startActivityForResult(new Intent(YourActivity.this, CaptureActivity.class), CaptureActivity.REQ_CODE)

package com.acker.simplezxing.demo;

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import com.acker.simplezxing.activity.CaptureActivity;

public class MainActivity extends AppCompatActivity {

    private static final int REQ_CODE_PERMISSION = 0x1111;
    private TextView tvResult;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tvResult = (TextView) findViewById(R.id.tv_result);
        Button btn = (Button) findViewById(R.id.btn_sm);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // Open Scan Activity
                if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                    // Do not have the permission of camera, request it.
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CAMERA}, REQ_CODE_PERMISSION);
                } else {
                    // Have gotten the permission
                    startCaptureActivityForResult();
                }
            }
        });
    }

    private void startCaptureActivityForResult() {
        Intent intent = new Intent(MainActivity.this, CaptureActivity.class);
        Bundle bundle = new Bundle();
        bundle.putBoolean(CaptureActivity.KEY_NEED_BEEP, CaptureActivity.VALUE_BEEP);
        bundle.putBoolean(CaptureActivity.KEY_NEED_VIBRATION, CaptureActivity.VALUE_VIBRATION);
        bundle.putBoolean(CaptureActivity.KEY_NEED_EXPOSURE, CaptureActivity.VALUE_NO_EXPOSURE);
        bundle.putByte(CaptureActivity.KEY_FLASHLIGHT_MODE, CaptureActivity.VALUE_FLASHLIGHT_OFF);
        bundle.putByte(CaptureActivity.KEY_ORIENTATION_MODE, CaptureActivity.VALUE_ORIENTATION_AUTO);
        bundle.putBoolean(CaptureActivity.KEY_SCAN_AREA_FULL_SCREEN, CaptureActivity.VALUE_SCAN_AREA_FULL_SCREEN);
        bundle.putBoolean(CaptureActivity.KEY_NEED_SCAN_HINT_TEXT, CaptureActivity.VALUE_SCAN_HINT_TEXT);
        intent.putExtra(CaptureActivity.EXTRA_SETTING_BUNDLE, bundle);
        startActivityForResult(intent, CaptureActivity.REQ_CODE);
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case REQ_CODE_PERMISSION: {
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    // User agree the permission
                    startCaptureActivityForResult();
                } else {
                    // User disagree the permission
                    Toast.makeText(this, "You must agree the camera permission request before you use the code scan function", Toast.LENGTH_LONG).show();
                }
            }
            break;
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode) {
            case CaptureActivity.REQ_CODE:
                switch (resultCode) {
                    case RESULT_OK:
                        tvResult.setText(data.getStringExtra(CaptureActivity.EXTRA_SCAN_RESULT));  //or do sth
                        break;
                    case RESULT_CANCELED:
                        if (data != null) {
                            // for some reason camera is not working correctly
                            tvResult.setText(data.getStringExtra(CaptureActivity.EXTRA_SCAN_RESULT));
                        }
                        break;
                }
                break;
        }
    }
}