NatTable动态上下文菜单实现及菜单项组配置方式咨询

Great job getting the odd/even row context menu visibility working—your current implementation is totally valid! Let's tackle your follow-up question and look at ways to streamline this if you have multiple menu items that share the same visibility rules.

Short Answer to Your Question #

No, you don't need to configure every menu item group with separate anonymous IMenuItemState implementations. You can reuse state logic across multiple menu items to avoid redundant code and make your configuration more maintainable.

Option 1: Reuse IMenuItemState Instances #

If multiple menu items should follow the same visibility rule (like showing only on even rows), create a single state instance and attach it to all relevant menu items:

// Define reusable state instances once
IMenuItemState evenRowVisibility = paramNatEventData -> 
    paramNatEventData.getRowPosition() % 2 == 0;

IMenuItemState oddRowVisibility = paramNatEventData -> 
    paramNatEventData.getRowPosition() % 2 == 1;

// Build your menu with reused states
myPopupMenuBuilder
    // Even row menu items
    .withMenuItemProvider("A", (natTable, menu) -> {
        MenuItem item = new MenuItem(menu, SWT.PUSH);
        item.setText("A");
    })
    .withMenuItemProvider("C", (natTable, menu) -> {
        MenuItem item = new MenuItem(menu, SWT.PUSH);
        item.setText("C"); // Another item for even rows
    })
    .withVisibleState("A", evenRowVisibility)
    .withVisibleState("C", evenRowVisibility) // Reuse the same state
    
    // Odd row menu items
    .withMenuItemProvider("B", (natTable, menu) -> {
        MenuItem item = new MenuItem(menu, SWT.PUSH);
        item.setText("B");
    })
    .withVisibleState("B", oddRowVisibility);

Option 2: Create a Reusable State Class for Complex Logic #

If your visibility rules are more dynamic (like checking a property on the row's data instead of just row position), build a generic IMenuItemState implementation that accepts a custom check function:

// Generic state class to handle any row-based visibility check
class RowBasedVisibilityState implements IMenuItemState {
    private final Function<NatEventData, Boolean> visibilityCheck;

    public RowBasedVisibilityState(Function<NatEventData, Boolean> visibilityCheck) {
        this.visibilityCheck = visibilityCheck;
    }

    @Override
    public boolean isActive(NatEventData eventData) {
        return visibilityCheck.apply(eventData);
    }
}

// Usage example with custom row data logic
IMenuItemState highPriorityVisibility = new RowBasedVisibilityState(eventData -> {
    // Replace with your actual row data type
    YourRowDataType rowData = (YourRowDataType) eventData.getRowData();
    return rowData.isHighPriority(); // Check a business rule
});

myPopupMenuBuilder
    .withMenuItemProvider("HandlePriority", (natTable, menu) -> {
        MenuItem item = new MenuItem(menu, SWT.PUSH);
        item.setText("Process High Priority Row");
    })
    .withVisibleState("HandlePriority", highPriorityVisibility);

Key Takeaways #

• Your initial implementation works perfectly for simple cases, but reusing state logic will save you time as your menu grows.
• The PopupMenuBuilder's fluent API lets you group related menu items and their visibility rules, keeping your code clean and readable.

内容的提问来源于stack exchange，提问作者J.Doe