Question

我正在尝试在我的android项目上创建一个简单的SQLite来完成一些工作。 MyDBHandler中MyDBHandler（）的(this,null, null,null 1)行无法应用于此。我有一种感觉，因为这是一个片段，而不是通常的活动。有什么想法吗？

package com.test.test.sql;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;


/**
 * A simple {@link Fragment} subclass.
 */
public class MemoFragment extends Fragment {

    EditText Input;
    TextView LyricText;
    MyDBHandler dbHandler;
    Button addButtonClicked;
    Button deleteButtonClicked;

    public MemoFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_memo, container, false);

        Input = (EditText) getView().findViewById(R.id.Input);
        LyricText = (TextView) getView().findViewById (R.id.LyricText);
        dbHandler = new MyDBHandler(this, null, null, 1);
        printDatabase ();
    }
    //add lyric to database
    public void addButtonClicked(View view){
        Lyrics lyrics = new Lyrics(Input.getText().toString());
        dbHandler.addLyric(lyrics);
        printDatabase();
    }

    //delete items
    public void deleteButtonClicked(View view){
        String inputText = Input.getText().toString());
        dbHandler.deleteLyrics(inputText);
        printDatabase();
    }

    public void printDatabase(){
        String dbString = dbHandler.databasetoString();
        LyricText.setText(dbString);
        Input.setText("");
    }

}

Answer 1

你的onCreateView错了。当您将返回放置在该位置时，以下行不会被执行。因此，首先将膨胀的布局放在View变量上。然后使用它来实例化edittext和textview。请参阅下面的代码

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View v = inflater.inflate(R.layout.fragment_memo, container, false);

    Input = (EditText) v.findViewById(R.id.Input);
    LyricText = (TextView) v.findViewById (R.id.LyricText);
    dbHandler = new MyDBHandler(this, null, null, 1);
    printDatabase ();
    return v;
}

Answer 2

这个怎么样：

dbHandler = new MyDBHandler(getActivity(),null,null,1);

关于片段的SQLite

2 个答案: