title: Cannot find symbol error in Test Class
body: <p>This is my student class.</p>
  
  <pre><code>public class Student {
      private String name;
      private long id;
      private double gpa;
      private PersonalData pd;
  
      public Student(String name, long id, double gpa, PersonalData pd){
          this.name= name;
          this.id=id;
          this.gpa= gpa;
          this.pd= pd;
      }
  
      public String getName(){
          return name;
      }
  
      public long getID(){
          return id;
      }
  
      public double getGPA(){
          return gpa;
      }
  
      public PersonalData getPersonalData(){
          return pd;
      }
  
      public String toString(){
          String result= "Name: "+ name+ ", ID: "+ id+ ", GPA: "+gpa+", Personal Data: "+ pd;
          return result;
      }
  }
  </code></pre>
  
  <p>Here is the test class:</p>
  
  <pre><code>public class Test {
  
      public static void main(String[] args) {
  
          // TODO, add your application code
          PersonalData a= new PersonalData(80,4,1,1232154687);
          Student b= new Student(Ali,123,20,a);
      }
  }
  </code></pre>
  
  <p>It gives this error:</p>
  
  <pre><code>cannot find symbol
          Student b= new Student(Ali,123,20,a);
                                 ^
    symbol:   variable Ali
    location: class Test
  1 error
  </code></pre>
  
  <p>I don't know what is wrong. Is there anyone can see?</p>