In Java AWT or Swing, which container types use a FlowLayout as their default layout manager?

Introduction / Context:
In Java graphical user interface programming with Abstract Window Toolkit and Swing, each container has a layout manager that controls how child components are arranged. Some containers use BorderLayout by default, while others use FlowLayout. Knowing these defaults is helpful for quickly designing user interfaces without always setting layout managers explicitly. This question asks you to identify which containers use FlowLayout as their default layout manager.

Given Data / Assumptions:

• AWT provides containers such as Frame, Panel, and Applet.
• Swing provides containers such as JFrame, JPanel, and JApplet.
• Layout managers such as BorderLayout and FlowLayout define different rules for positioning components.
• The question is about default behaviour before any layout is changed by the programmer.

Concept / Approach:
By default, AWT Frame uses BorderLayout, while AWT Panel and Applet use FlowLayout. Swing containers mirror some of this behaviour: the content pane of a JFrame uses BorderLayout by default, but a plain JPanel uses FlowLayout unless changed. FlowLayout positions components left to right, wrapping them to the next line when there is not enough horizontal space. The correct option must include Panel, Applet, and JPanel as FlowLayout based containers and exclude frames, tables, or specialised panes that use other layouts by default.

Step-by-Step Solution:
Step 1: Recall that java.awt.Frame and javax.swing.JFrame content panes default to BorderLayout, not FlowLayout. Step 2: Remember that java.awt.Panel and java.applet.Applet use FlowLayout by default. Step 3: Understand that javax.swing.JPanel also uses FlowLayout by default unless the programmer sets a different layout manager. Step 4: Examine option a, which lists Panel, Applet, and JPanel as using FlowLayout by default, matching these facts. Step 5: Reject options b, c, and d, which refer to containers whose default layouts are not FlowLayout or that use specialised internal layouts for their content.

Verification / Alternative check:
A quick test program that creates a JFrame and adds components directly to its content pane will show them arranged by BorderLayout unless changed. In contrast, adding components to a JPanel without setting a layout results in FlowLayout behaviour, with components arranged from left to right. Similarly, simple AWT examples that add controls to Panel or Applet without specifying layout display FlowLayout characteristics. These observations align with option a and confirm it is correct.

Why Other Options Are Wrong:
Option b incorrectly lists Frame and JFrame as using FlowLayout by default; they use BorderLayout for their content areas. Option c refers to JTable and JTree, which have their own internal structures and do not use FlowLayout for arranging rows or tree nodes. Option d mentions JScrollPane and JSplitPane, which manage scrollbars and split areas using specialised layouts rather than FlowLayout.

Common Pitfalls:
A common mistake is assuming that all containers share the same default layout, which leads to confusion when components do not appear where expected. Another pitfall is forgetting that in Swing, you usually add components to the content pane of a top level container, not directly to the JFrame itself, and that this content pane has its own default layout. Remember that Panel, Applet, and JPanel default to FlowLayout, while frames default to BorderLayout.

Final Answer:
The containers that use FlowLayout by default are Panel and Applet in AWT, and JPanel in Swing.