Android Studio初学者教程问题(Android Studio Beginner Tutorial issues)

我是编程新手，刚下载Android Studio。我试图按照教程创建第一个程序，他们告诉我要对activity_my.xml文件进行更改，但是当我执行该程序时，MyActivity.java文件中存在大量错误。它告诉我用一个名为content_my.xml的文件替换它。当我对content_my.xml文件进行所有更改并运行模拟器时，没有任何更改，我继续获得相同的布局，这似乎是由activity_my.xml代码确定的。我所指的说明位于http://developer.android.com/training/basics/firstapp/building-ui.html任何帮助将不胜感激！

activiy_my.xml的原始代码：

<?xml version="1.0" encoding="utf-8"?> <android.support.design.widget.CoordinatorLayout 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=".MyActivity"> <android.support.design.widget.AppBarLayout android:layout_height="wrap_content" android:layout_width="match_parent" android:theme="@style/AppTheme.AppBarOverlay"> <android.support.v7.widget.Toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionBarSize" android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay" /> </android.support.design.widget.AppBarLayout> <include layout="@layout/content_my" /> <android.support.design.widget.FloatingActionButton android:id="@+id/fab" 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" /> </android.support.design.widget.CoordinatorLayout>

他们希望我输入的代码：

错误：（18，54）错误：找不到符号变量工具栏错误：（21,76）错误：找不到符号变量fab错误：执行任务失败'：app：compileDebugJavaWithJavac' 。

编译失败; 详细信息请参阅编译器错误输出。

错误是指MyActivity.java文件中的代码，它是：

public class MyActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_my); Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); setSupportActionBar(toolbar); FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); fab.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) .setAction("Action", null).show(); } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.menu_my, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); //noinspection SimplifiableIfStatement if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } }

I am new to programming and just downloaded Android Studio. I am trying to follow the tutorial in creating the first program and they tell me to make changes to the activity_my.xml file but when I do the the program has a huge amount of errors in the MyActivity.java file. It tells me to replace with but that exists in a file called content_my.xml. When I make all of the changes to the content_my.xml file and i run the emulator nothing changes and I keep getting the same layout which seems to be determined by the activity_my.xml code. The instructions I am referring to are located at http://developer.android.com/training/basics/firstapp/building-ui.html Any help would be appreciated!

The original code for the activiy_my.xml:

The code they want me to input:

The error I get when I replace the code: Error:(18, 54) error: cannot find symbol variable toolbar Error:(21, 76) error: cannot find symbol variable fab Error:Execution failed for task ':app:compileDebugJavaWithJavac'.