android app message,java - How to print message in an Android App

一位初学者在尝试编写第一个Android应用时遇到了问题。尽管教程指示更改字符串资源文件中的'HelloWorld'消息，但在他的项目中并没有找到这个预设的'HelloWorld'字符串。即使手动添加了'HelloWorld'，应用仍然显示默认的'HelloWorld'而不是自定义消息。问题似乎出现在实际设备上运行应用时，内容_main.xml的文本视图部分没有显示修改后的字符串。

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Hi I'm starting to learn how to write Android Apps for the first time but I'm running into problems.

When I go to the string.xml file to enter a message to be printed on the screen. Instead of printing my message it prints "Hello World." It should also be noted that I'm following this tutorial:

And in their tutorial there is a statement that says to change a hello world string to my own custom message. Problem is when I opened the file there was no hello world string. (But the app prints hello world anyway.) And when I go out of my way to make a hello world statement per the example.

Before I modified the file:

OMG Android

Settings

After I modified the file:

OMG Android

Settings

Dpolaristar is programming in Android

The app prints Hello World without the personal message anyway. I'm confused, can anyone tell me if there is some sort of automatic override or somewhere else in the project where it says give the ability to print Hello World that I can override. I already looked but I can't find anything.

My problem also seems to be oddly specific which makes me think I either touched something I shouldn't have or maybe I'm using a different version of Android Studios then the author of the tutorial.

Help?

EDIT:

I managed to get to the text view of the activity_main.xml to add the reference. Problem is there is no textview section to add under.

Here is a copy and paste of the file which I DID NOT change for reference:

xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:app="http://schemas.android.com/apk/res-auto"

xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"

android:layout_height="match_parent" android:fitsSystemWindows="true"

tools:context=".MainActivity">

android:layout_width="match_parent"

android:theme="@style/AppTheme.AppBarOverlay">

android:layout_width="match_parent" android:layout_height="?attr/actionBarSize"

android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" />

android:layout_width="wrap_content" android:layout_height="wrap_content"

android:layout_gravity="bottom|end" android:layout_margin="@dimen/fab_margin"

android:src="@android:drawable/ic_dialog_email" />

EDIT 2:I've looked around my project and have found that in the DESIGN view of the content_main.xml I does show the value for the string I typed just not when I run the app ON MY TABLET!

Does this give anyone any clues?