Cleared crashing bug ( it was due to not doing a null check in the observe function of CounterViewModel.java )..

Also cleared a major bug that was causing the to not respond to the button clicks ( it was actually because of using update query instead of insert query in the CountDao.java class of ROOM database so it tried to update a value that was not yet created.

 Thanks to harish for bringing out these bugs.. ;)  )

Author: kpk88078

app/src/main/java/com/geeks4ever/counter_app/model/CountModel.java

@@ -1,8 +1,5 @@
 package com.geeks4ever.counter_app.model;
 
-import android.util.Log;
-
-import androidx.lifecycle.LiveData;
 import androidx.room.ColumnInfo;
 import androidx.room.Entity;
 import androidx.room.PrimaryKey;
@@ -24,7 +21,4 @@ public CountModel(int key, String count){
     public String getCount(){
         return this.count;
     }
-
-    public void setCount(String count){
-        this.count = count;}
 }

app/src/main/java/com/geeks4ever/counter_app/model/repository/CountDao.java

@@ -4,19 +4,20 @@
 import androidx.room.Dao;
 import androidx.room.Insert;
 import androidx.room.Query;
-import androidx.room.Update;
 
 import com.geeks4ever.counter_app.model.CountModel;
 
 import java.util.List;
 
+import static androidx.room.OnConflictStrategy.REPLACE;
+
 @Dao
 public interface CountDao {
 
     @Query("Select * from countmodel where `key`= 0")
     LiveData<List<CountModel>> getCount();
 
-    @Update
+    @Insert(onConflict = REPLACE)
     void setCount(CountModel count);
 
 }

app/src/main/java/com/geeks4ever/counter_app/model/repository/CountDatabase.java

@@ -1,16 +1,13 @@
 package com.geeks4ever.counter_app.model.repository;
 
 import android.content.Context;
-import android.util.Log;
 
 import androidx.room.Database;
 import androidx.room.Room;
 import androidx.room.RoomDatabase;
 
 import com.geeks4ever.counter_app.model.CountModel;
 
-import java.util.concurrent.Executors;
-
 @Database(entities = {CountModel.class}, version = 1, exportSchema = false)
 public abstract class CountDatabase extends RoomDatabase {
 

app/src/main/java/com/geeks4ever/counter_app/viewmodel/CounterViewModel.java

@@ -1,17 +1,14 @@
 package com.geeks4ever.counter_app.viewmodel;
 
 import android.app.Application;
-import android.content.Context;
 
 import androidx.annotation.NonNull;
 import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.Observer;
-import androidx.lifecycle.ViewModel;
 
 import com.geeks4ever.counter_app.model.CountModel;
-import com.geeks4ever.counter_app.model.repository.CountDatabase;
 import com.geeks4ever.counter_app.model.repository.CountRepository;
 
 import java.util.List;
@@ -36,7 +33,8 @@ public CounterViewModel(@NonNull Application application) {
         countRepository.getCount().observeForever( new Observer<List<CountModel>>() {
             @Override
             public void onChanged(List<CountModel> countModel) {
-                count.setValue(countModel.get(0).getCount());
+                if(!countModel.isEmpty())
+                    count.setValue(countModel.get(0).getCount());
             }
         });
     }

build.gradle

@@ -5,7 +5,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath "com.android.tools.build:gradle:4.1.0"
+        classpath 'com.android.tools.build:gradle:4.1.2'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files