Any Example showing how to login using Facebook SDK 4.0 in Android either by using own button or Facebook Button?

Is there any tutorial or example showing how to login using own Button using Facebook SDK 4.0 in Android? I am not getting anywhere and using facebook developers site it is difficult to understand.Like below when calling FBlogin button I want to check go for login if user has not logged in or if logged in I want the access token to get facebook profile information and user likes.

FBlogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
             //Facebook login Code to get profile info and user likes  
        }
    });

I have tried also loginButton Facebook.

  <com.facebook.login.widget.LoginButton
            android:id="@+id/login_button"
            android:layout_width="244dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:layout_marginTop="30dp"
            android:layout_marginBottom="30dp" 

/>

But it is showing error in xml :-

java.lang.NoClassDefFoundError: Could not initialize class com.facebook.login.widget.LoginButton
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:413)
    at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:105)
    at com.android.tools.idea.rendering.LayoutlibCallback.loadView(LayoutlibCallback.java:176)
    at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:206)
    at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:131)
    at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:739)
    at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:372)
    at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:369)
    at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:326)
    at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:350)
    at com.android.tools.idea.rendering.RenderService$5.compute(RenderService.java:708)
    at com.android.tools.idea.rendering.RenderService$5.compute(RenderService.java:697)
    at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:932)
    at com.android.tools.idea.rendering.RenderService.createRenderSession(RenderService.java:697)
    at com.android.tools.idea.rendering.RenderService.render(RenderService.java:816)
    at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.doRender(AndroidLayoutPreviewToolWindowManager.java:646)
    at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.access$1700(AndroidLayoutPreviewToolWindowManager.java:82)
    at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7$1.run(AndroidLayoutPreviewToolWindowManager.java:589)
    at com.intellij.openapi.progress.impl.ProgressManagerImpl$2.run(ProgressManagerImpl.java:178)
    at com.intellij.openapi.progress.ProgressManager.executeProcessUnderProgress(ProgressManager.java:209)
    at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:212)
    at com.intellij.openapi.progress.impl.ProgressManagerImpl.runProcess(ProgressManagerImpl.java:171)
    at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7.run(AndroidLayoutPreviewToolWindowManager.java:584)
    at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
    at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
    at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
    at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
    at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
    at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
    at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
    at com.intellij.util.Alarm$Request$1.run(Alarm.java:327)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

My Activity class:-

protected void onCreate(Bundle savedInstanceState)  {
        super.onCreate(savedInstanceState);
        FacebookSdk.sdkInitialize(getApplicationContext());
        setContentView(R.layout.activity_main);

Ia there any example/tutorial to login using facebook sdk4.0? I am stuck in both way. Please help.