Java 无法在Android中获取主机地址

我正在创建一个Android应用程序。这里我需要得到Android设备的IP地址。下面是我的主要活动代码

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.text.format.Formatter;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.TextView;

import java.math.BigInteger;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.nio.ByteOrder;

public class MainActivity extends AppCompatActivity {
Button button;
TextView txtView;
public static Context context = MyApplication.getAppContext();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    addListenerOnButton();
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });
}

public void addListenerOnButton() {

    button = (Button) findViewById(R.id.button_ip);

    button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {
            WifiManager wifiManager = (WifiManager) getSystemService(WIFI_SERVICE);
            WifiInfo wifiInfo = wifiManager.getConnectionInfo();
            int ipAddress = wifiInfo.getIpAddress();
            if (ByteOrder.nativeOrder().equals(ByteOrder.LITTLE_ENDIAN)) {
                ipAddress = Integer.reverseBytes(ipAddress);
            }

            byte[] ipByteArray = BigInteger.valueOf(ipAddress).toByteArray();

            String ipAddressString;
            try {
                ipAddressString = InetAddress.getByAddress(ipByteArray)
                        .getHostAddress();
            } catch (UnknownHostException ex) {
                Log.e("WI-Resource", "Unable to get host address.");
                ipAddressString = null;
            }
            System.out.println(ipAddress);
                //txtView.setText(ipAddress);

        }

    });

}

@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_main, 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);
}
}

在我的设备中创建WiFi热点后，我启动了应用程序，然后它出现以下异常：

Unable to get host address

有谁能帮我解决这个问题吗？

试试这个

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