Create CommandHistory.java

src/main/java/seedu/address/ui/CommandHistory.java

@@ -0,0 +1,32 @@
+package seedu.address.ui;
+import java.util.ArrayList;
+
+
+/**
+ * Container for previous commands
+ */
+public class CommandHistory {
+    private ArrayList<String> commandHistory = new ArrayList<>();
+    private int currentHistoryIndex = -1;
+
+    public void addCommand(String command) {
+        commandHistory.add(command);
+        currentHistoryIndex = commandHistory.size(); // Reset index to point after the latest command
+    }
+
+    public String getPreviousCommand() {
+        if (currentHistoryIndex > 0) {
+            currentHistoryIndex--;
+            return commandHistory.get(currentHistoryIndex);
+        }
+        return null; // No previous command
+    }
+
+    public String getNextCommand() {
+        if (currentHistoryIndex < commandHistory.size() - 1) {
+            currentHistoryIndex++;
+            return commandHistory.get(currentHistoryIndex);
+        }
+        return null; // No next command
+    }
+}