java - 在android编程中使用类的方法

Question

大家好，我是android初学者，请帮忙。我有 DBAdapter 类，它有不同的方法来操作我的数据库。我想调用该方法，即单击按钮时插入。但是它只能在监听器 (View.OnClickListener) 之外工作。

    package com.dbclass;

    import android.app.Activity;
    import android.database.Cursor;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.Toast;

    public class DBActivity extends Activity {
        /** Called when the activity is first created. */
       @Override
       public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button btn1 = (Button)findViewById(R.id.Button01);
        btn1.setOnClickListener(btn1Listener);


        DBAdapter db = new DBAdapter(this);        
        db.open();  

        long id;
         // this needs to go to setOnclick method
        id = db.insertTitle(
                "0470285818",
                "Alanel",
                "Wrox");        

        Cursor c = db.getAllTitles();
        if (c.moveToFirst())
        {
            do {          
                DisplayTitle(c);
            } while (c.moveToNext());
        }
        db.close();
    }

    public void DisplayTitle(Cursor c)
    {
        Toast.makeText(this, 
                "id: " + c.getString(0) + "\n" +
                "ISBN: " + c.getString(1) + "\n" +
                "TITLE: " + c.getString(2) + "\n" +
                "PUBLISHER:  " + c.getString(3),
                Toast.LENGTH_LONG).show();        
    }
    private View.OnClickListener btn1Listener = new View.OnClickListener() {
        @Override
        public void onClick(View v) {
                 // db.insertTitle("0470285818", "Alanel", "Wrox");  

        }
    };
}

Answer 1

将您的 db 变量设置为 DBActivity 的字段。不过，您可能不想在 UI 线程上执行数据库操作。