loginActivity.java

package br.com.laborumtech.wincomanda;

import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.inputmethod.InputMethodManager;
import android.widget.EditText;

public class LoginActivity extends AppCompatActivity {

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

    EditText yourEditText= (EditText) findViewById(R.id.campoLogin);
    InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.showSoftInput(yourEditText,InputMethodManager.SHOW_IMPLICIT);

}