Is it possible to catch a break-line as an "input-confirmation"?
The idea is that you skip an input, if it should not be used. Or is there an already existing java method for that problem?
Edit code:
import java.util.Scanner;
public class probe {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Input:");
boolean input = false;
if(scanner.hasNextLine()){
input=true;
}else if(!(scanner.hasNextLine())){
System.out.println(input);
}
System.out.println(input);
}
}
So .hasNextLine() is obviously not the right method to solve my problem, I just implemented it like that, because I think it is getting clearer.
But I think I'm already on the wrong way.
One Solution which come to my mind is, that to compare the char-value of an break-line to the inputed char.
I'm Sorry if I can't explain my problem more properly :(
As Tom already pointed out this should be the code snippet you're looking for:
if (scanner.hasNextLine()) {
String line = scanner.nextLine();
System.out.println(line.isEmpty() ? "Nothing to print out" : "Your input was: " + line);
}
Related
I'm pretty new to Java coming from Python so please pardon my retardedness. I'm trying to make a simple if statement and it won't work :(. It ignores the if statement and goes straight else.
I've tried to use .contains and .equalsIgnoreCase in the if statement.
package me.johnminton;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner user_input = new Scanner(System.in);
String species_animal;
System.out.println("Please enter your species: ");
species_animal = user_input.next();
if (species_animal.contains("Erectus")) {
System.out.println("random input statement");
}
else
{
System.out.println("okay");
}
}
}
I'm hoping for it output "random input statement" if I input Erectus in the first input. But instead, it goes straight to the else and outputs "okay".
The next() method just fetches a single word from the scanner, although you can change that behaviour by specifying a delimiter for the scanner.
In your case, if you type Eructussian or something similar, you'll get the result you want, but if you type Home Erectus, you won't.
I suspect you meant to use nextLine() instead of next(), which fetches an entire line of text.
The problem is that your scanner isn’t finishing without getting a return key. Try ‘user_input.nextLine()’ instead of ‘user_input.next()’
I am working on a program that is supposed to pull abbreviated text meanings from a list that is created from if-else statements. I am running into trouble with the logic of making the program see an incorrect input and provide a suggestion from the supported list. Here is the code we were given to edit.
import java.util.Scanner;
public class TweetDecoder {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
String origTweet = "";
System.out.println("Enter abbreviation from tweet: ");
origTweet = scnr.next();
if (origTweet.equals("LOL")) {
System.out.println("LOL = laughing out loud");
}
else if (origTweet.equals("BFN")) {
System.out.println("BFN = bye for now");
}
else if (origTweet.equals("FTW")) {
System.out.println("FTW = for the win");
}
else if (origTweet.equals("IRL")) {
System.out.println("IRL = in real life");
}
else {
System.out.println("Sorry, don't know that one.");
}
return;
}
}
This is for a class so I would like to know if someone can push me in the right direction rather than give the full answer or the string that I should be using. I feel like is should be something to do with String Comparison or String Access Operations but I cant seem to get it nailed down. If someone can assist I would greatly appreciate it. Thank you in advance!
it wouldn't let me add a comment, so i suppose here will do.
I would suggest looking into the .startsWith method. Its a method contained in the String class.
For example,
if(origTweet.startsWith("L")) //
System.out.println("Perhaps you meant LOL");
sorry if this isn't what you meant / wanted
"if" statement only allows to put numbers in it.
Is there a way to make it read letters?
I'm only in my fifth lesson of Java (I study in a uni and the teacher is very slow but I want to learn things fast)
for example.
import java.util.Scanner;
public class Java {
public static void main (String [] args) {
Scanner scan = new Scanner(System.in);
int answer1;
System.out.println("Do you like Java?");
answer1 = scan.nextInt();
if (answer1 == yes)
System.out.println("Cool ~");
else
System.out.println("Ehh...");
}
}
I want to put "yes" instead of the number 5.
