Metal (Java Look and Feel) vs Luna
メタル（Java ルック＆フィール） / ルナ
Metal (Java Look and Feel) comes from Platform Screen Languages and Luna from Microsoft UI. Both are read here as style. They are reached for with some of the same intent, which is where they get confused.
Metal (Java Look and Feel)
Sun's default look and feel for Swing, built so that a program looks the same on every operating system. Metal was Sun's internal project name for it and stuck as the public one. Blue violet fills, thin straight borders, and a flat refusal to imitate the host platform are its signature.
Luna
Windows XP's look: blue taskbar, green Start button, rounded windows and a meadow wallpaper repainting the gray office machine as household optimism.
| Metal (Java Look and Feel) | Luna | |
|---|---|---|
| Era | 1998– | 2001–2006 |
| Family | Platform Screen Languages | Microsoft UI |
| Kind | Style | Style |
| Cues | Internal window title bars laid as a deep blue violet band over a pale blue violet field / A fine texture of dots and diagonal ticks stamped into title bars and dividers / Rectangular buttons with no corner radius, ringed by a one pixel deep blue violet line / The host system draws the outer window frame while everything inside it follows a different visual language | The blue taskbar / The green Start button / Rounded frames / Meadow-and-sky optimism |
| Best used for | Flattening the differences between operating systems so an internally distributed desktop tool reads as one picture everywhere · Recreating the screen of a turn of the century business application for a document or an exhibit | Using early 2000s PC culture as a device for nostalgia · Assembling a bright, friendly home facing screen through saturation |
| Type | Run a single sans throughout and separate levels with weight and color only. Keep to two type sizes and leave headings undecorated. | Bold sans in white, contrasted hard against the blue ground |
| Composition | Fix four bands inside the window: menu, tool strip, work area, status strip. Leave the host window frame alone and paint only what is inside it. | A horizontal bar along the bottom, one primary control at its left |
| Material | Combine three steps of blue violet, a pale field, a deep band, a darker border, with three steps of gray. Draw every boundary as a one pixel line and never blur it. | Saturated blue and green, frames swelled by rounding and gradient |
| Caution | Since Java SE 5 the default theme has been Ocean, which drains most of the blue violet away, so building on the assumption that Metal means blue violet will not match what actually runs. | Copying only the palette while dropping the rounding and swell leaves the colors floating, and none of the optimism arrives. |