Android Studio应用程序在数据库插入时崩溃

时间:2017-01-20 17:43:05

标签: java android sqlite sqliteopenhelper

当我调用'test'函数时,我的应用程序崩溃了。任何想法为什么会发生这种情况?

数据库类

package com.example.paulcosma.app2;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;


public class DB extends SQLiteOpenHelper{
    public static final String
            dbName = "foods.db",
            tableName = "foods",
            colId = "id",colName = "name",colCarbs = "carbs";

    public DB(Context context) {
        super(context, dbName, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + dbName + "( " + colId + " INTEGER PRIMARY KEY AUTOINCREMENT," + colName + " TEXT," + colCarbs + " REAL)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("drop table if exists " + dbName);
        onCreate(db);
    }

    public boolean addFood(String Name, float Carbs){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(colName,Name);
        contentValues.put(colCarbs,Carbs);
        long result = db.insert(tableName,null,contentValues);

        return result != -1; // -1 == not inserted
    }
}

MainActivity

package com.example.paulcosma.app2;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    DB db;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        db = new DB(this);
    }
    public void test(View v){
        boolean insertedSuccessfully = db.addFood("Milk",4); // crashes when called
        if(insertedSuccessfully)
            Toast.makeText(this,"inserted",Toast.LENGTH_LONG).show();
        else Toast.makeText(this,"not inserted",Toast.LENGTH_LONG).show();
    }

}

logcat

  

01-20 19:59:47.888 9565-9565 / com.example.paulcosma.app2 E / InstantRun:   无法在APK中找到切片;中止。 01-20 19:59:47.988   9565-9565 / com.example.paulcosma.app2 E / dalvikvm:找不到课程   'android.graphics.drawable.RippleDrawable',从方法引用   android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering   01-20 19:59:48.005 9565-9565 / com.example.paulcosma.app2 E / TextView:   zhangcl:从应用程序获取字体资源失败。 01-20   19:59:48.013 9565-9565 / com.example.paulcosma.app2 E / TextView:zhangcl:   从应用程序获取字体资源失败 - 2. 01-20 19:59:48.045   9565-9565 / com.example.paulcosma.app2 E / TextView:zhangcl:get font   应用程序资源失败。 01-20 20:00:02.211   9565-9565 / com.example.paulcosma.app2 E / SQLiteLog:(10)无法做到   file read,got:0,amt:100,last Errno:2 01-20 20:00:02.244   9565-9565 / com.example.paulcosma.app2 E / SQLiteLog:(1)未知数据库   食品01-20 20:00:02.263 9565-9565 / com.example.paulcosma.app2   E / AndroidRuntime:致命例外:主要                                                                             过程:com.example.paulcosma.app2,PID:9565
                                                                            java.lang.IllegalStateException:无法执行方法   机器人:的onClick

1 个答案:

答案 0 :(得分:0)

你在onCreate()中输了一个拼写错误。您正在使用dbName而不是tableName来创建表格,因此,当您运行查询 查找正确的名称时,您就可以&# 39;重新查找一张不存在的表格。所以:

db.execSQL("create table " + dbName + "( " + colId + " INTEGER PRIMARY KEY AUTOINCREMENT," + colName + " TEXT," + colCarbs + " REAL)");

需要成为:

db.execSQL("create table " + tableName + "( " + colId + " INTEGER PRIMARY KEY AUTOINCREMENT," + colName + " TEXT," + colCarbs + " REAL)");