Question

我的MainActivity中出现错误。产品中的 产品（）无法应用于（java.lang.String） 这是代码

        import android.os.Bundle;
        import android.support.v7.app.AppCompatActivity;
        import android.util.Log;
        import android.view.View;
        import android.widget.EditText;
        import android.widget.TextView;
        import apps.fsc.foodtrackertuesday.R;

// This program exists solely to generate a database and play with it.

public class MainActivity extends AppCompatActivity {
    EditText userEntryText;
    TextView resultsText;
    myDBManager dbManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Grab references to UI elements
        userEntryText   = findViewById(R.id.userEntryText);
        resultsText     = findViewById(R.id.resultsText);

        // dbManager reference
        dbManager = new myDBManager(this, null, null, 1);

        // Let's see what's in the database.
        printDatabase();
    }

    public void printDatabase()
    {
        // Query the database using the dbManager's dbToString() method.
        String dbString = dbManager.dbToString();
        // Drop the results onto the UI
        resultsText.setText(dbString);
        // Set the UI up for fresh input
        userEntryText.setText("");
    }

    public void addFRUITButtonClick(View view)
    {
        // Create a new product based on what's in the UI
        Products products = new Products(userEntryText.getText().toString());
        // Send that product object to the dbManager so the item can be added.
        dbManager.addFRUITItem(products);
        // See what's in the database
        printDatabase();

    }

    public void delFRUITButtonClick(View view)
    {
        // Grab the UI contents and dump it into a string
        String inputText = userEntryText.getText().toString();
        // Send that string to the dbManager's delItem() method.
        dbManager.delFRUITItem(inputText);
        // See what's in the database
        printDatabase();
    }
}

这是MyDBManager

package apps.fsc.foodtrackertuesday;



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



public class myDBManager extends SQLiteOpenHelper{
    // Define some global database stuff

    private static final int        DATABASE_VERSION    = 1;
    private static final String     DATABASE_NAME       = "database";

    // Define a table and some columns
    private static final String     TABLE_NAME                  = "products";
    private static final String     COLUMN_ID                   = "_id";
    private static final String     COLUMN_PRODUCT_FRUIT        = "productfruit";
    private static final String     COLUMN_PRODUCT_DAIRY        = "productdairy";
    private static final String     COLUMN_PRODUCT_GRAINS       = "productgrains";
    private static final String     COLUMN_PRODUCT_VEGETABLES   = "productvegetables";
    private static final String     COLUMN_PRODUCT_PROTEIN      = "productprotein";


    public myDBManager(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        //super(context, name, factory, version); // original super.
        super(context, DATABASE_NAME, factory , DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // put together a sql string to create the table
        String query =  "CREATE TABLE "         + TABLE_NAME + "(" +
                COLUMN_ID                       + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                COLUMN_PRODUCT_FRUIT            + " VARCHAR(255) " +
                COLUMN_PRODUCT_DAIRY            + " VARCHAR(255) " +
                COLUMN_PRODUCT_GRAINS           + " VARCHAR(255) " +
                COLUMN_PRODUCT_VEGETABLES       + " VARCHAR(255) " +
                COLUMN_PRODUCT_PROTEIN          + " VARCHAR(255) " +
                ");";
        // execute the sql command
        db.execSQL(query);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // delete the existing database
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        // call onCreate
        onCreate(db);
    }

    // Add item to database
    public void addFRUITItem(Products _productFRUIT){
        // get reference to the database
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        // Associate column name with value
        values.put(COLUMN_PRODUCT_FRUIT, _productFRUIT.get_productFRUIT());
        // insert value into table at the appropriate location
        db.insert(TABLE_NAME, null, values);
        // done writing
        db.close();
    }
    public void addDAIRYItem(Products product_dairy){
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_PRODUCT_DAIRY, product_dairy.get_productFRUIT());
        db.insert(TABLE_NAME, null, values);
        db.close();
    }
    public void addVEGETABLESItem(Products product_vegetables){
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_PRODUCT_VEGETABLES, product_vegetables.get_productFRUIT());
        db.insert(TABLE_NAME, null, values);
        db.close();
    }
    public void addGRAINSItem(Products product_grain){
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_PRODUCT_GRAINS, product_grain.get_productFRUIT());
        db.insert(TABLE_NAME, null, values);
        db.close();
    }
    public void addPROTEINItem(Products product_protein){
        SQLiteDatabase db = getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_PRODUCT_PROTEIN, product_protein.get_productFRUIT());
        db.insert(TABLE_NAME, null, values);
        db.close();
    }

    // Delete an item from the database
    public void delDAIRYItem(String product_dairy){
        // Get database reference
        SQLiteDatabase db = getWritableDatabase();

