菜单按钮有效，软按钮无效。基本相同的代码

Question

标题说明了一切，我是 SQL 新手，并试图更改用户所做的选择，但在屏幕上放置按钮而不使用 MENU 按钮。似乎按钮没有实例化，但代码看起来对我来说是正确的......我错过了什么？？

package com.example.worldcountriesbooks;

import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class ViewCountry extends Activity implements OnClickListener{


   private long rowID;
   private TextView nameTv;
   private TextView capTv;
   private TextView codeTv; 
   private TextView newEt;




   @Override
   public void onCreate(Bundle savedInstanceState) 
   {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.view_country);
      Button a = (Button)findViewById(R.id.editbutton);
       Button b = (Button)findViewById(R.id.deletebutton);
      a.setOnClickListener(this);
      b.setOnClickListener(this); //Set them up right here...

      setUpViews();
      Bundle extras = getIntent().getExtras();
      rowID = extras.getLong(CountryList.ROW_ID); 
   }

   private void setUpViews() {
       nameTv = (TextView) findViewById(R.id.nameText);
       capTv = (TextView) findViewById(R.id.capText);
       codeTv = (TextView) findViewById(R.id.codeText);
       newEt = (TextView)findViewById(R.id.newText);

   }

   @Override
   protected void onResume()
   {
      super.onResume();
      new LoadContacts().execute(rowID);
   } 

   private class LoadContacts extends AsyncTask<Long, Object, Cursor> 
   {
      DatabaseConnector dbConnector = new DatabaseConnector(ViewCountry.this);

      @Override
      protected Cursor doInBackground(Long... params)
      {
         dbConnector.open();
         return dbConnector.getOneContact(params[0]);
      } 

      @Override
      protected void onPostExecute(Cursor result)
      {
         super.onPostExecute(result);

         result.moveToFirst();
         // get the column index for each data item
         int nameIndex = result.getColumnIndex("name");
         int capIndex = result.getColumnIndex("cap");
         int codeIndex = result.getColumnIndex("code");
         int newIndex = result.getColumnIndex("newb");


         nameTv.setText(result.getString(nameIndex));
         capTv.setText(result.getString(capIndex));
         codeTv.setText(result.getString(codeIndex));
         newEt.setText(result.getString(newIndex));


         result.close();
         dbConnector.close();
      }
   } 


   @Override
   public boolean onCreateOptionsMenu(Menu menu) 
   {
      super.onCreateOptionsMenu(menu);
      MenuInflater inflater = getMenuInflater();
      inflater.inflate(R.menu.view_country_menu, menu);
      return true;
   }


   @Override
   public boolean onOptionsItemSelected(MenuItem item) 
   {
      switch (item.getItemId())
      {
         case R.id.editItem:
            Intent addEditContact =
               new Intent(this, AddEditCountry.class);

            addEditContact.putExtra(CountryList.ROW_ID, rowID);
            addEditContact.putExtra("name", nameTv.getText());
            addEditContact.putExtra("cap", capTv.getText());
            addEditContact.putExtra("code", codeTv.getText());
            addEditContact.putExtra("newb", newEt.getText());

            startActivity(addEditContact); 
            return true;

         case R.id.deleteItem:
            deleteContact();
            return true;

         default:
            return super.onOptionsItemSelected(item);
      } 
   }
   private void deleteContact()
   {

      AlertDialog.Builder alert = new AlertDialog.Builder(ViewCountry.this);

      alert.setTitle(R.string.confirmTitle); 
      alert.setMessage(R.string.confirmMessage); 

      alert.setPositiveButton(R.string.delete_btn,
         new DialogInterface.OnClickListener()
         {
            public void onClick(DialogInterface dialog, int button)
            {
               final DatabaseConnector dbConnector = 
                  new DatabaseConnector(ViewCountry.this);

               AsyncTask<Long, Object, Object> deleteTask =
                  new AsyncTask<Long, Object, Object>()
                  {
                     @Override
                     protected Object doInBackground(Long... params)
                     {
                        dbConnector.deleteContact(params[0]); 
                        return null;
                     } 

                     @Override
                     protected void onPostExecute(Object result)
                     {
                        finish(); 
                     }
                  };

               deleteTask.execute(new Long[] { rowID });               
            }
         }
      );

      alert.setNegativeButton(R.string.cancel_btn, null).show();
   }

public void onClick(View arg0) {
     switch (arg0.getId())
      {
         case R.id.editItem:
            Intent addEditContact =
               new Intent(this, AddEditCountry.class);

            addEditContact.putExtra(CountryList.ROW_ID, rowID);
            addEditContact.putExtra("name", nameTv.getText());
            addEditContact.putExtra("cap", capTv.getText());
            addEditContact.putExtra("code", codeTv.getText());
            addEditContact.putExtra("newb", newEt.getText());

                startActivity(addEditContact); 
                break;

             case R.id.deleteItem:
                deleteContact();
                break;//finish them up here and they do nothing...

    }
    }
}

现在菜单按钮很好用，所以不知道是怎么回事...感谢您的关注

Answer 1

菜单按钮很好用，因为它的 switch 语句是正确的。

但是，您的 onClick 无法正常工作。这是因为案例是针对 不同 id 的，而不是按钮提供的。你想要 R.id.editbutton 和 R.id.deletebutton 代替。

你的方法应该是这样的：

public void onClick(View arg0) {
     switch (arg0.getId())
      {
         case R.id.editbutton: //updated
            Intent addEditContact =
               new Intent(this, AddEditCountry.class);

            addEditContact.putExtra(CountryList.ROW_ID, rowID);
            addEditContact.putExtra("name", nameTv.getText());
            addEditContact.putExtra("cap", capTv.getText());
            addEditContact.putExtra("code", codeTv.getText());
            addEditContact.putExtra("newb", newEt.getText());

                startActivity(addEditContact); 
                break;

             case R.id.deletebutton: //updated
                deleteContact();
                break;

    }
    }
}