我在 Android studio 上的应用程序在创建第一个数据后崩溃了

问题描述 投票：0回答：1

如果我的数据库中没有任何类型（对象），那么应用程序会正常运行，但是在我将第一个东西添加到数据库后，它会立即崩溃，如果我再次运行它，它仍然会崩溃。

我不知道该怎么办。是因为它无法读取数据还是因为我一开始就没有创建任何东西？ 35：lstType = TypeDataQuery.getAll(this);如果我删除这条线，事情就会正常运行

package com.example.myspinner;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

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

import java.util.ArrayList;

public class TypeActivity extends AppCompatActivity implements TypeAdapter.TypeCallBack {
    TextView tvHeaderC;
    RecyclerView rcListCode;
    ArrayList<Type> lstType;
    TypeAdapter typeAdapter;
    FloatingActionButton fbTypeAdd;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_type);
        tvHeaderC = findViewById(R.id.tvTypeHeader);
        rcListCode = findViewById(R.id.rvTypeList);
        fbTypeAdd = findViewById(R.id.fbTypeAdd);
        fbTypeAdd.setOnClickListener(view -> addTypeDialog());

        lstType = new ArrayList<>();
        lstType = TypeDataQuery.getAll(this);
        typeAdapter = new TypeAdapter(lstType);
        typeAdapter.setTypeCallBack((TypeAdapter.TypeCallBack) this);

        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        rcListCode.setAdapter(typeAdapter);
        rcListCode.setLayoutManager(linearLayoutManager);
    }
    void addTypeDialog()
    {
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(TypeActivity.this);
        alertDialog.setTitle("Thêm mới");
        LayoutInflater inflater = this.getLayoutInflater();
        View dialogView = inflater.inflate(R.layout.dialog_add_type, null);
        alertDialog.setView(dialogView);
        EditText edTypeName = dialogView.findViewById(R.id.edTypeName);
        alertDialog.setPositiveButton("Đồng ý", ((dialog, which) ->
        {
            String name = edTypeName.getText().toString();
            if (name.isEmpty())
                Toast.makeText(TypeActivity.this, "Nhập dữ liệu không hợp lệ", Toast.LENGTH_LONG).show();
            else {
                Type type = new Type(0, name);
                long id = TypeDataQuery.insert(TypeActivity.this, type);
                if (id > 0) {
                    Toast.makeText(TypeActivity.this, "Thêm loại thành công.", Toast.LENGTH_LONG).show();
                    resetData();
                    dialog.dismiss();
                }
            }
        }
        ));
        alertDialog.setNegativeButton("Hủy", ((dialog, which) ->
        {
            dialog.dismiss();
        }
        ));
        alertDialog.create();
        alertDialog.show();
    }
    void resetData() {
        lstType.clear();
        lstType.addAll(TypeDataQuery.getAll(TypeActivity.this));
        typeAdapter.notifyDataSetChanged();
    }
    void updateUserDialog(Type type) {
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(TypeActivity.this);
        alertDialog.setTitle("Cập nhật");
        LayoutInflater inflater = this.getLayoutInflater();
        View dialogView = inflater.inflate(R.layout.dialog_add_type, null);
        alertDialog.setView(dialogView);
        EditText edName = (EditText) dialogView.findViewById(R.id.edTypeName);

        edName.setText(type.getName());
        alertDialog.setPositiveButton("Đồng ý", (dialog, which) -> {
            type.setName(edName.getText().toString());
            if (type.name.isEmpty())
                Toast.makeText(TypeActivity.this, "Nhập dữ liệu không hợp lệ", Toast.LENGTH_LONG).show();
            else {
                int id = TypeDataQuery.update(TypeActivity.this, type);
                if (id > 0) {
                    Toast.makeText(TypeActivity.this, "Cập nhật người dùng thành công.", Toast.LENGTH_LONG).show();
                    resetData();
                    dialog.dismiss();
                }
            }
        });
        alertDialog.setNegativeButton("Hủy", (dialog, which) -> {
            dialog.dismiss();
        });
        alertDialog.create();
        alertDialog.show();
    }

    @Override
    public void onItemDeleteClicked(Type type, int position) {
        boolean rs = TypeDataQuery.delete(TypeActivity.this, type.id);
        if (rs) {
            Toast.makeText(this, "Xoá thành công", Toast.LENGTH_LONG).show();
            resetData();
        } else {
            Toast.makeText(this, "Xoá thất bại", Toast.LENGTH_LONG).show();
        }
    }

    @Override
    public void onItemEditClicked(Type type, int position) {
        updateUserDialog(type);
    }
}

package com.example.myspinner;

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

public class UserDBHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = utils.DATABASE_NAME;
    private static final int DATABASE_VERSION = 4;
    public UserDBHelper(Context context)
    {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_USER_TABLE = "CREATE TABLE " + utils.TABLE_USER + " ("
                + utils.COLUMN_USER_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
                + utils.COLUMN_USER_NAME + " TEXT, "
                + utils.COLUMN_USER_AVATAR + " TEXT" + ");";

