如何在数据库中使用微调器列表

Question

现在，我创建了一个在程序中显示的微调器列表，并且有多种选择。如果我想使用微调器列表来选择一个项目，那么所选项目将使用 SQLite 代码添加到数据库中。另外，如何在“金额”之后的下一行显示所选项目？

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

    dbhelper = new DBhelper(this);
    db = dbhelper.getWritableDatabase();
    tEvent = (EditText) findViewById(R.id.event);
    tLocation = (EditText) findViewById(R.id.venue);
    tAmount = (EditText) findViewById(R.id.amount);

    spin = (Spinner) findViewById(R.id.spinner);
    list.add("---CATEGORIES---");
    list.add("Eating");
    list.add("Entertainment");
    list.add("Shopping");
    list.add("Transportation");
    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, list);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spin.setAdapter(adapter);
}

protected void onStop() {
    super.onStop();
    db.close();
}

public void Badd_Click(View view){
        db.execSQL("INSERT INTO Demo (event, venue, amount, textView) VALUES ('" + tEvent.getText().toString() + "'," + "'" + tLocation.getText().toString() + "'," + "'" + tAmount.getText().toString() +"' )");
        Toast.makeText(this, "Create record successfully...", Toast.LENGTH_SHORT).show();
    }

public void Btnshow_Click(View view){
    String str = "";
    Cursor c = db.rawQuery("SELECT * FROM "+DATABASE_TABLE,null);
    c.moveToFirst();
    for(int i = 0; i<c.getCount();i++){
        str+="ID: "+c.getString(0)+"\n";
        str+="Name : "+c.getString(1)+"\n";
        str+="Location : "+c.getString(2)+"\n";
        str+="Amount : "+c.getString(3)+"\n\n";
        c.moveToNext();
    }

    Builder MyAlertDialog = new AlertDialog.Builder(this);
    MyAlertDialog.setTitle("Records");
    MyAlertDialog.setMessage(str);
    DialogInterface.OnClickListener OkClick = new DialogInterface.OnClickListener()
    {
        public void onClick(DialogInterface dialog, int which) {
        }
    };
    MyAlertDialog.setNeutralButton("OK",OkClick );
    MyAlertDialog.show();
}

}

Answer 1

使用 OnItemSelectedListener

private String category;
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    dbhelper = new DBhelper(this);
    db = dbhelper.getWritableDatabase();
    tEvent = (EditText) findViewById(R.id.event);
    tLocation = (EditText) findViewById(R.id.venue);
    tAmount = (EditText) findViewById(R.id.amount);

    spin = (Spinner) findViewById(R.id.spinner);

    list.add("---CATEGORIES---");
    list.add("Eating");
    list.add("Entertainment");
    list.add("Shopping");
    list.add("Transportation");

    adapter = new ArrayAdapter < String > (this, android.R.layout.simple_spinner_item, list);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

    spin.setAdapter(adapter);
    spin.setOnItemSelectedListener(new OnItemSelectedListener() {
        public void onItemSelected(AdapterView parent, View view, int pos, long id) {
            category = parent.getItemAtPosition(pos).toString();
        }
        public void onNothingSelected(AdapterView parent) {
            category = null;
        }
    });
}

protected void onStop() {
    super.onStop();
    db.close();
}

public void Badd_Click(View view) {
    db.execSQL("INSERT INTO Demo (event, venue, amount, textView) VALUES ('" + tEvent.getText().toString() + "'," + "'" + tLocation.getText().toString() + "'," + "'" + tAmount.getText().toString() + "' )");
    db.execSQL("INSERT INTO Demo (category) VALUES ('" + category + "');"); // ONLY EXAMPLE
    Toast.makeText(this, "Create record successfully...", Toast.LENGTH_SHORT).show();
}

public void Btnshow_Click(View view) {
    String str = "";
    Cursor c = db.rawQuery("SELECT * FROM " + DATABASE_TABLE, null);
    c.moveToFirst();
    for (int i = 0; i < c.getCount(); i++) {
        str += "ID: " + c.getString(0) + "\n";
        str += "Name : " + c.getString(1) + "\n";
        str += "Location : " + c.getString(2) + "\n";
        str += "Amount : " + c.getString(3) + "\n\n";
        c.moveToNext();
    }

    Builder MyAlertDialog = new AlertDialog.Builder(this);
    MyAlertDialog.setTitle("Records");
    MyAlertDialog.setMessage(str);
    DialogInterface.OnClickListener OkClick = new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {}
    };
    MyAlertDialog.setNeutralButton("OK", OkClick);
    MyAlertDialog.show();
}