如何显示来自 sqlite 数据库的所有数据答案

【问题标题】：How to display all data from sqlite database如何显示来自 sqlite 数据库的所有数据
【发布时间】：2015-09-20 17:11:43
【问题描述】：

我正在制作一个应用程序，让用户可以添加他们的学校科目。在我继续之前，让我给你我的代码：

主活动：

    package cannon.gaming.mymarks;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.text.Html;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


public class MainActivity extends ActionBarActivity {
    TextView textSubject;
    String SUBJECT, PASS;
    Context ctx =  this;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getSupportActionBar().hide();
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_main);

        /*Button buttonAdd = (Button) findViewById(R.id.buttonAdd);
        buttonAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(v.getContext(), RegisterActivity.class);
                intent.setFlags(intent.FLAG_ACTIVITY_CLEAR_TOP);
                intent.putExtra("EXIT", true);
                startActivityForResult(intent, 0);
            }
        });*/

        Button buttonAdd = (Button) findViewById(R.id.buttonAdd);
        textSubject = (TextView) findViewById(R.id.textSubject);
        buttonAdd.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                showInputDialog();
            }
        });
    }

    protected void showInputDialog() {

        // get prompts.xml view
        LayoutInflater layoutInflater = LayoutInflater.from(MainActivity.this);
        View promptView = layoutInflater.inflate(R.layout.activity_dialog, null);
        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(MainActivity.this);
        alertDialogBuilder.setView(promptView);

        final EditText editText = (EditText) promptView.findViewById(R.id.edittext);
        // setup a dialog window
        alertDialogBuilder.setCancelable(false)
                .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        SUBJECT = editText.getText().toString();
                        PASS = "0";
                        DatabaseOperations DB = new DatabaseOperations(ctx);
                        DB.putInformation(DB, SUBJECT, PASS);
                        Toast.makeText(getBaseContext(), "Subject added", Toast.LENGTH_SHORT).show();
                        finish();
                    }
                })
                .setNegativeButton("Cancel",
                        new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                dialog.cancel();
                            }
                        });

        // create an alert dialog
        AlertDialog alert = alertDialogBuilder.create();
        alert.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.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

表格数据：

package cannon.gaming.mymarks;

import android.provider.BaseColumns;

/**
 * Created by Asuspc on 01/07/2015.
 */
public class TableData {

    public TableData()
    {

    }

    public static abstract class TableInfo implements BaseColumns
    {
        public static final String USER_NAME = "user_name";
        public static final String USER_PASS = "user_pass";
        public static final String DATABASE_NAME = "user_info";
        public static final String TABLE_NAME = "reg_info";
    }

}

数据库操作：

package cannon.gaming.mymarks;


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

/**
 * Created by Asuspc on 01/07/2015.
 */
public class DatabaseOperations extends SQLiteOpenHelper {
    public static final int database_version = 1;
    public String CREATE_QUERY = "CREATE TABLE "+ TableData.TableInfo.TABLE_NAME+"("+ TableData.TableInfo.USER_NAME+" TEXT,"+ TableData.TableInfo.USER_PASS+" TEXT);";
    public DatabaseOperations(Context context) {
        super(context, TableData.TableInfo.DATABASE_NAME, null, database_version);
        Log.d("Database Operations", "Database created");
    }

    @Override
    public void onCreate(SQLiteDatabase sdb)
    {
        sdb.execSQL(CREATE_QUERY);
        Log.d("Database Operations", "Table created");
    }
    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2)
    {

    }
    public void putInformation(DatabaseOperations dop,String name, String pass)
    {
        SQLiteDatabase SQ = dop.getWritableDatabase();
        ContentValues cv = new ContentValues();
        cv.put(TableData.TableInfo.USER_NAME, name);
        cv.put(TableData.TableInfo.USER_PASS, pass);
        long k = SQ.insert(TableData.TableInfo.TABLE_NAME, null, cv);
        Log.d("Database Operations", "One row inserted");
    }
    public Cursor getInformation(DatabaseOperations dop)
    {
        SQLiteDatabase SQ = dop.getReadableDatabase();
        String[] columns = {TableData.TableInfo.USER_NAME, TableData.TableInfo.USER_PASS};
        Cursor CR = SQ.query(TableData.TableInfo.TABLE_NAME, columns, null, null, null, null, null);
        return CR;
    }
}

