为什么我的TableLayout不能让组件居中？

Question

为什么我的TableLayout无法将组件居中？我只在单列中放置了几个组件，希望它们居中，但是TableLayout的居中约束似乎在这种情况下不起作用。需要说明的是，我也尝试过BoxLayout，但是我没有看到任何可以将组件居中的方法。此外，我计划在下面添加更多组件，所以BorderLayout不可行。以下是它的样子，与我在Android手机上看到的一样。

public class Playground {

  private Form current;
  private Resources theme;

  public void init(Object context) {
    theme = UIManager.initFirstTheme("/theme");

    // Enable Toolbar on all Forms by default
    Toolbar.setGlobalToolbar(true);

  }

  public void start() {
    if (current != null) {
      current.show();
      return;
    }

    Form hi = new Form("Table Layout Test");
    TableLayout layout = new TableLayout(4, 1);
    hi.setLayout(layout);

    // I specify row and column explicitly or the replaceAndWait() method will put the 
    // replacement below the button instead of above it.
    TableLayout.Constraint center;
    center = layout.createConstraint(0, 0).horizontalAlign(hi.CENTER);
    red = new Label(makeBlankImage(200, 200, 0xFF0000));
    blue = new Label(makeBlankImage(200, 200, 0xFF));
    visibleLabel = red;
    hi.add(center, visibleLabel);

    center = layout.createConstraint(1, 0).horizontalAlign(hi.CENTER);
    Button button = new Button("Switch");
    button.addActionListener(evt -> {
      Label priorImage = visibleLabel;
      //noinspection ObjectEquality
      if (visibleLabel == red) {
        visibleLabel = blue;
      } else {
        visibleLabel = red;
      }
      hi.replaceAndWait(priorImage, visibleLabel, CommonTransitions.createFade(500));
    });
    hi.add(center, button);

    center = layout.createConstraint(2, 0).horizontalAlign(hi.CENTER);
    Label label = new Label("Why aren't any of these");
    hi.add(center, label);

    center = layout.createConstraint(3, 0).horizontalAlign(hi.CENTER);
    SpanLabel label2 = new SpanLabel("components centered?");
    hi.add(center, label2);

    hi.show();
    current = hi;
  }

  private Label red;
  private Label blue;
  private Label visibleLabel;

  private Image makeBlankImage(final int width, final int height, int color) {
    Image image = Image.createImage(width, height);
    Graphics graphics = image.getGraphics();
    graphics.setColor(color);
    graphics.fillRect(0, 0, width, height);
    return image;
  }


  public void stop() {
  }

  public void destroy() {
  }

}

- MiguelMunoz

Answer 1

尝试添加以下内容：

layout.setGrowHorizontally(true);

首选大小没有占用整个屏幕。

- Derek Johnson

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