        String CREATE_TYPE_TABLE = "CREATE TABLE " + utils.TABLE_TYPE + " ("
                + utils.COLUMN_TYPE_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
                + utils.COLUMN_TYPE_NAME + " TEXT" + ");" ;
        db.execSQL(CREATE_USER_TABLE);
        db.execSQL(CREATE_TYPE_TABLE);
    }

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


package com.example.myspinner;

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

import java.util.ArrayList;

public class TypeDataQuery {
    public static long insert(Context context, Type type)
    {
        UserDBHelper userDBHelper = new UserDBHelper(context);
        SQLiteDatabase sqLiteDatabase = userDBHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(utils.COLUMN_TYPE_NAME, type.name);
        long rs = sqLiteDatabase.insert(utils.TABLE_TYPE, null, values);
        return (rs);
    }
    public static ArrayList<Type> getAll(Context context)
    {
        ArrayList<Type> lstUser = new ArrayList<>();
        UserDBHelper userDBHelper = new UserDBHelper(context);
        SQLiteDatabase db = userDBHelper.getReadableDatabase();
        Cursor cs = db.rawQuery("Select * from " + utils.TABLE_TYPE, null);
        cs.moveToFirst();
        while (!cs.isAfterLast())
        {
            int id = cs.getInt(0);
            String name = cs.getString(1);
            Type type = new Type(id, name);
            lstUser.add(type);
            cs.moveToNext();
        }
        cs.close();
        db.close();
        return lstUser;
    }
    public static boolean delete(Context context, int id)
    {
        UserDBHelper userDBHelper = new UserDBHelper(context);
        SQLiteDatabase sqLiteDatabase = userDBHelper.getWritableDatabase();
        int rs = sqLiteDatabase.delete(utils.TABLE_TYPE, utils.COLUMN_TYPE_ID+"=?", new String[]{String.valueOf(id)});
        return (rs > 0);
    }
    public static int update(Context context, Type type)
    {
        UserDBHelper userDBHelper = new UserDBHelper(context);
        SQLiteDatabase sqLiteDatabase = userDBHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(utils.COLUMN_TYPE_NAME, type.name);
        int rs = sqLiteDatabase.update(utils.TABLE_TYPE, values, utils.COLUMN_TYPE_ID+"=?", new String[] {String.valueOf(type.id)} );
        return (rs);
    }
}


package com.example.myspinner;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
public class TypeAdapter extends RecyclerView.Adapter<TypeAdapter.TypeViewHolder> {
    ArrayList<Type> lstType;
    Context context;
    TypeCallBack typeCallBack;
    public TypeAdapter(ArrayList<Type> lstType) {
        this.lstType = lstType;
    }
    public void setTypeCallBack(TypeCallBack typeCallBack)
    {
        this.typeCallBack = typeCallBack;
    }

    @NonNull
    @Override
    public TypeViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        context = parent.getContext();
        LayoutInflater inflater = LayoutInflater.from(context);
        View typeView = inflater.inflate(R.layout.layoutitem, parent, false);
        return new TypeViewHolder(typeView);
    }

    @Override
    public void onBindViewHolder(@NonNull TypeViewHolder holder, int position) {
        Type item = lstType.get(position);
        if(item != null)
        {
            holder.tvName.setText(item.getName());
            holder.ivEdit.setOnClickListener(view -> typeCallBack.onItemEditClicked(item, position));
            holder.ivDelete.setOnClickListener(view -> typeCallBack.onItemDeleteClicked(item, position));
        }

    }

    @Override
    public int getItemCount() {
        return lstType.size();
    }
    static class TypeViewHolder extends RecyclerView.ViewHolder
    {
        TextView tvName;
        ImageView ivEdit;
        ImageView ivDelete;
        public TypeViewHolder(@NonNull View itemView) {
            super(itemView);
            tvName = itemView.findViewById(R.id.tvTypeName);
            ivEdit = itemView.findViewById(R.id.ivTypeEdit);
            ivDelete = itemView.findViewById(R.id.ivTypeDelete);
        }
    }
    public interface TypeCallBack
    {
        void onItemDeleteClicked(Type type, int position);
        void onItemEditClicked(Type type, int position);
    }
}


package com.example.myspinner;

public class Type {
    int id;
    String name;

    public Type(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}
crash android-sqlite
1个回答
0
投票

如果没有要提取的数据，则

moveToFirst
的结果将为假（无法完成移至第一行）。如果在不检查结果的情况下尝试提取数据，则会发生异常（崩溃）。

您必须检查

moveToFirst
是否成功。

使用起来更简单、更简洁：-

    Cursor cs = db.rawQuery("Select * from " + utils.TABLE_TYPE, null);
    //cs.moveToFirst();
    while (cs.moveToNext)
    {
        int id = cs.getInt(0);
        String name = cs.getString(1);
        Type type = new Type(id, name);
        lstUser.add(type);
    }
  • 请注意，
    cs.moveToFirst
    行已被注释掉（否则将跳过 1 行）。显然，该行可以删除（保留以进行说明）。
  • moveToNext
    将有效地从第一行之前的位置移动到第一行，如果无法移动则返回 false。
最新问题
© www.soinside.com 2019 - 2024. All rights reserved.