So if the user types "yes" it will print "correct".
P.S. I didn't find a clear answer to that in the search engine.
It's not a duplicated thread as I'm trying to find a clear answer to that.
I need a detailed explanation about it.
I'm still a beginner, using those "high tech java words" won't help me.
You need to modify your program so that your scanner to reads a String instead of an int. You can do that as:
import java.util.Scanner;
public class Java {
public static void main (String [] args) {
Scanner scan = new Scanner(System.in);
String answer1;
System.out.println("Do you like Java?");
answer1 = scan.next();
if (answer1.equals("yes"))
System.out.println("Cool ~");
else
System.out.println("Ehh...");
}
}
I used next() for this since we only want one word (token), but be aware that there are other options for reading Strings.
Notice also that I've changed the test in the condition because it's now a String. See this answer for more on comparing Strings.
You need to modify your program so that your scanner to reads a String instead of an int. You can do that as:
import java.util.Scanner; public class Java {
public static void main (String [] args) {
Scanner scan = new Scanner(System.in);
String answer1;
System.out.println("Do you like Java?");
answer1 = scan.next();
if (answer1.equals("yes"))
System.out.println("Cool ~");
else
System.out.println("Ehh...");
} }
I used next() for this since we only want one word (token), but be aware that there are other options for reading Strings.
Notice also that I've changed the test in the condition because it's
now a String. See this answer for more on comparing Strings.
Ok, what if you want the program to read both words and numbers:
Here's my program (more in depth, when you see the full thing), but this is one of 5 parts (that look a like) where I'm having the program...
public static void Gdr1() {
try {
System.out.print("[Code: Gdr1] Grade 1: %");
Scanner gdr1 = new Scanner(System.in);
Z = gdr1.next();
Z = Double.toString(Grd1);
Grd1 = Double.parseDouble(Z);
if ((Grd1<100)&&(Grd1>=5)) {
Gdr2();
} else if ((Grd1>=100)&&(Grd1<125)) {
System.out.println(" System> Great Job "+Stu+"!");
Gdr2();
} else if (Grd1<5) {
System.out.println("I'm sorry, the lowest grade I am allowed to compute is 5...");
Gdr1();
} else if (Z.equalsIgnoreCase("restart")) {
restart01();
} else {
System.out.println("("+Z+") cannot be resolved in my system...");
Gdr1();
}
} catch (Exception e) {}
}
Now everything works in the program, besides for when the End-User's input = "restart", I know some of the code in the program seems complicated, but it does work (most of it), can anyone help me try to figure this out, its for my portfolio at my school due latest by 1/25/2017 # 11:59 pm.
The things like Z (constant String), ""+Stu+"" (variable input), and [Code: Gdr1] are there for a purpose...
I'm a newbie writing Java code. I haven't read about loops yet. I'm just up to if-else statements. My code works except when I enter a sentence only the first word is recognized. If I enter a sentence with no spaces it works perfectly. How can I get the code to see the whole sentence? Thanks!
import java.util.Scanner;
public class Program04
{
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Write a complete sentence with proper grammer:");
String sentence = keyboard.next();
boolean qMark = sentence.contains("?");
boolean wow = sentence.contains("!");
if (qMark)
System.out.println("Yes");
else if (wow)
System.out.println("Wow");
else
System.out.println("You always say that.");
}
}
Use
keyboard.nextLine();
instead of
keyboard.next();
have a look at the API, particularly the part about nextLine().
Scanner.next() only returns the next token, which, by default, is just one word (whitespace-delimited). If you want the whole sentence you can change the delimiter to '\n': keyboard.setDelimiter("\n");, or you can learn loops and then loop over the whole sentence.