        // build the sql query
        String query =  "DELETE FROM "  + TABLE_NAME +
                " WHERE "       + COLUMN_PRODUCT_DAIRY +
                "=\""           + product_dairy + "\";";
        //execute the query
        db.execSQL(query);
    }
    public void delFRUITItem(String product_fruit){
        // Get database reference
        SQLiteDatabase db = getWritableDatabase();

        // build the sql query
        String query =  "DELETE FROM "  + TABLE_NAME +
                " WHERE "       + COLUMN_PRODUCT_FRUIT +
                "=\""           + product_fruit + "\";";
        //execute the query
        db.execSQL(query);
    }
    public void delGRAINStem(String product_grains){
        // Get database reference
        SQLiteDatabase db = getWritableDatabase();

        // build the sql query
        String query =  "DELETE FROM "  + TABLE_NAME +
                " WHERE "       + COLUMN_PRODUCT_GRAINS +
                "=\""           + product_grains + "\";";
        //execute the query
        db.execSQL(query);
    }
    public void delVEGETABLESItem(String product_vegetables){
        // Get database reference
        SQLiteDatabase db = getWritableDatabase();

        // build the sql query
        String query =  "DELETE FROM "  + TABLE_NAME +
                " WHERE "       + COLUMN_PRODUCT_VEGETABLES +
                "=\""           + product_vegetables + "\";";
        //execute the query
        db.execSQL(query);
    }
    public void delPROTEINItem(String product_protein){
        // Get database reference
        SQLiteDatabase db = getWritableDatabase();

        // build the sql query
        String query =  "DELETE FROM "  + TABLE_NAME +
                " WHERE "       + COLUMN_PRODUCT_PROTEIN +
                "=\""           + product_protein + "\";";
        //execute the query
        db.execSQL(query);
    }

    public String dbToString()
    {
        // Get a reference to the database
        SQLiteDatabase db = getWritableDatabase();
        String dbString = "";

        // Build a sql query
        String query = "SELECT * FROM " + TABLE_NAME + " WHERE 1";

        // Point the cursor at the result of the executed query
        Cursor c = db.rawQuery(query, null);

        // Start at the beginning
        c.moveToFirst();

        // Iterate through the rows until the end is reached
        while(!c.isAfterLast()){
            if(c.getString(c.getColumnIndex(COLUMN_ID))!=null){
                // dbString += c.getString(c.getColumnIndex(COLUMN_ID));
                dbString += " ";
                dbString += c.getString(c.getColumnIndex(COLUMN_PRODUCT_FRUIT));
                dbString += "\n";
            }
            // point to the next row
            c.moveToNext();
        }
        // close the database
        db.close();
        // send back the data
        return dbString;
    }
}

这是我的产品表

package apps.fsc.foodtrackertuesday;

公共类产品 {

private int _id;
private String _productFRUIT;
private String _productDAIRY;
private String _productGRAINS;
private String _productPROTEIN;
private String _productVEGETABLES;




public void _productFRUIT(String _productFRUIT)
{
    this._productFRUIT = _productFRUIT;
}

public void _productDAIRY(String _productDAIRY)
{
    this._productDAIRY = _productDAIRY;
}

public void _productGRAINS(String _productGRAINS)
{
    this._productGRAINS = _productGRAINS;
}

public void _productPROTEIN(String _productPROTEIN)
{
    this._productPROTEIN = _productPROTEIN;
}

public void _productVEGETABLES(String _productVEGETABLES)
{
    this._productVEGETABLES = _productVEGETABLES;
}
//Getters

public int get_id()
{
    return _id;
}
public String get_productFRUIT()
{
    return _productFRUIT;
}
public String get_productGRAINS()
{
    return _productGRAINS;
}
public String get_productVEGETABLES()
{
    return _productVEGETABLES;
}
public String get_productPROTEIN()
{
    return _productPROTEIN;
}
public String get_productDAIRY()
{
    return _productDAIRY;
}


//Setters
public void set_id(int _id) {
    this._id = _id;
}
public void set_productFRUIT(String _productFRUIT)
{
    this._productFRUIT = _productFRUIT;
}
public void set_productDAIRY(String _productDAIRY)
{
    this._productDAIRY = _productDAIRY;
}
public void set_productGRAINS(String _productGRAINS)
{
    this._productGRAINS = _productGRAINS;
}
public void set_productVEGETABLES(String _productVEGETABLES)
{
    this._productVEGETABLES = _productVEGETABLES;
}
public void set_productPROTEIN(String _productPROTEIN)
{
    this._productPROTEIN = _productPROTEIN;
}
}

为什么会发生这种情况？如何解决这个问题？一点背景：
它是一个应用程序，用于存储在杂货店中可以获得的东西它被细分为食物组。

Answer 1

在产品表

上

public Products(String productName) {
    this._productFRUIT = productName;
}

产品中的Products（）无法应用于（java.lang.String）错误

1 个答案: