In Java AWT, which top level containers use BorderLayout as their default layout manager?

Introduction / Context:
In Java AWT, different container classes have different default layout managers. Knowing which container uses which layout by default helps developers design user interfaces quickly without always setting layouts manually. BorderLayout is a common layout manager for top level windows. This question checks whether candidates remember which AWT containers default to BorderLayout and which use other layouts like FlowLayout.

Given Data / Assumptions:

• We are talking about AWT containers such as Frame, Window, Dialog, Applet and Panel.
• A layout manager controls how components are arranged inside a container.
• BorderLayout and FlowLayout are standard layout managers in AWT.
• Top level windows often need a layout that can place components in regions such as north, south, east, west and center.

Concept / Approach:
By default, AWT sets the layout manager for a container when that container is created. For top level containers such as Frame, Window and Dialog, the default layout manager is BorderLayout. This gives a flexible way to place components in different regions of the window. For simpler containers such as Panel and Applet, the default layout manager is typically FlowLayout, which positions components in a left to right flow. Understanding these defaults removes the need to set the layout explicitly unless a different arrangement is desired.

Step-by-Step Solution:
Step 1: Recall that Frame is a top level window with title bar and border and that its default layout manager is BorderLayout. Step 2: Recall that Dialog is a pop up window used for messages and forms and that it also uses BorderLayout by default. Step 3: Recognise that Window, a more general top level container without a title bar, uses BorderLayout by default as well. Step 4: Contrast this with Panel and Applet, which default to FlowLayout, placing components in a row. Step 5: Conclude that the group Frame, Window and Dialog share BorderLayout as their default, matching option A.

Verification / Alternative check:
Examining AWT source code or documentation reveals that the constructors for Frame, Window and Dialog call setLayout with a BorderLayout instance, whereas Panel and Applet call setLayout with a FlowLayout instance. In typical example code, adding components to a Frame without setting a layout manager still results in components being laid out in BorderLayout regions, with the first added component occupying the center region by default. This behaviour confirms that BorderLayout is the default for these top level containers.

Why Other Options Are Wrong:
Option B incorrectly groups Panel, Applet and ScrollPane as using BorderLayout by default. Panel and Applet use FlowLayout, and ScrollPane manages scrolling rather than using BorderLayout in the same way. Option C states that only Panel uses BorderLayout by default, which is false because Panel uses FlowLayout by default. Option D claims that no container uses BorderLayout by default, which is contradicted by the standard behaviour of Frame, Window and Dialog. Option E claims even components like Button and Label use BorderLayout, but these are not containers for other components. Only option A correctly lists the containers that default to BorderLayout.

Common Pitfalls:
Beginners often assume that all containers behave the same and forget about default layouts, leading to confusion when components appear in unexpected positions. Another pitfall is forgetting that Swing top level containers such as JFrame use a content pane with BorderLayout by default, which is related but not identical to AWT. In interviews, clearly stating that Frame, Window and Dialog use BorderLayout by default, while Panel and Applet typically use FlowLayout, shows a solid understanding of AWT layout behaviour.

Final Answer:
In Java AWT, the top level containers Frame, Window and Dialog use BorderLayout as their default layout manager for their content areas.