refactor: Add util.Input

Author: MarcellPerger1

src/main/java/net/marcellperger/mathexpr/interactive/Shell.java

@@ -1,14 +1,13 @@
 package net.marcellperger.mathexpr.interactive;
 
 import java.util.Arrays;
-import java.util.Scanner;
+
+import static net.marcellperger.mathexpr.util.Input.input;
 
 public class Shell {
     public static void main(String[] args) {
-        Scanner sc = new Scanner(System.in);
         System.out.println("args = " + Arrays.toString(args));
         System.out.print("Enter something: ");
-        String s = sc.nextLine();
-        System.out.println("You entered " + s);
+        System.out.println("You entered " + input());
     }
 }

src/main/java/net/marcellperger/mathexpr/util/Input.java

@@ -0,0 +1,69 @@
+package net.marcellperger.mathexpr.util;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PrintStream;
+import java.util.Objects;
+import java.util.Scanner;
+
+public class Input {
+    @NotNull Scanner sc;
+    @Nullable PrintStream ps;
+
+    public Input() {
+        this(System.in, System.out);
+    }
+    public Input(@NotNull InputStream iStream) {
+        this(new Scanner(iStream));
+    }
+    public Input(Readable readable) {
+        this(new Scanner(readable));
+    }
+    public Input(String s) {
+        this(new Scanner(s));
+    }
+    public Input(@NotNull Scanner scanner) {
+        this(scanner, null);
+    }
+    public Input(InputStream iStream, @Nullable OutputStream oStream) {
+        this(new Scanner(iStream), oStream);
+    }
+    public Input(@Nullable OutputStream oStream) {
+        this(System.in, oStream);
+    }
+    public Input(@NotNull Scanner scanner, @Nullable OutputStream oStream) {
+        this(scanner, oStream == null ? null : new PrintStream(oStream));
+    }
+    public Input(@NotNull Scanner scanner, @Nullable PrintStream pStream) {
+        sc = scanner;
+        ps = pStream;
+    }
+
+    public String getInput() {
+        return sc.nextLine();
+    }
+    public String getInput(String prompt) {
+        Objects.requireNonNull(ps, "An OutputStream is required to use Input.getInput(prompt)").println(prompt);
+        return sc.nextLine();
+    }
+
+    public static String input() {
+        // Don't cache `new Input()` - System.in could be changed
+        return new Input().getInput();
+    }
+    public static String input(@NotNull InputStream iStream) {
+        return new Input(iStream).getInput();
+    }
+    public static String input(String prompt) {
+        return new Input().getInput(prompt);
+    }
+    public static String input(String prompt, @NotNull OutputStream oStream) {
+        return new Input(oStream).getInput(prompt);
+    }
+    public static String input(String prompt, @NotNull InputStream iStream, @NotNull OutputStream oStream) {
+        return new Input(iStream, oStream).getInput(prompt);
+    }
+}