现在让我解释一下。当我按下“buttonAdd”按钮时，它会让我输入主题名称，并将其保存在数据库中。

但我做不到的是，我想在 MainActivity 上显示所有数据库。它应该是这样的：

左侧的主题名称，
右侧那些主题的平均值（字符串 PASS 应该是那个平均值，这就是为什么当你第一次添加主题时它是 0）。

我想让这些主题中的每一个都可以点击，所以当你点击它时，它应该会显示该主题的所有标记，并允许你添加或删除它们。

现在，我想，显示数据应该不会那么难，但我仍然需要您的帮助。但是让每个主题都可以点击我真的不知道怎么做。每个科目都有自己的分数，我不知道，这是否意味着每个新科目或新数据库的新活动或什么？

编辑：

现在的MainActivity：

package cannon.gaming.mymarks;

import android.annotation.TargetApi;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.database.Cursor;
import android.os.Build;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.text.Html;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


public class MainActivity extends ActionBarActivity {
    String SUBJECT, PASS;
    Context CTX =  this;
    private SimpleCursorAdapter adapter;

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getSupportActionBar().hide();
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.activity_main);

        /*Button buttonAdd = (Button) findViewById(R.id.buttonAdd);
        buttonAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(v.getContext(), RegisterActivity.class);
                intent.setFlags(intent.FLAG_ACTIVITY_CLEAR_TOP);
                intent.putExtra("EXIT", true);
                startActivityForResult(intent, 0);
            }
        });*/

        Button buttonAdd = (Button) findViewById(R.id.buttonAdd);
        displayListView();
        buttonAdd.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View view) {
                showInputDialog();
            }
        });
    }

    protected void showInputDialog() {

        // get prompts.xml view
        LayoutInflater layoutInflater = LayoutInflater.from(MainActivity.this);
        View promptView = layoutInflater.inflate(R.layout.activity_dialog, null);
        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(MainActivity.this);
        alertDialogBuilder.setView(promptView);

        final EditText editText = (EditText) promptView.findViewById(R.id.edittext);
        // setup a dialog window
        alertDialogBuilder.setCancelable(false)
                .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        SUBJECT = editText.getText().toString();
                        PASS = "0";
                        DatabaseOperations DB = new DatabaseOperations(CTX);
                        DB.putInformation(DB, SUBJECT, PASS);
                        Toast.makeText(getBaseContext(), "Subject added", Toast.LENGTH_SHORT).show();
                        adapter.notifyDataSetChanged();
                        displayListView();
                    }
                })
                .setNegativeButton("Cancel",
                        new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int id) {
                                dialog.cancel();
                            }
                        });

        // create an alert dialog
        AlertDialog alert = alertDialogBuilder.create();
        alert.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.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    private void displayListView()
    {
        DatabaseOperations DOP = new DatabaseOperations(CTX);
        Cursor CR = DOP.getInformation(DOP);
        CR.moveToFirst();
        // The desired columns to be bound
        String[] columns = new String[]{
                TableData.TableInfo.USER_NAME,
                TableData.TableInfo.USER_PASS
        };
        // the XML defined views which the data will be bound to
        int[] to = new int[]{
                R.id.code,
                R.id.name,
        };
        adapter = new SimpleCursorAdapter(
                this, R.layout.activity_login,
                CR,
                columns,
                to,
                0);
        ListView listView = (ListView) findViewById(R.id.listView);
        // Assign adapter to ListView
        listView.setAdapter(adapter);
    }
}

【问题讨论】：

标签： java android sqlite android-studio

【解决方案1】：

要显示数据，您应该使用 ListView 和 CursorAdapter。这是给你的示例代码：http://www.mysamplecode.com/2012/07/android-listview-cursoradapter-sqlite.html

在该示例代码中，您可以看到：

listView.setOnItemClickListener(new OnItemClickListener() {
   @Override
   public void onItemClick(AdapterView<?> listView, View view, 
     int position, long id) {
   // Get the cursor, positioned to the corresponding row in the result set
   Cursor cursor = (Cursor) listView.getItemAtPosition(position);

   // Get the state's capital from this row in the database.
   String countryCode = 
    cursor.getString(cursor.getColumnIndexOrThrow("code"));
   Toast.makeText(getApplicationContext(),
     countryCode, Toast.LENGTH_SHORT).show();

   }
});

OnItemClickListener 将帮助您处理单击列表视图中的项目。

希望这会对你有所帮助。

【讨论】：

我一直在尝试用你给我的那个链接来修复它，现在我有这个错误：java.lang.RuntimeException: Unable to start activity ComponentInfo{cannon.gaming.mymarks/cannon.gaming. mymarks.MainActivity}：java.lang.IllegalArgumentException：列“_id”不存在
我编辑了上面的问题并添加了我的 MainActivity 代码现在的样子
刚刚修好了，谢谢 :D
我现在有另一个问题，如何将新列添加到特定行？
我不明白你的问题。是否要向数据库表中添加新列？