// MainActivity.java
import android.support.v7.app.ActionBarActivity;// error

public class MainActivity extends ActionBarActivity {...} // error

// DisplayMessageActivity.java
import android.support.v4.app.NavUtils; // error on this line
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.display_message, menu);// error at R
    return true;
}

public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case android.R.id.home:
        // This ID represents the Home or Up button. In the case of this
        // activity, the Up button is shown. Use NavUtils to allow users
        // to navigate up one level in the application structure. For
        // more details, see the Navigation pattern on Android Design:
        //
        // http://developer.android.com/design/patterns/navigation.html#up-vs-back
        //
        NavUtils.navigateUpFromSameTask(this);// error at NavUtils
        return true;
    }
    return super.onOptionsItemSelected(item);
}

The import android.support cannot be resolved   MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 4  Java Problem
The method onCreate(Bundle) of type MainActivity must override or implement a supertype method  MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 16 Java Problem
ActionBarActivity cannot be resolved to a type  MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 12 Java Problem
R cannot be resolved to a variable  MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 18 Java Problem
ActionBarActivity cannot be resolved to a type  MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 17 Java Problem
The method onCreateOptionsMenu(Menu) of type MainActivity must override or implement a supertype method MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 23 Java Problem
The import android.support cannot be resolved   DisplayMessageActivity.java /MyFirstApp/src/com/example/myfirstapp  line 9  Java Problem
R cannot be resolved to a variable  DisplayMessageActivity.java /MyFirstApp/src/com/example/myfirstapp  line 51 Java Problem
The method getMenuInflater() is undefined for the type MainActivity MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 25 Java Problem
R cannot be resolved to a variable  MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 25 Java Problem
The constructor Intent(MainActivity, Class<DisplayMessageActivity>) is undefined    MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 30 Java Problem
R cannot be resolved to a variable  MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 31 Java Problem
The method startActivity(Intent) is undefined for the type MainActivity MainActivity.java   /MyFirstApp/src/com/example/myfirstapp  line 34 Java Problem
Jar mismatch! Fix your dependencies MyFirstApp      Unknown Android Dependency Problem
NavUtils cannot be resolved DisplayMessageActivity.java /MyFirstApp/src/com/example/myfirstapp  line 66 Java Problem

[2014-01-23 18:31:52 - MyFirstApp] Found 2 versions of android-support-v4.jar in the    dependency list,
[2014-01-23 18:31:52 - MyFirstApp] but not all the versions are identical (check is based on SHA-1 only at this time).
[2014-01-23 18:31:52 - MyFirstApp] All versions of the libraries must be the same at this time.
[2014-01-23 18:31:52 - MyFirstApp] Versions found are:
[2014-01-23 18:31:52 - MyFirstApp] Path: C:UsersdaiyueGoogle DriveMyFirstApplibsandroid-support-v4.jar
[2014-01-23 18:31:52 - MyFirstApp]  Length: 621451
[2014-01-23 18:31:52 - MyFirstApp]  SHA-1: 5896b0a4e377ac4242eb2bc785220c1c4fc052f4
[2014-01-23 18:31:52 - MyFirstApp] Path: C:Program Files (x86)Androidandroid-sdkextrasandroidsupportv7appcompatlibsandroid-support-v4.jar
[2014-01-23 18:31:52 - MyFirstApp]  Length: 627582
[2014-01-23 18:31:52 - MyFirstApp]  SHA-1: db0f122c99ef9f90dbab3fada6d191f2880cbb8e
[2014-01-23 18:31:52 - MyFirstApp] Jar mismatch! Fix your dependencies
[2014-01-23 18:31:53 - MyFirstApp] W/ResourceType( 8160): ResXMLTree_node header size 0 is too small.
[2014-01-23 18:31:53 - MyFirstApp] C:UsersdaiyueGoogle DriveMyFirstAppresvaluesdesktop.ini:1: error: Error parsing XML: syntax error
[2014-01-23 18:31:53 - MyFirstApp] C:UsersdaiyueGoogle DriveMyFirstAppresvalues-v11desktop.ini:1: error: Error parsing XML: syntax error
[2014-01-23 18:31:53 - MyFirstApp] C:UsersdaiyueGoogle DriveMyFirstAppresvalues-v14desktop.ini:1: error: Error parsing XML: syntax error
[2014-01-23 18:31:53 - MyFirstApp] C:UsersdaiyueGoogle DriveMyFirstAppresvalues-sw600dpdesktop.ini:1: error: Error parsing XML: syntax error
[2014-01-23 18:31:53 - MyFirstApp] C:UsersdaiyueGoogle DriveMyFirstAppresvalues-sw720dp-landdesktop.ini:1: error: Error parsing XML: syntax error
[2014-01-23 18:31:53 - MyFirstApp] C:UsersdaiyueGoogle DriveMyFirstAppreslayoutdesktop.ini:1: error: Error parsing XML: syntax error
[2014-01-23 18:31:53 - MyFirstApp] C:UsersdaiyueGoogle DriveMyFirstAppresmenudesktop.ini:1: error: Error parsing XML: syntax error