Question

我是Android的初学者。请帮我解决这个简单的问题：从SQLite中检索一个数据。

案例1：

dbhelper.java
// Getting single part
    public lispar Look(int id) {
        SQLiteDatabase db = this.getReadableDatabase();

        Cursor kr = db.query(TABLE_PART, new String[]{ID,
                        KODE, NAMA}, ID + "=?",
                new String[]{String.valueOf(id)}, null, null, null, null);
        if (kr != null)
            kr.moveToFirst();

        lispar contact = new lispar(Integer.parseInt(kr.getString(0)),
                kr.getString(1), kr.getString(2));
        // return contact
        kr.close();
        db.close();
        return contact;
    }

main.java
kodcari = (Button) findViewById(R.id.carikod);
        kodcari.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v){

                ckodin = kodin.getText().toString(); //wrong string?
                parin.getText().toString();
                //what should i do?
            }
        });

        partnam = (EditText) findViewById(R.id.namepart);
        dbHandle = new DbHandle(this);


    }

案例2：

main.java ()

kodin = (EditText) findViewById(R.id.inkod);
        kodcari = (Button) findViewById(R.id.carikod);
        kodcari.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                SQLiteDatabase db = mDbHelper.getReadableDatabase();
                String[] projection = {
                        FeedEntry._ID,
                        FeedEntry.KODE,
                        FeedEntry.NAMPART,
                        FeedEntry.BELANG
                };

                // Filter results WHERE "kode" = 'kode part'
                String selection = FeedEntry.KODE + " = ?";
                String[] selectionArgs = parin.getText().toString(), belangin.getText().toString();//{ "KODE_PART" }; //

                // How you want the results sorted in the resulting Cursor
                String sortOrder = FeedEntry.KODE + " DESC";

                Cursor kr = db.query(
                        FeedEntry.KODE,         // The table to query
                        projection,             // The columns to return
                        selection,              // The columns for the WHERE clause
                        selectionArgs,          // The values for the WHERE clause
                        null,                   // don't group the rows
                        null,                   // don't filter by row groups
                        sortOrder               // The sort order
                );
                if (kr != null)
                kr.moveToFirst();
                //String parin = kr.getString(
                //kr.getColumnIndexOrThrow(FeedEntry._ID)
                //);

            }
        });

main.xml中

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Looking by Code"
        android:textSize="10pt"
        android:id="@+id/txkod"
        android:layout_marginTop="63dp"
        android:layout_centerHorizontal="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="insert code"
        android:textAlignment="center"
        android:layout_marginTop="25dp"
        android:id="@+id/inkod"
        android:layout_below="@+id/txkod"
        android:layout_alignLeft="@+id/txkod"
        android:layout_alignStart="@+id/txkod"
        android:layout_alignRight="@+id/txkod"
        android:layout_alignEnd="@+id/txkod" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Look"
        android:id="@+id/carikod"
        android:layout_below="@+id/inkod"
        android:layout_centerHorizontal="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/codepar"
        android:hint="code part"
        android:layout_below="@+id/namkod"/>

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/nampar"
        android:hint="name part"
        android:layout_below="@+id/nampar"/>

</LinearLayout>

插入数据是成功的，但是读取数据不是。（基准意味着数据*）

enter image description here

Answer 1

我不确定以下内容会让你感动。但似乎您没有获得 kodin 和 parin 视图的ID。所以也许尝试以下方法： -

 kodin = (EditText) findViewById(R.id.inkod);
 parin = (EditText) findViewById(R.id.nampar);

更详细的代码（未经测试和即时编写，因此可能有错误）

如果您正在使用Android Studio或IDE进行调试，那么使用它可能非常有用。

    kodcari = (Button) findViewById(R.id.carikod);
    // Adding the following lines may get the correct string
    kodin = (EditText) findViewById(R.id.inkod); //????
    parin = (EditText) findViewById(R.id.nampar); //????
    kodcari.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v){

            ckodin = kodin.getText().toString(); //wrong string?
            parin.getText().toString();
            //what should i do? Perhaps the following :-
            lipsar myContact = Look(ckodin !!!!CONVERTED TO INT FROM STRING);
            // whatever else you need to do with the mycontact .....

        }
    });

    partnam = (EditText) findViewById(R.id.namepart);
    dbHandle = new DbHandle(this);


}

SQLite获取单个数据（*单个数据）（更新帖子）

1 个答案: