R file in android

Question

Why R file does not generate in android studio? There's no any error in xml file. When I build the project it gives error message as below.

Error:(2) Error retrieving parent for item: No resource found that matches the given name 'android:TextAppearance.Material.Widget.Button.Inverse'. Error:(2) Error retrieving parent for item: No resource found that matches the given name 'android:Widget.Material.Button.Colored'.

Error:Execution failed for task ':app:processDebugResources'. com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command 'C:\Users\admin_2\AppData\Local\Android\Sdk\build-tools\22.0.1\aapt.exe'' finished with non-zero exit value 1

Code

public class MainActivity extends Activity {
int counter;
Button add,sub;
TextView display;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    counter = 0;
    add = (Button)findViewById(R.id.bAdd);
    sub = (Button)findViewById(R.id.bSub);
    display = (TextView)findViewById(R.id.TvDisplay);

    add.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            counter++;
            display.setText("Your total is" + counter);

        }

    });

    sub.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            counter--;
            display.setText("Your total is" + counter);

        }

    });

}

@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_main, 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
    int id = item.getItemId();

    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

View Layout

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    >

    <TextView
        android:layout_height="wrap_content"
        android:layout_width="396dp"
        android:text="your total is 0"
        android:textSize="80px"
        android:layout_gravity="center_horizontal"
        android:gravity="center"
        android:id="@+id/TvDisplay"/>


    <Button android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:text="add_one"
        android:textSize="20dp"
        android:layout_gravity="center_vertical"
        android:gravity="center"
        android:id="@+id/bAdd"
        />

    <Button android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:text="subtract_one"
        android:textSize="20dp"
        android:gravity="center"
        android:id="@+id/bSub"
        />


</LinearLayout>

Manifest file

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.admin_2.myapplication" >

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

Exactly as it sounds, R.java will not be generated if you have an error inside your xml.

The reason you have an error is because your syntax for how you're referring to that style is wrong.

It should be:

@android:style/<name>