first commit

Semester 1/Programming 1/Java/examples/projects/chapter14/address-book-v3t/Parser.java

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+import java.util.Scanner;
+
+/**
+ * A class that reads input lines from the user.
+ * Input is filtered via getCommand for valid commands.
+ *
+ * @author David J. Barnes and Michael Kölling.
+ * @version 2016.02.29
+ */
+public class Parser 
+{
+    // Hold all valid command words.
+    private CommandWords commands;
+    private Scanner reader;
+
+    public Parser() 
+    {
+        commands = new CommandWords();
+        reader = new Scanner(System.in);
+    }
+
+    /**
+     * Read the next command from the user.
+     * The returned command will be valid.
+     * @return A valid command.
+     */
+    public String getCommand() 
+    {
+        String command = null;
+        do {
+           // Print a prompt.
+            System.out.print("> ");
+            
+            String word = reader.next();
+            // Discard the rest of the line.
+            readLine();
+            if(commands.isCommand(word)) {
+                command = word;
+            }
+            else{
+                System.out.println("Unrecognized command: " + word);
+                System.out.print("Valid commands are: ");
+                commands.showAll();
+            }
+        } while(command == null);
+    
+        return command;
+    }
+
+    /**
+     * Print out a list of valid command words.
+     */
+    public void showCommands()
+    {
+        commands.showAll();
+    }
+
+    /**
+     * @return A line of text from the user.
+     */
+    public String readLine()
+    {
+        return reader.nextLine();
+    }
+}