters of a string in Java?
If you also need to sort the names in ascending order without an array, you will need to scan the input many times - sorting N strings takes at least N*log(N) steps. If this is a data structure question, PriorityQueue should do the trick for you - insert all substrings and then pop them out in a sorted fashion :)
building on the previous answer by StoneyKeys, since i do not have the privilege to comment, you can use a simple if statement that when the char is a delimiter, System.out.println() your previous scanned string. Then you can reset the string to an empty string in preparation for scanning the next string.
In java, there are special .equals() operators for strings and chars so when you won't be using == to check strings or char. Do look into that. To reset the value of string just assign it a new value. This is because the original variable points at a certain string ie "YHStan", by making it point at "", we are effectively "resetting" the string. ie scannedstr = "";
Please read the code and understand what each line of code does. The sample code and comments is only for your understanding, not a complete solution.
String str ="";
String value = "YH\nStan";
for (int i=0; i <value.length(); i++) {
char c = value.charAt(i);
String strc = Character.toString(c);
//check if its a delimiter, using a string or char .equals(), if it is print it out and reset the string
if (strc.equals("\n")) {
System.out.println(str);
str ="";
continue; // go to next iteration (you can instead use a else if to replace this)
}
//if its not delimiter append to str
str = str +strc;
//this is to show you how the str is changing as we go through the loop.
System.out.println(str);
}
System.out.println(str); //print out final string result
This gives a result of:
Y
YH
YH
S
St
Sta
Stan
Stan
Currently, I have trouble attempting to print out the individual lengths efficiently.
String[] array = {"test", "testing", "tests"};
int arraylength = array[0].length();
System.out.println(arraylength);
Now, this does work in printing out the length however, it is inefficient and doesn't work if theoretically I don't know the length of the array.
Thanks for your input and I would appreciate if the code insisted contains "System.out.println" included so I don't have trouble figuring out which to print out.
Use this:
String[] array = {"test", "testing", "tests"};
for(String str : array) {
System.out.println(str.length());
}
If you are using Java 8 then it's a one liner :)
Arrays.asList(array).forEach(element -> System.out.println(element.length()));
What you are doing is, converting your array to a list and then running a for loop over it. Then for every element, you are printing out the length of the element.
EDIT
From one of the comment, this is even a better version of my code.
Arrays.stream(array).map(String::length).forEach(System.out::println);
Here first you convert your array to a list and then map each element to the function length of string class, then you run a foreach over it which prints out the mapped values.
String[] array = {"test", "testing", "tests"};
The length for array is:
int arraylength = array.length;
To have retrieve length for string:
for(String string: array) {
System.out.println(string.length());
}
Take user input for 5 times, store them in a variable and display all 5 values in last. How can I do this in Java? Without using arrays, collections or database. Only single variable like String and int.
Output should look like this
https://drive.google.com/file/d/0B1OL94dWwAF4cDVyWG91SVZjRk0/view?pli=1
This seems like a needless exercise in futility, but I digress...
If you want to store them in a single string, you can do it like so:
Scanner in = new Scanner(System.in);
String storageString = "";
while(in.hasNext()){
storageString += in.next() + ";";
}
if you then input foo bar baz storageString will contain foo;bar;baz;. (in.next() will read the input strings to the spaces, and in.hasNext() returns false at the end of the line)
As more strings are input, they are appended to the storageString variable. To retrieve the strings, you can use String.split(String regex). Using this is done like so:
String[] strings = storageString.split(";");
the strings array which is retrieved here from the storageString variable above should have the value ["foo", "bar", "baz"].
I hope this helps. Using a string as storage is not optimal because JVM creates a new object every time a string is appended onto it. To get around this, use StringBuilder.
*EDIT: I originally had said the value of the strings array would be ["foo", "bar", "baz", ""]. This is wrong. The javadoc states 'Trailing empty strings are therefore not included in the resulting array'.
public static void main(String[] args) {
String s = "";
Scanner in = new Scanner(System.in);
for(int i=0;i<5;i++){
s += in.nextLine();
}
System.out.println(s);
}
Why dont you use Stingbuilder or StringBuffer, keep appending the some delimiter followed by the input text.
Use simple String object and concatenate it with new value provided by user.
String myString = "";
// while reading from input
myString += providedValue;
I currently am running a for loop which reads a List object and then splits them into arrays. Here is the sample code:
List<String> lines = Arrays.asList("foo,foo,foo","bar,baz,foo","foo,baz,foo", "baz,baz,baz", "zab,baz,zab");
for (String line : lines){
String[] array = line.split(",");
String[] arraySplit2 = array[0].split(",");
System.out.print(Arrays.toString(arraySplit2));
}
The output is:
[foo][bar][foo][baz][zab]
I wish to concatenate the array strings into a single one under the loop so that it displays:
[foo, bar, foo, baz, zab]
I'm having a bit of trouble because the conditions of the loop prevent me from doing the increase int i trick and using System.arraycopy(). I'm open to ideas such as changing the structure of the loop itself.
You seem to be trying to create an array out of first items from each line.
First, So you need to create the result array first with the size of number of lines:
String[] result = new String[lines.size()];
int index = 0;
You do not need the second split, in the for loop populate the result array:
result[index++] = array[0]
After the loop print your result array.
Not 100% sure on what you want, but I guess something like this:
List<String> outList = new ArrayList<String>();
for (String line : lines) {
String[] array = line.split(",");
outList.add(array[0]);
}
String[] outStr = outList.toArray(new String[0]);
System.out.println(Arrays.toString(outStr));
I am reading a Simple Notepad Text file containing a lot of data actually in a 3mb of size so you can imagine the number of words it can have! The problem is I am reading this file into a string then splits the string so that I can hold each single word inside an ArrayList(String). It works fine for me but the actual problem is that I am processing this array list for some purpose and then again I have to append or you can say put all the words of array list back to the String!
so that the steps are:
I read a text file into a String (alltext)
Split all words into an arraylist
process that array list (suppose I removed all the stop words like is, am, are)
after processing on array list I want to put all the words of array list back to the string (alltext)
then I have to work with that string (alltext)
(alltext is the string that must contains the text after all processing)
The problem is that at step number 4 it takes a lot of time to append all the words back to the string my code is:
BufferedReader br = new BufferedReader(new FileReader(file));
String line = "";
while ((line = br.readLine()) != null) {
alltext += line.trim().replaceAll("\\s+", " ") + " ";
}
br.close();
//Adding All elements from all text to temp list
ArrayList<String> tempList = new ArrayList<String>();
String[] array = alltext.split(" ");
for (String a : array) {
tempList.add(a);
}
//remove stop words here from the temp list
//Adding File Words from List in One String
alltext = "";
for (String removed1 : tempList) {
System.out.println("appending the text");
alltext += removed1.toLowerCase() + " ";
//here it is taking a lot of time suppose 5-10 minutes for a simple text file of even 1.4mb
}
So I just want any idea so that I can reduce the time for an efficient processing and relax the machine! I will be thankful for any suggestions and ideas...
Thanks
Use a StringBuffer instead of a String.
A String is immutable and thus you create a new Object everytime you append, which takes more and more time the longer your String becomes. A StringBuffer is mutable and made for cases like yours.
I would recommend StringBuilder
According to this stringbuilder-and-stringbuffer-in-java it's faster than a StringBuffer also check if you need the ArrayList because you can iterate through the array too