Android获取周围WIFI热点服务

public class MainActivity extends AppCompatActivity {

  ArrayList<ScanResult> list;  //存放周围wifi热点对象的列表
  WifiManager wifiManager;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    wifiManager = (WifiManager) getSystemService(WIFI_SERVICE);  //获得系统wifi服务
    list = (ArrayList<ScanResult>)wifiManager.getScanResults();
    sortByLevel(list);
    init();
  }

  private void init(){
    TextView tv1=(TextView)findViewById(R.id.tv1);
    TextView tv2=(TextView)findViewById(R.id.tv2);
    TextView tv3=(TextView)findViewById(R.id.tv3);

    if (list.get(0).SSID != null && list.get(1).SSID != null){
      tv1.setText("信号最强为"+list.get(0).SSID);
      tv2.setText("信号第二位："+list.get(1).SSID);
      tv3.setText("共有"+list.size()+"个wifi");
    }

  }

  //将搜索到的wifi根据信号强度从强到弱进行排序
  private void sortByLevel(ArrayList<ScanResult> list) {
    for(int i=0;i<list.size();i++)
      for(int j=1;j<list.size();j++)
      {
        if(list.get(i).level<list.get(j).level)  //level属性即为强度
        {
          ScanResult temp = null;
          temp = list.get(i);
          list.set(i, list.get(j));
          list.set(j, temp);
        }
      }
  }

} 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">

  <TextView
    android:id="@+id/tv1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!" />
  <TextView
    android:id="@+id/tv2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!" />
  <TextView
    android:id="@+id/tv3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Hello World!" />
</LinearLayout>