diff --git a/app/src/androidTest/java/cc/niushuai/didicheck/ExampleInstrumentedTest.java b/app/src/androidTest/java/cc/niushuai/didicheck/ExampleInstrumentedTest.java
index ecc302b..75b6423 100644
--- a/app/src/androidTest/java/cc/niushuai/didicheck/ExampleInstrumentedTest.java
+++ b/app/src/androidTest/java/cc/niushuai/didicheck/ExampleInstrumentedTest.java
@@ -1,15 +1,15 @@
 package cc.niushuai.didicheck;
 
+import static org.junit.Assert.assertEquals;
+
 import android.content.Context;
 
-import androidx.test.platform.app.InstrumentationRegistry;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.platform.app.InstrumentationRegistry;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
-import static org.junit.Assert.*;
-
 /**
  * Instrumented test, which will execute on an Android device.
  *
diff --git a/app/src/main/java/cc/niushuai/didicheck/MainActivity.java b/app/src/main/java/cc/niushuai/didicheck/MainActivity.java
index 4edb906..fe71e3b 100644
--- a/app/src/main/java/cc/niushuai/didicheck/MainActivity.java
+++ b/app/src/main/java/cc/niushuai/didicheck/MainActivity.java
@@ -1,22 +1,16 @@
 package cc.niushuai.didicheck;
 
 import android.os.Bundle;
+import android.view.View;
 
-import com.google.android.material.floatingactionbutton.FloatingActionButton;
-import com.google.android.material.snackbar.Snackbar;
-import com.google.android.material.tabs.TabLayout;
-
-import androidx.viewpager.widget.ViewPager;
 import androidx.appcompat.app.AppCompatActivity;
-import androidx.viewpager2.widget.ViewPager2;
+import androidx.viewpager.widget.ViewPager;
 
-import android.view.Menu;
-import android.view.MenuItem;
-import android.view.View;
+import com.google.android.material.floatingactionbutton.FloatingActionButton;
+import com.google.android.material.snackbar.Snackbar;
 
-import cc.niushuai.didicheck.ui.main.HomePagerAdapter;
-import cc.niushuai.didicheck.ui.main.SectionsPagerAdapter;
 import cc.niushuai.didicheck.databinding.ActivityMainBinding;
+import cc.niushuai.didicheck.ui.main.SectionsPagerAdapter;
 
 public class MainActivity extends AppCompatActivity {
 
diff --git a/app/src/main/java/cc/niushuai/didicheck/ui/main/PageViewModel.java b/app/src/main/java/cc/niushuai/didicheck/ui/main/PageViewModel.java
index 14b3984..4829bac 100644
--- a/app/src/main/java/cc/niushuai/didicheck/ui/main/PageViewModel.java
+++ b/app/src/main/java/cc/niushuai/didicheck/ui/main/PageViewModel.java
@@ -2,7 +2,6 @@ package cc.niushuai.didicheck.ui.main;
 
 import static androidx.lifecycle.Transformations.map;
 
-import androidx.arch.core.util.Function;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
diff --git a/app/src/main/java/cc/niushuai/didicheck/ui/main/PlaceholderFragment.java b/app/src/main/java/cc/niushuai/didicheck/ui/main/PlaceholderFragment.java
index c90515b..15f68c8 100644
--- a/app/src/main/java/cc/niushuai/didicheck/ui/main/PlaceholderFragment.java
+++ b/app/src/main/java/cc/niushuai/didicheck/ui/main/PlaceholderFragment.java
@@ -7,15 +7,14 @@ import android.view.ViewGroup;
 import android.widget.CalendarView;
 import android.widget.TextView;
 
-import androidx.annotation.Nullable;
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProvider;
 
 import java.util.Date;
 
-import cc.niushuai.didicheck.R;
 import cc.niushuai.didicheck.databinding.FragmentMainBinding;
 
 /**
diff --git a/app/src/test/java/cc/niushuai/didicheck/ExampleUnitTest.java b/app/src/test/java/cc/niushuai/didicheck/ExampleUnitTest.java
index d85be6a..a529fa8 100644
--- a/app/src/test/java/cc/niushuai/didicheck/ExampleUnitTest.java
+++ b/app/src/test/java/cc/niushuai/didicheck/ExampleUnitTest.java
@@ -1,8 +1,8 @@
 package cc.niushuai.didicheck;
 
-import org.junit.Test;
+import static org.junit.Assert.assertEquals;
 
-import static org.junit.Assert.*;
+import org.junit.Test;
 
 /**
  * Example local unit test, which will execute on the development machine (host).