Use IO.readln

Author: bowbahdoe

src/global_fields/challenges.md

@@ -0,0 +1 @@
+# Challenges

src/standard_input.md

@@ -4,17 +4,3 @@ Programs are pretty boring if they just make a machine warm and do some math.
 
 There are a lot of ways to make a program interactive, but the easiest is to read
 from what is called "standard input."
-
-This function will be added to Java in a future version, but until then
-copy paste this at the very top of all the code in this section.
-
-```java,no_run
-import java.util.Scanner;
-
-Scanner scanner = new Scanner(System.in);
-
-String input(String message) {
-    System.out.print(message);
-    return scanner.nextLine();
-}
-```

src/standard_input/delayed_assignment.md

@@ -9,17 +9,10 @@ One strategy for this is to declare any response-holding variables outside the l
 The problem with this is that Java isn't smart enough to know that you always initialize those variables.
 
 ```java,no_run,does_not_compile
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
     String name;
     while (true) {
-        String name = input("What is your name? ");
+        String name = IO.readln("What is your name? ");
         if (name.isBlank()) {
             System.out.println("Name cannot be blank!");
             continue;
@@ -35,19 +28,10 @@ void main() {
 To get around this you can either give an explicit default value.
 
 ```java,no_run
-~import java.util.Scanner;
-~
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
     String name = null;
     while (true) {
-        String name = input("What is your name? ");
+        String name = IO.readln("What is your name? ");
         if (name.isBlank()) {
             System.out.println("Name cannot be blank!");
             continue;
@@ -65,19 +49,10 @@ In this context our old friend delayed assignment becomes an option again. This
 to see that the code in the loop will run at least once.
 
 ```java,no_run
-~import java.util.Scanner;
-~
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
     String name;
     do {
-        String name = input("What is your name? ");
+        String name = IO.readln("What is your name? ");
         if (name.isBlank()) {
             System.out.println("Name cannot be blank!");
             continue;

src/standard_input/interpreting_input.md

@@ -1,25 +1,16 @@
 # Interpreting Input
 
-When you call `input` the human on the other side can type whatever they want.
+When you call `IO.readln` the human on the other side can type whatever they want.
 
 This means that, depending on the question you asked, you might need to interpret
 what they typed as something other than a generic `String`.
 
 In its most basic form this will look like seeing if one `String` equals another `String`.
 
 ```java,no_run
-~import java.util.Scanner;
-~
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
     while (true) {
-        String shouldExit = input("Exit the program? (y/n)");
+        String shouldExit = IO.readln("Exit the program? (y/n)");
         if (shouldExit.equals("y")) {
             break;
         }

src/standard_input/leniency.md

@@ -7,16 +7,9 @@ This means accounting for common mistakes people make like having extra spaces o
 For this purpose, methods like `strip` and `equalsIgnoreCase` are useful.
 
 ```java,no_run
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
     while (true) {
-        String response = input("Answer me: yes or no").strip();
+        String response = IO.readln("Answer me: yes or no").strip();
         if (response.equalsIgnoreCase("yes")) {
             System.out.println("aight");
         }

src/standard_input/prompting.md

@@ -1,25 +1,18 @@
 # input
 
-To prompt a user for information you use the `input` function.
+To prompt a user for information you use the `IO.readln` function.
 
-The `input` function takes a `String` to output as a prompt. This will
-work the same as if the `String` was passed to `System.out.print`.
+`IO.readln` takes a `String` to output as a prompt. This will
+work the same as if the `String` was passed to `IO.print`.
 
 The program will then wait until a human types some text and clicks the enter key.
 Whatever they typed will be returned to the program as a `String`.
 
 ```java,no_run
-~import java.util.Scanner;
-~
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
-    String name = input("What is your name? ");
+    String name = IO.scanln("What is your name? ");
     System.out.println("Hello, " + name);
 }
-```
+```
+
+`readln` stands for "read line." It reads the next line a person types.

src/standard_input/reprompting.md

@@ -6,18 +6,9 @@ This is a good use case for loops. You ask a question and, if the answer you get
 you proceed as normal. If it is not then you loop back and ask again.
 
 ```java,no_run
-~import java.util.Scanner;
-~
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
     while (true) {
-        String response = input("Answer me: yes or no");
+        String response = IO.readln("Answer me: yes or no");
         if (response.equals("yes")) {
             System.out.println("okay then!");
         }

src/standard_input/transporting_data.md

@@ -4,18 +4,9 @@ If you ask someone multiple questions you likely will get multiple variables
 worth of information.
 
 ```java,no_run
-~import java.util.Scanner;
-~
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
-    String firstName = input("What is your first name? ");
-    String lastName = input("What is your last name? ");
+    String firstName = IO.readln("What is your first name? ");
+    String lastName = IO.readln("What is your last name? ");
 
     System.out.println("Hello " + firstName + " " + lastName + ".");
 }
@@ -25,19 +16,10 @@ This is fine and dandy so long as you immediately use those variables. But once
 reprompting logic code can get pretty lengthy.
 
 ```java,no_run
-~import java.util.Scanner;
-~
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 void main() {
     String firstName;
     do {
-        firstName = input("What is your first name? ");
+        firstName = IO.readln("What is your first name? ");
 
         if (firstName.isBlank()) {
             System.out.println("First name cannot be blank.");
@@ -49,7 +31,7 @@ void main() {
 
     String lastName;
     do {
-        lastName = input("What is your first name? ");
+        lastName = IO.readln("What is your first name? ");
 
         if (lastName.isBlank()) {
             System.out.println("First name cannot be blank.");
@@ -69,15 +51,6 @@ I mention all this as a reminder that when you want to return multiple values fr
 you can use a class.[^dto]
 
 ```java,no_run
-~import java.util.Scanner;
-~
-~Scanner scanner = new Scanner(System.in);
-~
-~String input(String message) {
-~    System.out.print(message);
-~    return scanner.nextLine();
-~}
-~
 class Person {
     String firstName;
     String lastName;
@@ -91,7 +64,7 @@ class Person {
 Person askForName() {
     String firstName;
     do {
-        firstName = input("What is your first name? ");
+        firstName = IO.readln("What is your first name? ");
         
         if (firstName.isBlank()) {
             System.out.println("First name cannot be blank.");
@@ -103,7 +76,7 @@ Person askForName() {
 
     String lastName;
     do {
-        lastName = input("What is your first name? ");
+        lastName = IO.readln("What is your first name? ");
 
         if (lastName.isBlank()) {
             System.out.println("First name cannot be blank.");