错误：（53 43）错误：无法找到符号变量lumn [英] Error:(53, 43) error: cannot find symbol variable lumn

问题描述

我是新来的Andr​​oid工作室和学习开发Android应用，
与上面，但无法化解它，我已经得到了一个错误。
任何形式的帮助将是AP preciated。
谢谢!!

I am new to android studio and learning to develop the android apps, I have got an error as stated above and am unable to resolve it. Any kind of help will be appreciated. Thank you!!

我ledControl.java code是如下

My ledControl.java code is as follow

package com.led.led;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.view.View;
import android.widget.Button;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.Toast;
import android.app.ProgressDialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.os.AsyncTask;

import java.io.IOException;
import java.util.UUID;


public class ledControl extends ActionBarActivity {

    Button btnOn, btnOff, btnDis;
    SeekBar brightness;
    TextView lumn;
    String address = null;
    private ProgressDialog progress;
    BluetoothAdapter myBluetooth = null;
    BluetoothSocket btSocket = null;
    private boolean isBtConnected = false;
    //SPP UUID. Look for it
    static final UUID myUUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        Intent newint = getIntent();
        address = newint.getStringExtra(DeviceList.EXTRA_ADDRESS); //receive the address of the bluetooth device

        //view of the ledControl
        setContentView(R.layout.activity_led_control);

        //call the widgtes
        btnOn = (Button)findViewById(R.id.button2);
        btnOff = (Button)findViewById(R.id.button3);
        btnDis = (Button)findViewById(R.id.button4);
        brightness = (SeekBar)findViewById(R.id.seekBar);
        lumn = (TextView)findViewById(R.id.lumn);

        new ConnectBT().execute(); //Call the class to connect

        //commands to be sent to bluetooth
        btnOn.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                turnOnLed();      //method to turn on
            }
        });

        btnOff.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v)
            {
                turnOffLed();   //method to turn off
            }
        });

        btnDis.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Disconnect(); //close connection
            }
        });

        brightness.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                if (fromUser==true)
                {
                    lumn.setText(String.valueOf(progress));
                    try
                    {
                        btSocket.getOutputStream().write(String.valueOf(progress).getBytes());
                    }
                    catch (IOException e)
                    {

                    }
                }
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });
    }

    private void Disconnect()
    {
        if (btSocket!=null) //If the btSocket is busy
        {
            try
            {
                btSocket.close(); //close connection
            }
            catch (IOException e)
            { msg("Error");}
        }
        finish(); //return to the first layout

    }

    private void turnOffLed()
    {
        if (btSocket!=null)
        {
            try
            {
                btSocket.getOutputStream().write("TF".toString().getBytes());
            }
            catch (IOException e)
            {
                msg("Error");
            }
        }
    }

    private void turnOnLed()
    {
        if (btSocket!=null)
        {
            try
            {
                btSocket.getOutputStream().write("TO".toString().getBytes());
            }
            catch (IOException e)
            {
                msg("Error");
            }
        }
    }

    // fast way to call Toast
    private void msg(String s)
    {
        Toast.makeText(getApplicationContext(),s,Toast.LENGTH_LONG).show();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_led_control, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    private class ConnectBT extends AsyncTask<Void, Void, Void>  // UI thread
    {
        private boolean ConnectSuccess = true; //if it's here, it's almost connected

        @Override
        protected void onPreExecute()
        {
            progress = ProgressDialog.show(ledControl.this, "Connecting...", "Please wait!!!");  //show a progress dialog
        }

        @Override
        protected Void doInBackground(Void... devices) //while the progress dialog is shown, the connection is done in background
        {
            try
            {
                if (btSocket == null || !isBtConnected)
                {
                    myBluetooth = BluetoothAdapter.getDefaultAdapter();//get the mobile bluetooth device
                    BluetoothDevice dispositivo = myBluetooth.getRemoteDevice(address);//connects to the device's address and checks if it's available
                    btSocket = dispositivo.createInsecureRfcommSocketToServiceRecord(myUUID);//create a RFCOMM (SPP) connection
                    BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
                    btSocket.connect();//start connection
                }
            }
            catch (IOException e)
            {
                ConnectSuccess = false;//if the try failed, you can check the exception here
            }
            return null;
        }
        @Override
        protected void onPostExecute(Void result) //after the doInBackground, it checks if everything went fine
        {
            super.onPostExecute(result);

            if (!ConnectSuccess)
            {
                msg("Connection Failed. Is it a SPP Bluetooth? Try again.");
                finish();
            }
            else
            {
                msg("Connected.");
                isBtConnected = true;
            }
            progress.dismiss();
        }
    }
}

而activity_led_control.xml是如下

And the activity_led_control.xml is as below

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context="com.led.led.ledControl">

    <TextView android:text="LED Control" android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textview2" />

    <SeekBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/seekBar"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Brightness"
        android:id="@+id/textView3"
        android:layout_above="@+id/seekBar"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="ON"
        android:id="@+id/button2"
        android:layout_above="@+id/button3"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="OFF"
        android:id="@+id/button3"
        android:layout_above="@+id/button4"
        android:layout_alignLeft="@+id/button2"
        android:layout_alignStart="@+id/button2" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Disconnect"
        android:id="@+id/button4"
        android:layout_above="@+id/textView3"
        android:layout_alignLeft="@+id/button3"
        android:layout_alignStart="@+id/button3" />

</RelativeLayout>

我知道，这个错误是在文本字段语句，但我不知道如何解决它？

I know that this error is in text field statement but i dont know how to resolve it ?

推荐答案

您没有通过 lumn 确定的TextView在 activity_led_control.xml 。

You have no TextView identified by lumn in your activity_led_control.xml.

因此​​，该行不会编译：

Therefore this line doesn't compile :

lumn = (TextView)findViewById(R.id.lumn);

因为 R.id.lumn 不产生。

您必须通过@ + ID / textview2和@ + ID / textview3确定TextViews。如果您重命名其中的一个@ + ID / lumn，您的code编译。

You have TextViews identified by "@+id/textview2" and "@+id/textview3". If you rename one of them to "@+id/lumn", your code will compile.

这篇关于错误：（53 43）错误：无法找到符号变量lumn的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！