Question

我有一个基本功能 - 启动时 - 将查询蓝牙状态，然后使用textView指示它是否已打开。我正在使用的代码如下：

public class MainActivity extends Activity {

public final int REQUEST_ENABLE_BT = 1;
String btIsOn = "Bluetooth is On";
String btIsOff = "Bluetooth is Off";

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

    // Set the Textview
    final TextView btOn = (TextView)findViewById(R.id.btOnView);

    // Create a bluetooth Adapter
    BluetoothAdapter btAdapter;

    // BT Code
    // Check to see if BT Adapter is available
    btAdapter = BluetoothAdapter.getDefaultAdapter();

    if (btAdapter.isEnabled()){
        btOn.setText(btIsOn);
    }
    else{
        Intent btEnableIntent = new    Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(btEnableIntent, REQUEST_ENABLE_BT);

        }

    }   


@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // TODO Auto-generated method stub
    super.onActivityResult(requestCode, resultCode, data);

    // Check which request we're responding to
    if (requestCode == REQUEST_ENABLE_BT){
        // Check to see which option the user selected for BT options
        if (resultCode == RESULT_OK){
            final TextView btOn = (TextView)findViewById(R.id.btOnView);
            btOn.setText(btIsOn);
        }
        else if (resultCode == RESULT_CANCELED){
            Toast.makeText(getApplicationContext(), "Must Enable bluetooth to Use", Toast.LENGTH_SHORT).show();
            finish();
        }
    }
}

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

}

我想知道是否可以只调用textView ONE而不是多次调用textView。那可能吗？如果是这样，如何实施？感谢。

Answer 1

您可以将TextView添加为类变量：

public class MainActivity extends Activity {

  public final int REQUEST_ENABLE_BT = 1;
  String btIsOn = "Bluetooth is On";
  String btIsOff = "Bluetooth is Off";
  TextView btOn;

然后像这样在onCreate中初始化它。

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

  // Set the Textview
  btOn = (TextView)findViewById(R.id.btOnView);

这样，您可以从任何类方法访问TextView，如

btOn.setText("some text");

Answer 2

您应该全局声明文本视图batOn：

public class MainActivity extends Activity {

public final int REQUEST_ENABLE_BT = 1;
String btIsOn = "Bluetooth is On";
String btIsOff = "Bluetooth is Off";
protected TextView  btOn = (TextView) findViewById(R.id.btOnView);
...
}

试图从多种方法调用textview - Android

2 个答案: