Question

我需要使用AsyncTask在我的应用程序中执行数据库更新（主要是添加和删除）。我不知道在我的程序中为该函数编码究竟是什么。它将进入我的第二个活动文件。

DatabaseActivity.java

package com.example.healthylife;



import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;


public class DatabaseActivity extends AppCompatActivity {


TextView idView;
EditText RecipeBox;
EditText CategoryBox;
EditText IngredientsBox;
EditText InstructionsBox;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_database);

    idView = (TextView) findViewById(R.id.Recipe_ID);
    RecipeBox = (EditText) findViewById(R.id.edit_RecipeName);
    CategoryBox = (EditText) findViewById(R.id.input_category);
    IngredientsBox = (EditText) findViewById(R.id.edit_Ingredients);
    InstructionsBox = (EditText) findViewById(R.id.edit_Instructions);
}

public void newRecipe (View view){
    MyDBHandler dbHandler = new MyDBHandler (this, null, null, 1);

    Recipe recipe = new Recipe();

    dbHandler.addRecipe(recipe);
    RecipeBox.setText("");
    CategoryBox.setText("");
    IngredientsBox.setText("");
    InstructionsBox.setText("");
}

public void lookupRecipe (View view){
    MyDBHandler dbHandler = new MyDBHandler(this, null, null, 1);

    Recipe recipe = dbHandler.findRecipe(RecipeBox.getText().toString());

    if (recipe != null){
        idView.setText(String.valueOf(recipe.getID()));

        CategoryBox.setText(String.valueOf(recipe.getCategory()));
        IngredientsBox.setText(String.valueOf(recipe.getIngredients()));
        InstructionsBox.setText(String.valueOf(recipe.getInstructions()));
    }else {
        idView.setText("No Match Found");
    }
}

public void removeRecipe (View view){
    MyDBHandler dbHandler = new MyDBHandler(this, null, null, 1);

    boolean result = dbHandler.deleteRecipe(RecipeBox.getText().toString());

    if (result){
        idView.setText("Record Deleted");
        RecipeBox.setText("");
        CategoryBox.setText("");
        IngredientsBox.setText("");
        InstructionsBox.setText("");
    }else
        idView.setText("No Match Found");
}

}

任何帮助将不胜感激。感谢。

Answer 1

你的问题很广泛。我想，你不需要额外的Activity来执行该操作。

使用构造函数在同一活动中创建异步任务，该构造函数使用数据库连接处理程序，要更新的数据以及指示其更新或删除操作的标志。您的活动中将有一些回调功能（例如，当用户按下＆＃34;保存＆＃34;或＆＃34;删除＆＃34;）时。在此触发器上，使用相应的值启动异步任务。

在asynctask类中，分别执行上面编码的操作。

您可以为每个操作编写单独的异步任务！这取决于你的设计！

private class AsyncTaskSaveDelete extends AsyncTask<Void, Void, boolean> {
    private DBHandler handler;
    private Recipe recipe;
    private boolean isDelete;

    public AsyncTaskSaveDelete(DBHandler handler,Recipe recipe,boolean isDelete ){
        this.handler = handler;
        this.recipe = recipe;
        this.isDelete = isDelete;
    }

     protected Long doInBackground( {
         if(isDelete){
            return dbHandler.deleteRecipe(recipe);
         }else{
          return dbHandler.addRecipe(recipe);
         }
     }

     protected void onPostExecute(boolean result) {
         runOnUiThread(new PostRunnable(){
            //update the UI
         })
     }
 }


public void newRecipe (View view){
...
    new AsyncTaskSaveDelete(handler,recipe,false).execute();
...
}

在SQLite数据库中使用AsyncTask

1 个答案: