Android studio 如何从 SQLite 中获取数据并将其放在 EditText 上

Question

我是编码初学者，我真的希望你能帮助我。 所以我的问题是我创建了一个 SQLite 数据库，并将编辑文本中的信息保存到 ListView 但现在我希望当我点击列表上的特定项目时，它将打开 EditList 活动，其中包含用户输入的所有信息并保存在那里，请帮助我，这是我的代码（我已经检查了所有信息是否已保存我只想知道在单击列表上的项目时对其进行编辑）：

这是我的数据库助手：

 package com.example.lian.atlist;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

/**
 * Created by Lian on 18-Sep-18.
 */

public class DataBaseHelper extends SQLiteOpenHelper {
    public static final String DATABASE_NAME = "List.db";
    public static final String TABLE_NAME = "Notes_table";
    public static final String ID = "ID";
    public static final String TITLE = "TITLE";
    public static final String DESCRIPTION = "DESCRIPTION";

    public DataBaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    //    SQLiteDatabase db = this.getWritableDatabase();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    db.execSQL("create table " + TABLE_NAME +" (ID INTEGER PRIMARY KEY AUTOINCREMENT,TITLE TEXT,DESCRIPTION TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
    onCreate(db);
    }

    public boolean insertData(String title,String description){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues= new ContentValues();
        contentValues.put(TITLE,title);
        contentValues.put(DESCRIPTION,description);
        long result =db.insert(TABLE_NAME,null,contentValues);
        if(result==-1){
            return false;
        }else
        return true;
    }
    public Cursor getAllData(){
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor res = db.rawQuery("select * from " +TABLE_NAME,null);
        return  res;
    }
    public boolean updateData(String id,String title,String description){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues= new ContentValues();
        contentValues.put(ID,id);
        contentValues.put(TITLE,title);
        contentValues.put(DESCRIPTION,description);
        db.update(TABLE_NAME,contentValues,"ID = ?",new String[]{id});
        return true;
    }
}

这是我的主要活动：

package com.example.lian.atlist;

import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.os.Debug;
import android.os.Parcelable;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.EventLogTags;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ExpandableListView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.io.Serializable;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.List;

import static com.example.lian.atlist.EditList.Description;
import static com.example.lian.atlist.EditList.Title;
import static com.example.lian.atlist.EditList.id;
public class MainActivity extends AppCompatActivity {

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

        myDB= new DataBaseHelper(this);
        ListView listView =(ListView)  findViewById(R.id.LV);
        ArrayList<String> TheList = new ArrayList<>();
        final Cursor data =myDB.getAllData();
        ListAdapter listAdapter = new ArrayAdapter<>(this,android.R.layout.simple_list_item_1,TheList);
        listView.setAdapter(listAdapter);

       listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override

        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

          Intent EditNote = new Intent(MainActivity.this, EditList.class);
         startActivity(EditNote);
                                           }
       });

        if (data.getCount()==0){
            Toast.makeText(MainActivity.this, "The list is empty", Toast.LENGTH_LONG).show();
        }else{
            while(data.moveToNext()){
                TheList.add(data.getString(1));


            }
        }

        Intent SaveNote = getIntent();

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

               Intent addNote = new Intent(MainActivity.this, EditList.class);
               startActivity(addNote);
            }
        });
    }




}

这是我的 EditList 活动：

package com.example.lian.atlist;

import android.content.Intent;
import android.database.Cursor;
import android.os.Message;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import org.w3c.dom.Text;

import java.security.PublicKey;

public class EditList extends AppCompatActivity {
    static TextView id;
    static EditText Title;
    static EditText Description;
    Button SaveButton;
    DataBaseHelper myDB;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_edit_list);
        myDB = new DataBaseHelper(this);
        id=(TextView)findViewById(R.id.id);
        Title=(EditText)findViewById(R.id.editText);
        Description=(EditText)findViewById(R.id.editText2);
        SaveButton=(Button) findViewById(R.id.SaveButton);
        AddData();
        viewAll();
        UpdateData();

    }
    Intent AddNote = getIntent();
    Intent EditNote = getIntent();



    public void UpdateData(){
        boolean isUpdated = myDB.updateData(id.getText().toString()
                ,Title.getText().toString()
                ,Description.getText().toString());
        if (isUpdated==true){
                Toast.makeText(EditList.this,"Data Updated",Toast.LENGTH_LONG).show();
            }else {
                Toast.makeText(EditList.this, "Data is not Updated", Toast.LENGTH_LONG).show();
            }

        }



    public void viewAll(){
        Cursor res = myDB.getAllData();
        if(res.getCount()==0){
            //show message
            showMessage("Error","Nothing found");
            return;
        }
    }

    public void showMessage(String title,String Message){
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setCancelable(true);
        builder.setTitle(title);
        builder.setMessage(Message);
        builder.show();
    }
        public void AddData(){
        SaveButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

               boolean isInserted= myDB.insertData(Title.getText().toString()
                        ,Description.getText().toString());


                if (isInserted == true){
                    Toast.makeText(EditList.this,"Data Inserted",Toast.LENGTH_LONG).show();
                }else {
                    Toast.makeText(EditList.this, "Data is not Inserted", Toast.LENGTH_LONG).show();
                }
                Intent SaveNote = new Intent(EditList.this, MainActivity.class);
                startActivity(SaveNote);
            }
        });
        }



}

Answer 1

有很多方法可以做到这一点。其中之一是使用附加项传递您单击的元素的 id

Intent i = new Intent(this, EditActivity.class);
i.putExtra("id", id); //Find id using the position in the click listener
startActivity(i);

然后在EditActivity中做

Intent i= getIntent();
int id = i.getIntExtra("id", 0);

获得 id 后，只需进行数据库查询并显示详细信息。