[Java] Learning methods that no one has done to get Java Silver 11

4 minute read

Introduction

The author who is aspiring to be an engineer received advice that the author has no skills in the process of job hunting, and it is difficult to find a job under the current corona, so I will learn from the ability to wear skills one by one. First of all, I decided to get it from Java Silver that you taught me.

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

As a result, I was able to pass with ** 89% (passed correct answer rate 63%) **: relaxed:

Target

・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 provided by Oracle Corporation. There are Bronze”, “Silver” and “Gold” as levels, and each level will prove the level of the current skill.

Level Overview
Bronze Basic level of object-oriented programming using Java language
Silver ** A level at which you have the basic programming knowledge required for Java application development and can perform development work under the guidance of an advanced person**
Gold Skills that correctly understand the designer’s intention and can implement functions by themselves

Since I acquired Silver this time, I will focus on how to learn Silver.

Learning environment and period

|| Language Learning | Qualification Learning | |:—-:|:—-:|:—-:| | Period | Approximately one month | Approximately one month | | Usage Reference | “Introduction to Java”[``Self-studyJava]](https://www.amazon.co.jp/%E7%8B%AC%E7%BF%92Java-%E6%96%B0%E7%89%88-%E5%B1%B1%E7%94%B0-%E7%A5%A5%E5%AF%9B-ebook/dp/B07PY43SL2/ref=sr_1_1?__mk_ja_JP=%E3%82%AB%E3%82%BF%E3%82%AB%E3%83%8A&crid=39L6NBVSQL974&dchild=1&keywords=%E7%8B%AC%E7%BF%92java&qid=1595649211&sprefix=dokusyuu%2Caps%2C270&sr=8-1)|”black book” “purple book”| |Learning method |** Understand the basic parts with “Clear Java Introduction”, and re-understand with “self-study Java” and absorb as supplementary knowledge. |** Read the explanation carefully and learn how to approach the correct answer to the problem. **|

The rough learning method is as described above.

I would like to dig down from here and see what kind of learning I have done specifically.

Learning method

I think that what is important as a learning method not only for Java but also for programming is understanding “how and why”.

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 as above.

It is common to both that string type str has null as the initial value.

The differences between the two files are as follows.

  • In Main.java, the value of the member variable str is called. **
  • 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, an exception NullPointerException will occur.

Therefore, Another.java uses the length() method for checking the number of characters in str that has null, so an exception occurs.

As you can see, there are many things in programming languages that are “why”. Understanding with the feeling “why” → “this is the reason for ○○” → “so this is the result!”, the retention rate will increase dramatically, and the understanding will increase To go.

There is no doubt that the Java learning method will be done in this way, and it will be exhausted.

Be aware of this as you don’t have to know it when you start learning.

Examination of qualification reference book

If you have learned the above method and have been able to understand it to a certain extent, you can try your skills by imitation. The author included two laps of each of the black and purple book chapters, and two laps each, so a total of four laps each had two laps.

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

As for the ratio of review, regarding contents of **imitation, imitation of black book: imitation of purple book = 7:3, Regarding contents, it is recommended that you reconfirm with “Blackbook commentary: Purple book commentary = 5: 5**”.

It is important to note that the standard correct answer rate must be exceeded, so errors are not desirable. Let’s take proper measures to approach the problem.

Important problem part

Here are some of the things the author has specifically noticed when learning Java Silver.

  • ** data type ** (primitive type, ** reference type **), ** type conversion **, var variable
  • Multidimensional array
  • Inheritance, polymorphism behavior
  • Difference between compilation error and runtime error and exception handling
  • ** Overrides and Overloads **
  • Access modifier and final modifier
  • Handling null literals
  • Scope

There are other important parts as well, but I’ve listed the ones that I’ve mainly noted. Please try to reference!

Summary

We hope that it will be useful for those who are aiming to acquire Silver certification.

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

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