按钮在应用程序上不可见.怎么了? [英] Buttons not visible on the application. What's wrong?

问题描述

我为我的测试应用"创建了一个空活动，预览部分中的内容如下:

I created an empty activity for 'My Testing App' and it looks like the following in the preview section:

但是当我生成一个构建apk并在手机中使用了该构建apk时，结果如下:

But when I generated a build apk and used the same in my cell phone the result was like the following:

我只能查看左上角的退出按钮，但应该位于其上方的其他两个按钮丢失. 我也尝试重新排列屏幕上的图标.我使它们位于最右边，最底部，但是重新安装apk时，我看不到任何变化.

I can only view the exit button on the very top left but the two other buttons, that should be above it are missing. I tried to rearrange the icons on the screen as well. I made them to go to the bottom, to the right most, but I see no change when the apk is reinstalled.

如何使它们在硬件上可见?

以下是该活动的代码摘要:

Here is the snap of the code for this activity:

推荐答案

要快速在布局中添加约束，只需单击推断约束 按钮在版式编辑器工具栏中.在此处了解有关此功能的更多信息: https ://developer.android.com/training/constraint-layout/index.html#use-autoconnect-and-infer-constraints

To quickly add constraints to your layout just click on the Infer Constraints button in the Layout Editor toolbar. Learn more about the feature here: https://developer.android.com/training/constraint-layout/index.html#use-autoconnect-and-infer-constraints

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