如何从另一个活动中调用whatsApp意图？

Question

我一直在为此奋斗2天，有人可以就如何解决它提出建议吗？

这是我的WhatsApp2活动......

public class WhatsApp2 extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}
public void whatsappSend(){
    try {
        String toNumber = "xxxxxxxxxx";
        Intent sendIntent = new Intent(Intent.ACTION_SENDTO,    Uri.parse("smsto:" + "" + toNumber+ "?body=" + ""));
        sendIntent.setPackage("com.whatsapp");
        startActivity(sendIntent);
    }
    catch (Exception e){
        e.printStackTrace();
    }
  }
}

我试图从另一个这样的活动中调用whatsappSend() ......

public class MainActivity extends  AppCompatActivity {
    public WhatsApp2 whatsApp2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 }

 public void whatsapp(View view) {
     whatsApp2 = new WhatsApp2();
     whatsApp2.whatsappSend();
  }
 }

它在WhatsApp2类中的Catch异常错误如下：

java.lang.NullPointerException：尝试在空对象引用上调用虚方法'android.app.ActivityThread $ ApplicationThread android.app.ActivityThread.getApplicationThread（）'

Answer 1

**Try this if you want call whatsapp method from another activity**
//MainActivity



public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); 
        Whatspp send=new Whatspp(this);
        send.whatsappSend();
    }



}
//Whatspp Class

public class Whatspp  {
    Context _cContext;

    public Whatspp(MainActivity mainActivity) {
        _cContext=mainActivity;
    }

    void whatsappSend() {
        try {
            String toNumber = "**********";
            Intent sendIntent = new Intent(Intent.ACTION_SENDTO, Uri.parse("smsto:" + "" + toNumber + "?body=" + ""));
            sendIntent.setPackage("com.whatsapp");
            _cContext.startActivity(sendIntent);
        } catch (Exception e) {
            Log.i("TAG", "whatsappSend: "+e.getMessage());
            e.printStackTrace();
        }

    }
}