Android读取手机通讯录联系人到自己项目

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">

  <ListView
    android:id="@+id/contacts_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

  </ListView>
</LinearLayout>

public class MainActivity extends AppCompatActivity {

  ArrayAdapter<String> adapter;

  List<String> contactsList=new ArrayList<>();

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

    //获取到listview并且设置适配器
    ListView contactsView= (ListView) findViewById(R.id.contacts_view);
    adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,contactsList);
    contactsView.setAdapter(adapter);

    //判断是否开启读取通讯录的权限
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS)!= PackageManager
        .PERMISSION_GRANTED){
      ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.READ_CONTACTS},1);
    }else {
      readContacts();
    }
  }

  private void readContacts() {
    Cursor cursor=null;
    try {
      //查询联系人数据,使用了getContentResolver().query方法来查询系统的联系人的数据
      //CONTENT_URI就是一个封装好的Uri，是已经解析过得常量
      cursor=getContentResolver().query(
          ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
          null,
          null,
          null,
          null
      );
      //对cursor进行遍历，取出姓名和电话号码
      if (cursor!=null){
        while (cursor.moveToNext()){
          //获取联系人姓名
          String displayName=cursor.getString(cursor.getColumnIndex(
              ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME
          ));
          //获取联系人手机号
          String number=cursor.getString(cursor.getColumnIndex(
              ContactsContract.CommonDataKinds.Phone.NUMBER
          ));
          //把取出的两类数据进行拼接，中间加换行符，然后添加到listview中
          contactsList.add(displayName+"\n"+number);
        }
        //刷新listview
        adapter.notifyDataSetChanged();
      }
    }catch (Exception e){
      e.printStackTrace();
    }finally {
      //记得关掉cursor
      if (cursor!=null){
        cursor.close();
      }
    }
  }

  @Override
  public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    switch (requestCode){
      case 1:
        if (grantResults.length>0&&grantResults[0]==PackageManager.PERMISSION_GRANTED){
          readContacts();
        }else {
          Toast.makeText(this,"没有权限",Toast.LENGTH_SHORT).show();
        }
        break;
      default:
        break;
    }
  }
}

<uses-permission android:name="android.permission.READ_CONTACTS"/>