Design application using more confuse code?

Recently I had opened some real apps by using this

So I'm getting the source code from that. In those source code, I found that most of the code is designed like this

public class LockActivity extends Activity {
    public void onCreate(Bundle bundle) {
        super.onCreate(bundle);
        if (GlobalDataHolder.m9617e()) {
            bm.m8771b(getApplicationContext(), getPackageManager());
            finish();
        }
    }

    protected void onResume() {
        super.onResume();
        if (GlobalDataHolder.m9617e()||this.f4719a.m9124j()) {
            bm.m8771b(getApplicationContext(), getPackageManager());

            finish();
            return;
        }
        startActivity(new Intent(getApplicationContext(), LaunchActivity.class));
    }

    public void onPause() {
        super.onPause();
    }

    public void onDestroy() {
        super.onDestroy();
    }
}

And also the java file named by Garbled text such as

aa.java

bh.java

cj.java

My question is

1) Why those developer create the function named 'm8771b','m9617e'

2) Why most of apps is designed like that?

3) Is this more secure for avoid other to copy their code?

4) Should we also design the application like that?

5) How they can remember where they put the function?