家庭记账小账本Android studio

package com.example.bank;

import android.database.Cursor;
import android.os.Bundle;

import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;

import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private List<CostBean> mCostBeanList;
    private DatabaseHelper mDatabaseHelper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        mDatabaseHelper=new DatabaseHelper(this);
      mCostBeanList=new ArrayList<>();
      ListView costList=(ListView) findViewById(R.id.lv_main);
      initCostData();
      costList.setAdapter(new CostListAdapter(this,mCostBeanList));

      FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }

    private void initCostData() {
        mDatabaseHelper.deleteAllData();
        for (int i=0;i<6;i++) {
            CostBean costBean=new CostBean();
            costBean.costTitle=i+"mook";
            costBean.costDate="11-11";
            costBean.costMoney="20";
           mDatabaseHelper.insertCost(costBean);
        }
       Cursor cursor= mDatabaseHelper.getAllCostData();
        if(cursor !=null)
        {
            while(cursor.moveToNext()){
                CostBean costBean=new CostBean();
                costBean.costTitle=cursor.getString(cursor.getColumnIndex("cost_title"));
                costBean.costDate=cursor.getString(cursor.getColumnIndex("cost_date"));
                costBean.costMoney=cursor.getString(cursor.getColumnIndex("cost_money"));
                mCostBeanList.add(costBean);
            }
            cursor.close();
        }
    }

    @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);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="80dp">
    <TextView
        android:id="@+id/tv_title"
        android:layout_width="200dp"
        android:layout_height="80dp"
        android:layout_alignParentLeft="true"
        android:gravity="center"
        android:singleLine="true"
        android:text="costTitle"
        android:ellipsize="marquee"
        android:layout_marginLeft="10dp"
        android:textSize="35sp" />
    <TextView
        android:id="@+id/tv_date"
        android:layout_width="wrap_content"
        android:layout_height="80dp"
        android:gravity="center"
        android:textSize="20sp"
        android:layout_marginLeft="15dp"
        android:layout_toRightOf="@id/tv_title"
        android:text="costDate"
        />
    <TextView
        android:id="@+id/tv_cost"
        android:layout_width="wrap_content"
        android:layout_height="80dp"
        android:gravity="center"
        android:layout_alignParentRight="true"
        android:textSize="30sp"
        android:layout_marginRight="20dp"
        android:text="30"
        />

</RelativeLayout>

package com.example.bank;

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

import androidx.annotation.Nullable;

public class DatabaseHelper extends SQLiteOpenHelper {

    public DatabaseHelper(@Nullable Context context) {
        super(context, "imooc_daily", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    db.execSQL("creat table if not exists imooc_cost("+
            "id integer primary key,"+
            "cost_title varchar,"+
            "cost_date varchar,"+
            "cost_money varchar)");
    }
    public void insertCost(CostBean costBean)
    {
        SQLiteDatabase database=getWritableDatabase();
        ContentValues cv=new ContentValues();
        cv.put("cost_title",costBean.costTitle);
        cv.put("cost_date ",costBean.costDate);
        cv.put("cost_money",costBean.costMoney);
        database.insert("imooc_cost",null,cv);
    }
    public Cursor getAllCostData(){
        SQLiteDatabase database=getWritableDatabase();
        return database.query("imooc_cost",null,null,null,null,null,"cost_date "+"ASC");

    }
    public void deleteAllData(){
        SQLiteDatabase database=getWritableDatabase();
        database.delete("imooc_cost",null,null);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".MainActivity"
    tools:showIn="@layout/activity_main">

    <ListView
        android:id="@+id/lv_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />

</RelativeLayout>