Inexperienced learning methods to get Java Silver 11

Introduction

The author who wants to be an engineer is advised that the author has no skills in the process of job hunting and it is difficult to get a job under the current corona, and he wants to learn the skills that can be acquired one by one. With that in mind, I decided to get it from Java Silver, which I was taught.

And I just got the Java Silver 11 qualification the other day, so I would like to share the learning method up to the acquisition.

As a result, I passed with ** 89% (passing correct answer rate 63%) **: relaxed:

Target person

・ Those who are trying to acquire Java Silver for various reasons

What is Java SE certification in the first place?

This is a qualification for Java programmers conducted by Oracle. There are ** "Bronze", "Silver", and "Gold" ** as levels, and each level is proof of the current skill level.

Since I got Silver this time, I will mainly focus on the learning method of Silver.

Learning environment and learning period

The rough learning method is as above.

I would like to dig deeper from here to see what kind of learning I have done.

Learning method

I think that what I feel is important not only for Java but also for learning programming is to understand ** "why it happens" **.

For example ...

Main.java

public class Main {
  String str; // null

  public static void main(String[] args) {
    Main m = new Main();
    System.out.println(m.str); //null is output
  }
}

Another.java

public class Another {
  String str; // null

  public static void main(String[] args) {
    Main m = new Main();
    System.out.println(m.str.length()); //Run-time error(NullPointerException)
  }
}

There are two files like the one above.

It is common for both String type str to have null as the initial value.

The differences between the two files are as follows. -Main.java calls the value of ** member variable str. ** ** -In Another.java, the number of characters in the value of ** member variable str is called using a method. ** **

I won't go into details here, but if you use a method on a reference type variable that has ** null, you will get an exception called NullPointerException **.

So, Another.java uses the .length () method ** to check the number of characters for str with null, so an exception occurs.

As you can see, there are many "why" ** in programming languages. ** "Why"-> "This happens because of XX"-> "That's why this is the result!" ** If you understand it, the retention rate will increase dramatically and the degree of understanding will increase. To go.

There is no doubt that the Java learning method will be done in this way, and that's all.

You don't have to know at first when you proceed with learning, so please be aware of this.

Qualification reference book mock exam

If you learn by the above method and understand it to some extent, you can test your skills with a mock exam. The author ** has 2 laps of questions in each chapter of Kuromoto and Murasaki, and 2 laps of each of the 4 mock exams.

The standard correct answer rate is ** 63% (50 out of 80 correct answers) ** in Java Silver. I feel that there is no problem if the average correct answer rate is ** about 72% (58 out of 80 correct answers) ** in a total of 4 mock exams.

As for the ratio of reviews, ** About the contents of the mock exam ** ** Black book mock exam: Purple book mock exam = 7: 3 **, For ** commentary content **, it is recommended to reconfirm with ** black book commentary: purple book commentary = 5: 5 **.

It should be noted that ** the standard correct answer rate must be exceeded **, so ** general mistakes ** etc. are not preferable. Let's take proper measures to approach the problem.

Important problem part

Here are some of the things the author was particularly careful about when learning Java Silver.

-** Data type ** (primitive type, ** reference type ), ** type conversion , var variable --Multidimensional array - Inheritance, behavior by polymorphism ** - Difference between compile error and run-time error ** and exception handling -** Overrides and overloads ** -** Access modifier ** and final modifier -** How to handle null literals ** -** Scope **

There are other important parts, but I have listed the main ones that I was careful about. Please try to reference!

Summary

I hope it will be helpful for those who are aiming to acquire the Silver qualification from now on.

The exam fee is quite high, so be sure to go get it!

If you have any comments or questions, please contact here.