public class RegisterActivity extends AppCompatActivity {

    private ImageView iv;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_register);

        iv = (ImageView) findViewById(R.id.iv_hand);

        iv.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                Intent intent = new Intent(Intent.ACTION_PICK,null);

                intent.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,"image/*");

                startActivityForResult(intent,100);

            }

        });

    }

    @Override

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {

        super.onActivityResult(requestCode, resultCode, data);

        if (resultCode == RESULT_OK && requestCode == 100) {

            if (data != null) {

                iv.setImageURI(data.getData());

            }

        }

    }

}