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Scanner interfering with another

So I am trying to make a code that will prompt the user to either use a basic calculator, or a word counter that displays how many words are in a given sentence entered by the user, this is done using methods. I have figured out how to properly set up the calculator, but the word counter is giving me some issues:
public static int wordCounter(String str){
String words[]=str.split(" ");
int count=words.length;
return count;
}
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("What do you want to do( calculator(0)/word counter(1) )? ");
//This runs and I select '1' for word counter
int choice = input.nextInt(); //Input the choice here
if (choice == 0) {
// It runs this selection statment, and since zero is not selected,
//it runs the word Counter branch
calculator();
}else{
System.out.println("Please enter a sentence:"); // Tells me to enter a sentence
String sentence=input.nextLine();
//^ This input is completely skipped and goes
//right to the 'System.out.print(); Statement.
System.out.print("There are "+ wordCounter(sentence) + " words in the sentence.");
//^ This prints a 1 immediately after the branch is selected with '1'
}
}
I'm not sure where it is going wrong since this only happens while it is in the if/else statement. Doing some testing also showed me that it seems that the first scanner "int choice=input.nextInt()" Is somehow interfering with the second scanner for the string. Any ideas keeping a similar formatting would be greatly appreciated.
Please forgive my formatting, it may not look great.

nextLine() will only return the remainder of the current line being scanned. Since you would have pressed enter after selecting the number, all it will capture is an empty string.
To fix it, just add a nextLine() directly after you get the integer.
public String nextLine()
Advances this scanner past the current line and returns the input that was skipped. This method returns the rest of the current line, excluding any line separator at the end. The position is set to the beginning of the next line.
Since this method continues to search through the input looking for a line separator, it may buffer all of the input searching for the line to skip if no line separators are present.
https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html#nextLine()

The problem is when you enter the number int choice = input.nextInt() it's only scanning the integer, not the newline. So when you call input.nextLine() it instantly returns an empty string. One way to fix this would be to replace that line with
int choice = Integer.parseInt(input.nextLine());

Strange output when I read from scanner

I'm trying to create a videoStore with the basic CRUD operation. For creating each movie I need to read the title, the year and the gender as below:
System.out.print("name: ");
name = in.nextLine();
System.out.print("year: ");
year = in.nextInt();
in.nextLine();
System.out.print("gender: ");
gender = in.next();
When I enter the addMovie option, I get this print on the console
(name: year:)
Can someone explain to me why it happens as above?
Here is the rest of the method:
static ArrayList<Movie> movies = new ArrayList<Movie>();
static Scanner in = new Scanner(System.in);
public static void InserirFilme() {
String name;
int year;
String gender;
boolean existe = false;
System.out.print("name: ");
name = in.nextLine();
System.out.print("year: ");
year = in.nextInt();
in.nextLine();
System.out.print("gender: ");
gender = in.next();
Movie movie = new Movie(name, year, gender);
for(Movie m: movies)
{
if(movie == m)
{
existe = true;
}
}
if(!existe)
{
movies.add(movie);
}
else
{
System.out.println("the movie already exists in the videoStore");
}
}

Calling next does not remove the line break, which means the next time you call InserirFilme the call to read the name can complete immediately. Use nextLine.
System.out.print("gender: ");
gender = in.nextLine();
(You probably mean "genre" instead of "gender" though)
Also, as mentioned in the comments, this check will never succeed:
if(movie == f)

You run this method in loop (right?)
The first call reads input correctly, but it leaves the linebreak in System.in after the last in.next().
On next call the name: is printed, then scanner reads an empty string from System.in because the linebreak already exists here.
And after thet the year: is printed on the same line because no new linebreaks are entered.
So you just have to insert another in.nextLine() after reading gender (or genre :) )
Or use nextLine() for read genre instead of next(), because genre might have more than one word.
But there are some disadvantages with using fake nextLine() to 'eat' linebreak - there might be another text which you doesn't process. It's a bad practice - to loose the data user entered.
It is better to read all the data from line, then validate/parse it, check isn't there some extra data, and if the data is invalid show notification and let him try to enter the right value.
Here are some examples how to deal with user input manually - https://stackoverflow.com/a/3059367/1916536. This is helpful to teach yourself.
Try to generalize user input operations:
name = validatedReader.readPhrase("name: ");
year = validatedReader.readNumber("year: ");
genre = validatedReader.readWord("genre: ");
where ValidatedReader is a custom wrapper for Scanner which could use your own validation rules, and could gently re-ask user after a wrong input.
It could also validate dates, phone numbers, emails, url's or so
For production purposes, it is better to use validation frameworks with configurable validation rules. There are a lot of validation frameworks for different purposes - Web, UI, REST etc...

when i enter the addMovie option, i get this print on the console (name: year:) can someone explain me why it happens i already searched a lot and i cant understand why :S
The way i understood your question is that you are getting the output (name: year: ) in a line and want it in seperate lines? In that case you simply can use System.out.println(String); instead of System.out.print(String). On the other hand you can also use "\n" whenever you want a linebreak within a String. Hope i could help you :).
Edit: If this was not an answer to your question, feel free to tell me and clarify your question :)

For String name you are using in.nextLine(); i.e the data entered on the entire line will be added to name string.
After "name: " is displayed, enter some text and press enter key, so that the year and gender fields will get correct values.
The code written is correct but you are not giving appropriate input through the scanner.
I recommend to use
String name = in.next();//instead of String name = in.nextLine();

You may instantiate Scanner Class differently for String and Integer type input. It works for me :)
Example:
static Scanner in1 = new Scanner(System.in);
static Scanner in2 = new Scanner(System.in);
Please use nextLine() for 'name' and 'gender'. It may contain more than one word. Let me know if it works.
Example:
System.out.print("name: ");
name = in1.nextLine();
System.out.print("year: ");
year = in2.nextInt();
System.out.print("gender: ");
gender = in1.nextLine();

Scanner nextLine() issues

I've been working on a programming assignment that acts as a Scrabble dictionary for a while now. The program takes input from the user and outputs a file with a list of words, depending on what the user requests from a menu. The problem I've been having has to do with Scanner.nextLine().
I'm not aexactly sure why, but for some reason I have to press enter once sometimes before my code will take my input and store it as the variable. Essentially, I end up entering the input twice. I tried inserting Scanner.nextLine() around the code to "take up" the empty enter/spaces but it doesnt work, and I have to press enter multiple times to get it to process what I want.
Does anybody have any suggestions? I'd appreciate any and all help.
Here is a bit of the code:
System.out.println("Enter the length of the word you are" + " searching for.");
int n = -1;
while(!(n >=0)) {
if(in.hasNextInt())
n = in.nextInt();
else {
System.out.println("You have not entered a valid number.
Please enter a real number this time.");
in.nextLine();
}
}
in.nextLine();
System.out.println("Enter the first letter of the words" + " you are searching for.");
String firstLetter = "";
while(!(firstLetter.length() == 1)) {
if(in.nextLine().length() > 1) {
System.out.println("You have not entered a valid letter.
Please press enter and enter only one real letter.");
}
else if(in.hasNextInt()) {
System.out.println("Do not enter a number. Please enter one real letter.");
}
else {
in.nextLine();
firstLetter = in.nextLine();
break;
}
}
At the end of this, I have to press enter once and then input to get it to store anything in the variable firstLetter. I assume it has something to do with the nature of nextLine(), as the conditions using nextInt() give no issues.

It's because you're using both nextLine() and nextInt(), what's going on is that nextLine() is searching for a new line (enter) and nextInt will automatically stop the search if any integer is typed through System.in.
Rule of thumb: Just use Scanner.nextLine() for your input, then convert your string from Scanner.nextLine() accordingly through Integer.parseInt(string), etc.

I think you're overcompensating with too many nextLines. You may want to do that once to clear the line after the int is inputted, for example, to clear the newline, but the second time here just absorbs an extra line of input:
System.out.println("You have not entered a valid number. Please enter a real number this time.");
in.nextLine();//first time
}
}
in.nextLine();//this second time is unnecessary.
The same thing happens with your duplicate uses here:
in.nextLine();
firstLetter = in.nextLine();
break;
You should only add an extra in.nextLine() immediately between inputting nextSOMETHINGELSE() and another nextLine().
EDIT:
Additionally, note that whenever you call in.nextLine(), you are absorbing a line of input. For example, this line should be fixed:
if(in.nextLine().length() > 1){
because it reads in a line, using it up, and then checks whether that (now used-up) line is long enough.