Edit:
Or, as others have pointed out, nextLine(). That's more portable because macs use '\r', which won´ t be caught with what I said.
import java.util.Scanner;
public class Program04{
public static void main(String[] args){
Scanner keyboard = new Scanner(System.in);
System.out.println("Write a complete sentence with proper grammer:");
String sentence = keyboard.nextline();
*//this graps full text but next ignores the other words after a space is given*
boolean qMark = sentence.contains("?");
boolean wow = sentence.contains("!");
if (qMark)
System.out.println("Yes");
else if (wow)
System.out.println("Wow");
else
System.out.println("You always say that.");
}
}
I'm doing a simple program regarding methods.
But I have one problem. Everything is already working except when looping.
When I choose to loop again. The program skips on inputting the name. And proceeds directly to the year and section.
Here's the code:
public static void main(String[] args) {
do{
System.out.println("Input info:");
name=stringGetter("Name: ");
yearandsec=stringGetter("Year and section: ");
sex_code=charGetter("Sex code: " + "\n" + "[M]" + "\n" + "[F]:");
scode=intGetter("Scholarship code: ");
ccode=intGetter("Course code: ");
units=intGetter("Units: ");
fee_per_unit=doubleGetter("Fee per unit: ");
misc=doubleGetter("Miscellaneous: ");
display();
switches(scode, units, fee_per_unit, misc);
System.out.println("Another?");
dec=rew.nextInt();
}while(dec==1);
}
Here's the method getting the value for name together with the year and section:
public static String stringGetter(String ny){
String sget;
System.out.println(ny);
sget=rew.nextLine();
return sget;
}
I'm really annoyed with this problem, and I don't have any idea on how to fix this. Please help. thanks
Here is a simpler and more complete program that reproduces the error:
public static Scanner rew = new Scanner(System.in);
public static void main(String[] args) {
int dec;
do {
System.out.println("Input info:");
String name=stringGetter("Name: ");
String yearandsec=stringGetter("Year and section: ");
dec=rew.nextInt();
} while(dec==1);
}
public static String stringGetter(String ny){
System.out.println(ny);
return rew.nextLine();
}
The problem is that after calling nextInt() the call to nextLine() reads up to the new line after the int (giving a blank line), not up to the next new line.
If you change dec to a String and change dec=rew.nextInt(); to dec=rew.nextLine(); then it will work fine. Here is a complete example that you can copy and paste into a blank file to see that it works correctly:
import java.util.*;
public class Program
{
public static Scanner rew = new Scanner(System.in);
public static void main(String[] args) {
String dec;
do {
System.out.println("Input info:");
String name = stringGetter("Name: ");
String yearandsec = stringGetter("Year and section: ");
dec = stringGetter("Enter 1 to continue: ");
} while(dec.equals("1"));
}
public static String stringGetter(String ny){
System.out.println(ny);
return rew.nextLine();
}
}
You may also want to consider adding proper parsing and validation to your program. Currently your program will behave in an undesirable way if the user enters invalid data.
The line:
dec = rew.nextInt();
Is reading an int value from the input stream and is not processing the newline character, then when you come back to point where you get the name at which point a new line is still in the Reader's buffer and gets consumed by the stringGetter returning an empty value for name.
Change the line to do something like:
do {
//....
s = stringGetter("Another (y/n)? ");
} while ("y".equals(s));
Well you haven't told us what "rew" is, nor what rew.nextInt() does. Is it possible that rew.nextInt() is waiting for the user to hit return, but only actually consuming one character of the input - so that the next call to rew.nextLine() (for the name) just immediately takes the rest of that line? I suspect that's what's happening because you're using System.in - usually reading from System.in only gives any input when you hit return.
(It's possible that this is also only a problem on Windows - I wonder whether it consumes the "\r" from System.in as the delimiter, leaving "\n" still in the buffer. Not sure.)
To test this, try typing in "1 Jon" when you're being asked whether or not to continue - I think it will then use "Jon" as the next name.
Essentially, I think using Scanner.nextInt() is going to have issues when the next call is to Scanner.nextString(). You might be better off using a BufferedReader and calling readLine() repeatedly, then parsing the data yourself.