单击按钮时将用户输入字符串保存到变量中

Question

在我的应用程序中，用户将在可编辑的文本字段中输入他们想要订阅的频道。单击订阅按钮后，放置在我的方法中用于订阅用户的变量应该更新为用户选择的变量，然后会出现一个toast，通知用户他们订阅了该频道。

在底部，我得到了用户在EditText字段中输入的字符串值，但我认为我没有把它放在正确的位置。有人能看看它，让我知道我做错了什么吗？如果我不清楚或遗漏了什么，请告诉我，我可以试着更好地解释。谢谢

public class MainActivity extends ActionBarActivity {
private Button channelSubscribeButton;
private EditText subscribeChannelEditText;
//Declare variable
String subscribeChannel = null;

//-------------------------Access PubNub API-------------------------//
Pubnub pubnub = new Pubnub("pub-c-940c4776-36ff-425f-9677-f1c904a9d57b", "sub-c-cf42b292-a8bf-11e4-85d5-0619f8945a4f");

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    channelSubscribeButton = (Button) findViewById(R.id.subscribe_button);
    subscribeChannelEditText = (EditText) findViewById(R.id.channel_name);

    //-------------------------Subscribe to a Channel to Receive Messages-------------------------//

    try {
//THIS IS WHERE I AM INPUTTING THE VARIABLE THAT CONTAINS THE USER INPUTTED TEXT//
//I AM GETTING ERROR THAT SAYS IT CAN'T RESOLVE THE SYMBOL 'subscribeChannel'//
        pubnub.subscribe(subscribeChannel, new Callback() {
                    @Override
                    public void connectCallback(String channel, Object message) {
                        Log.d("PUBNUB", "SUBSCRIBE : CONNECT on channel:" + channel
                                + " : " + message.getClass() + " : "
                                + message.toString());
                    }
                    @Override
                    public void disconnectCallback(String channel, Object message) {
                        Log.d("PUBNUB", "SUBSCRIBE : DISCONNECT on channel:" + channel
                                + " : " + message.getClass() + " : "
                                + message.toString());
                    }
                    public void reconnectCallback(String channel, Object message) {
                        Log.d("PUBNUB", "SUBSCRIBE : RECONNECT on channel:" + channel
                                + " : " + message.getClass() + " : "
                                + message.toString());
                    }
                    @Override
                    public void successCallback(String channel, Object message) {
                        Log.d("PUBNUB", "SUBSCRIBE : " + channel + " : "
                                + message.getClass() + " : " + message.toString());
                    }
                    @Override
                    public void errorCallback(String channel, PubnubError error) {
                        Log.d("PUBNUB", "SUBSCRIBE : ERROR on channel " + channel
                                + " : " + error.toString());
                    }
                }
        );
    } catch (PubnubException e) {
        Log.d("PUBNUB", e.toString());
    }
public void onChannelButtonClick(View view) {
    subscribeChannel = String.valueOf(subscribeChannelEditText.getText());
    String yourSubscribeChannel = "Subscribed to the " + subscribeChannel + " Channel";
    Toast.makeText(this, yourSubscribeChannel, Toast.LENGTH_LONG).show();
    return subscribeChannel;
}

Answer 1

subscribeChannel变量仅在onChannelButtonClick方法的范围内可见。在外部将其与实例变量一起声明。

public void onChannelButtonClick(View view) {    
    //here you set it and then it's lost.
    String subscribeChannel = String.valueOf(subscribeChannelEditText.getText());    
    String yourSubscribeChannel = "Subscribed to the " + subscribeChannel + " Channel";    
    Toast.makeText(this, yourSubscribeChannel, Toast.LENGTH_LONG).show();    
}

相反：

//declare it.
String subscribeChannel = null;

然后在你的方法上赋值。

public void onChannelButtonClick(View view) {    
    //assign it.
    subscribeChannel = String.valueOf(subscribeChannelEditText.getText());    
    String yourSubscribeChannel = "Subscribed to the " + subscribeChannel + " Channel";    
    Toast.makeText(this, yourSubscribeChannel, Toast.LENGTH_LONG).show();    
}