在Android中，可以使用TelephonyManager类来检测呼叫等待和第二个来电状态。下面是一个包含代码示例的解决方法：

首先，在AndroidManifest.xml文件中添加以下权限：

然后，在你的Activity或Service中添加以下代码：

import android.content.Context;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import android.util.Log;

public class CallStateListener extends PhoneStateListener {
    private static final String TAG = "CallStateListener";
    private Context context;

    public CallStateListener(Context context) {
        this.context = context;
    }

    @Override
    public void onCallStateChanged(int state, String incomingNumber) {
        super.onCallStateChanged(state, incomingNumber);
        switch (state) {
            case TelephonyManager.CALL_STATE_IDLE:
                Log.d(TAG, "Call state: IDLE");
                break;
            case TelephonyManager.CALL_STATE_RINGING:
                Log.d(TAG, "Call state: RINGING");
                break;
            case TelephonyManager.CALL_STATE_OFFHOOK:
                Log.d(TAG, "Call state: OFFHOOK");
                // 检测第二个来电状态
                TelephonyManager telephonyManager = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
                if (telephonyManager.getCallState() == TelephonyManager.CALL_STATE_RINGING) {
                    Log.d(TAG, "Second call state: RINGING");
                } else if (telephonyManager.getCallState() == TelephonyManager.CALL_STATE_OFFHOOK) {
                    Log.d(TAG, "Second call state: OFFHOOK");
                } else if (telephonyManager.getCallState() == TelephonyManager.CALL_STATE_IDLE) {
                    Log.d(TAG, "Second call state: IDLE");
                }
                break;
        }
    }
}

接下来，在你的Activity或Service中注册PhoneStateListener并监听电话状态：

import android.app.Activity;
import android.os.Bundle;
import android.telephony.TelephonyManager;

public class MainActivity extends Activity {
    private TelephonyManager telephonyManager;
    private CallStateListener callStateListener;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        telephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
        callStateListener = new CallStateListener(this);
        telephonyManager.listen(callStateListener, PhoneStateListener.LISTEN_CALL_STATE);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        telephonyManager.listen(callStateListener, PhoneStateListener.LISTEN_NONE);
    }
}

在上面的示例中，当电话状态为OFFHOOK时，我们检测第二个来电状态，并通过Log输出来显示相应的状态。你可以根据自己的需求进行进一步处理。注意在不需要监听电话状态时，要记得取消监听，以免造成资源浪费。