MainActivity

Hier wird jetzt alles zusammen gebraucht.

Beispiel:

import androidx.appcompat.app.AppCompatActivity;  
import androidx.lifecycle.Observer;  
import androidx.lifecycle.ViewModelProvider;  
import androidx.recyclerview.widget.LinearLayoutManager;  
import androidx.recyclerview.widget.RecyclerView;  
  
import android.os.Bundle;  
import android.view.View;  
import android.widget.EditText;  
  
import java.util.List;  
import java.util.Locale;  
  
public class MainActivity extends AppCompatActivity {  
    private MainViewModel mViewModel;  
    private ArticleListAdapter adapter;  
  
    //Views
    private EditText articleNr;  
    private EditText articleName;  
    private EditText articleQuantity;  
  
    //Recycler
    RecyclerView articleList;  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        articleNr = findViewById(R.id.inputArticleNr);  
        articleName = findViewById(R.id.inputArticleName);  
        articleQuantity = findViewById(R.id.inputArticleQuantity);  
        //register Observer  
        //mViewModel = new ViewModelProvider(this).get(MainViewModel.class);        mViewModel = new MainViewModel(getApplication());  
        mViewModel.getAllArticles().observe(this, articles -> {  
            adapter.setArticleList(articles);  
            System.out.println(articles.toString());  
        });  
        mViewModel.getSearchResults().observe(this,articles -> {  
            if (articles.size() > 0)  {  
                articleNr.setText(String.format(Locale.GERMAN, "%d", articles.get(0).getId()));  
                articleName.setText(articles.get(0).getName());  
                articleQuantity.setText(String.format( Locale.GERMAN, "%d", articles.get(0).getQuantity()));  
            } else {  
                articleNr.setText("kein Treffer");  
            }  
        });
        //Build-up Recycler View  
        articleList = findViewById(R.id.articleList);  
        articleList.setLayoutManager(new LinearLayoutManager(getApplicationContext()));  
        adapter = new ArticleListAdapter(R.layout.article_list_item);  
        articleList.setAdapter(adapter);  
    }  
  
    public void addArticle(View v) {  
        String name = articleName.getText().toString();  
        String quantity = articleQuantity.getText().toString();  
        
        if (!name.equals("") && !quantity.equals("")) {  
            Article article = new Article(name, Integer.parseInt(quantity));  
            mViewModel.insertArticle(article);  
            clearFields();  
        } else {  
            articleNr.setText("Unvollständige Information");  
        }  
    }  
 
    public void findArticles(View view) {  
        mViewModel.findArticle(articleName.getText().toString());  
    }  
  
    public void deleteArticle(View view) {  
        mViewModel.deleteArticle(articleName.getText().toString());  
        clearFields();  
    }  
  
    public void clearFields() {  
        articleNr.setText("");  
        articleName.setText("");  
        articleQuantity.setText("");  
    }  
  
}