将数据从数据库显示到 listView Android

Question

我正在尝试将数据库中的所有数据显示到列表视图中

创建数据库的代码：

DataHander.java

package com.example.testingforstack;

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

public class DataHandler {
    public static final String NAME = "name";
    public static final String EMAIL = "email";
    public static final String TABLE_NAME = "mytable";
    public static final String DATA_BASE_NAME = "mydatabase";
    public static final int DATABASE_VERSION = 1;
    public static final String TABLE_CREATE = "create table mytable (name text not null, email text not null);";

    DataBaseHelper dbhelper;
    Context ctx;
    SQLiteDatabase db;

    public DataHandler(Context ctx){
        this.ctx = ctx;
        dbhelper = new DataBaseHelper(ctx);
    }

    public static class DataBaseHelper extends SQLiteOpenHelper{

        public DataBaseHelper(Context ctx) {
            super(ctx, DATA_BASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db){
            try{
                db.execSQL(TABLE_CREATE);
            }catch (SQLException e){
                e.printStackTrace();
            }
        }

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

    public DataHandler open(){
        db = dbhelper.getReadableDatabase();
        return this;
    }

    public void close(){
        dbhelper.close();
    }

    public long insertData(String name, String email){
        ContentValues content = new ContentValues();
        content.put(NAME, name);
        content.put(EMAIL, email);
        return db.insertOrThrow(TABLE_NAME, null, content);
    }

    public Cursor returnData(){
        return db.query(TABLE_NAME, new String[] {NAME, EMAIL}, null, null, null, null, null); 
    }

}

mainActivity.java

package com.example.testingforstack;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.database.Cursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    Button save, load;
    EditText name, email;
    DataHandler handler;
    String getName, getEmail;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        save = (Button) findViewById(R.id.save);
        load = (Button) findViewById(R.id.load);
        name = (EditText) findViewById(R.id.name);
        email = (EditText) findViewById(R.id.email);

        save.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String getName = name.getText().toString();
                String getEmail = email.getText().toString();

                handler = new DataHandler(getBaseContext());
                handler.open();
                long id = handler.insertData(getName, getEmail);
                insertSuccess();
                //Toast.makeText(getBaseContext(), "Data inserted", Toast.LENGTH_LONG).show();
                handler.close();
            }
        });

        load.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                getName = "";
                getEmail = "";
                handler = new DataHandler(getBaseContext());
                handler.open();
                Cursor C = handler.returnData();
                if(C.moveToFirst()){
                    do{
                        getName = C.getString(0);
                        getEmail = C.getString(1);
                    }while(C.moveToNext());
                }
                handler.close();
                loadSuccess();
                //Toast.makeText(getBaseContext(), "Name: "+getName+", Email: "+getEmail, Toast.LENGTH_LONG).show();
            }
        });
    }

    public void insertSuccess()
    {
        AlertDialog.Builder insertData = new AlertDialog.Builder(this);

        insertData.setTitle("Info");
        insertData.setMessage("Data Inserted");
        insertData.setNegativeButton("OK", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface arg0, int value) {
                // TODO Auto-generated method stub
                arg0.dismiss();
            }
        });
        insertData.show();
    }

    public void loadSuccess()
    {
        AlertDialog.Builder loadData = new AlertDialog.Builder(this);

        loadData.setTitle("Info");
        loadData.setMessage("Name: "+getName+" & your email: "+getEmail);
        loadData.setNegativeButton("OK", new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface arg0, int value) {
                // TODO Auto-generated method stub
                arg0.dismiss();
            }
        });
        loadData.show();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

我有两个按钮 save 和 load。我已经成功实现了保存按钮来保存用户名和电子邮件。但是，我真的不知道将数据加载到列表视图中。该怎么做？

Answer 1

在列表视图中，您可以使用不同类型的适配器。对于数据库，最合适的是在您告诉使用哪个游标的地方使用 cursorAdapter。您还可以手动遍历 DB 中的元素并将它们保存在数组中的其他对象中，然后您可以使用 arrayAddapter 在其中传递对象数组。在每种情况下，您都必须设置 binder 或覆盖方法 onCreateView，您可以在其中告诉哪个参数进入哪个子项。

您可以查看此http://www.mysamplecode.com/2012/07/android-listview-cursoradapter-sqlite.html 示例以获取更多信息。