一个简单的yii2函数不起作用

Question

我有两个功能，它们具有相同的目的，但我的写法不同。第一个工作正常，但第二个工作正常 - 但是我无法看到它们之间的区别。有人可以解释为什么第二个不能正常工作吗？

1. public class SplashActivity extends Activity {
   
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
       requestWindowFeature(Window.FEATURE_NO_TITLE);
       setContentView(new SplashEnvironment(this, this));
       new Handler().postDelayed(new Runnable() {
   
       /*
        * Showing splash screen with a timer. This will be useful when you
        * want to show case your app logo / company
        */
   
       @Override
       public void run() {
           startActivity(new Intent(SplashActivity.this, MainActivity.class));
           finish();
           // close this activity
       }
   }, 3000);// time for spalsh screen
   }
   

2. public function getClientPhone()
   {
   if (is_null($this->client_id)) {
       return '';
   }
   
   $phone = Client::getStaticClientPhone($this->client_id);
   
   if (is_null($phone)) {
       return '' ;
   }
   
   return $phone;
   }
   

Answer 1

更改

if ($this->client_id || $phone === null) {
    return '';
}

要

if ($this->client_id === null || $phone === null) {
    return '';
}

或者

if (!$this->client_id || $phone === null) {
     return '';
}