MATCH_PARENT宽度不起作用

Question

我尝试创建一个带有重力端的片段以将其与NavigationMenu一起使用，但我的问题是找不到match_parent，因为片段不是全屏宽度。

这是我的xml：

/**
 * Creates a dialog and shows it
 *
 * @param exception
 *            The exception to show in the dialog
 * @param title
 *            The dialog title
 */
private void createAndShowDialogFromTask(final Exception exception, String title) {
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            createAndShowDialog(exception, "Error");
        }
    });
}


/**
 * Creates a dialog and shows it
 *
 * @param exception
 *            The exception to show in the dialog
 * @param title
 *            The dialog title
 */
private void createAndShowDialog(Exception exception, String title) {
    Throwable ex = exception;
    if (exception.getCause() != null) {
        ex = exception.getCause();
    }
    createAndShowDialog(ex.getMessage(), title);
}

/**
 * Creates a dialog and shows it
 *
 * @param message
 *            The dialog message
 * @param title
 *            The dialog title
 */
private void createAndShowDialog(final String message, final String title) {
    final AlertDialog.Builder builder = new AlertDialog.Builder(this);

    builder.setMessage(message);
    builder.setTitle(title);
    builder.create().show();
}

但宽度与父母不匹配：

如果有任何想法，请帮助我，提前致谢。