Trouble with Scanner taking data from a command line using Java

I will admit, this is a school assignment... But I simply cannot figure out what I am doing wrong.
I have a hash table with an insert function. The following code is supposed to take a line of data from System.in in the format "Long String" (i.e. "32452 John"). The first token must be a Long for the ID number, and it must be followed by a String token for the name. When I run the program and I get to the portion where this must be executed (It is in a switch statement), I entered 'a' and hit enter. The command line immediately reads "Invalid value." (note: not VALUES, as that would mean it hit the nested if statement. It won't let me type in any data. Thank you in advance!
System.out.println("Enter ID and Name.");
//temp to take in the next line entered by the user
//inScan is the Scanner for System.in
temp = inScan.nextLine();
//Create Scanner for the line
Scanner tempScan = new Scanner(temp);
if(tempScan.hasNextLong()){
thisID = tempScan.nextLong();
if((tempScan.hasNext()) && (thisID>0)){
thisName = tempScan.next();
//The data will only be inserted if both segments of data are entered
myTable.insert(new Student(thisID, thisName));
}else{
System.out.println("Invalid values.");
}
}else{
System.out.println("Invalid value.");
}

Why do you need the second Scanner?
Example
String input = scanner.nextLine();
String[] tokens = input.split(" ");
Long id = Long.parseLong(tokens[0]);
String name = tokens[1];
And if you wanted to add your validation:
String input = scanner.nextLine();
if(input.contains(" ")) {
// You know there's a space in it.
String[] tokens = input.split(" ");
if(tokens.length == 2) {
// You know it's a value, followed by a space, followed by a value.
if(tokens[0].matches("[0-9]+")) {
// You know it only contains numbers.
Long id = Long.parseLong(tokens[0]);
}
}
}

I've not run it, but i guess your problem is that when you enter the text 'a' and hit enter, this line is false:
if(tempScan.hasNextLong()){
as you haven't entered a number. hence why it drops to the next block. If you enter something numerical first, i suspect your code with work. you probably need to add a 'while' loop around it, to run until it gets a number.

You already have a Scanner which reads from System.in, there's no need for another one. The second one you've made is a scanner for a String, which will never have a nextLong as it has nothing to scan after your String.
I won't write any code for you as this is homework, but stick to your original scanner when checking for user input instead.

System.out.println repeating itself

Would anyone point me in the right direction, of why when i use a for loop the println function comes up two times in the output. Thanks
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Enter the number of employees to calculate:");
int numberEmployees = scan.nextInt();
for(int i=0; i<numberEmployees; i++){
System.out.println("Enter First Name:");
name = scan.nextLine();
System.out.println("Enter Last Name:");
last = scan.nextLine();
System.out.println("Enter Document #:");
document = scan.nextInt();
System.out.println("Enter Basic Salary");
basicSalary = scan.nextInt();
System.out.println("Enter # of Hours");
hours = scan.nextInt();
}
}
OUTPUT
Enter the number of employees to calculate:
1
Enter First Name:
Enter Last Name:
daniel
Enter Document #:

The problem is that when you entered 1 with a new line, the nextInt() function doesn't remove the newline that you had from entering in the 1. Change your calls to scan.nextInt() to Integer.parseInt(scan.nextLine()) and it should behave the way you want.
To further explain; here's stuff from the Java API.
A Scanner breaks its input into tokens using a delimiter pattern,
which by default matches whitespace. The resulting tokens may then be
converted into values of different types using the various next
methods.
and
The next() and hasNext() methods and their primitive-type companion
methods (such as nextInt() and hasNextInt()) first skip any input that
matches the delimiter pattern, and then attempt to return the next
token. Both hasNext and next methods may block waiting for further
input.
So, what evidently happens (I didn't see anything on the page to confirm it) is that after next(), hasNext(), and their related methods read in a token, they immediately return it without gobbling up delimiters (in our case, whitespace) after it. Thus, after it read in your 1, the newline was still there, and so the following call to nextLine() had a newline to gobble and did so.

It appears that the newline character remains in your input after the first entry. When the next input is requested, the Scanner sees a newline character and interprets it as the end of the input. This makes it appear to skip every other input request. I would suggest checking out the Java API docs as to the exact behavior of Scanner's methods.