I joined Ali P8 at the so-called age of 35+ and never left the front line for more than ten years. At the same time, as a certified interviewer in a large factory, I have seen various candidates in the actual recruitment process, and their failures and successes can give you some reference.

Share some interview questions I examined in the interview, for detailed analysis, you can also go to my lecture “Java Senior Engineer” free audition.

Java backend 3, undergraduate school recruit come in, very outstanding young man.

What is the difference between the JDK and the JRE?

A: Specifically, the JDK actually contains the JRE, as well as the compiler Javac that compiles Java source code, as well as a number of tools for debugging and analyzing Java programs. Simply put: if you need to run Java programs, just install the JRE, and if you need to write Java programs, install the JDK.

Q: What other command-line tools do you know about besides Javac, and what are they used for?

Jcmd: A comprehensive tool

JPS: tool for vm process status

Jinfo jstat: monitors vm statistics

Jinfo: Java configuration information tool

Jmap: Java memory mapping tool

Jhat: vm heap dump snapshot analysis tool

Jstack: Java stack tracing tool

Follow-up: Ever used Jstat? What parameters do you know?

…

In fact, these questions are not difficult to separate, mainly to have a deep understanding of the technical stack and principle, into a system, into a structure, in the face of the in-depth questioning of the interviewer to answer in an orderly manner.

At this point, you can almost pass.

Java second surface, working for 3 years veteran, technology is not very solid

This little brother’s answer is not very good, I directly put the “reference answer” for you.

Q: What is the difference between equals and equals?

** Key points of the answer: ** Both methods are equivalent. They differ in terms of “primitive types”, which compare values, and “reference types”, which compare whether they are the same object.

** Primitives & reference types

Basic type: Compares whether the values are the same

Reference type: Compares whether references are the same

The native implementation of equals() defines the relationship between them directly:

Plus Tips:

Of course, we can override the equals method in Oblect to implement a custom equivalent calculation. For example, in the case of String, since the method is re-implemented in the source code, the following result is produced:

The contents of strings instantiated with String constants are kept in the constants section

String x = “string”;

String y = “string”;

X = = y – > true

All references to the same data item in the constant area, hence the above result

** Check point: **equals() concept

** Practical requirements: ** usually on the source of deep awareness of technical research and critical thinking

The above questions have the following characteristics:

1. They are textbook level topics

2, are commonly used in engineering practice

Are accustomed to, not easy to take the initiative to explore

Investigation Purpose:

1. The solid degree of basic knowledge

2. The candidate’s passion for technology

More Java interview knowledge and inspection methods, I in the “Java senior engineer P6+” in the lecture very clear, interested students can click on the free trial experience.

Wish you become a qualified Java engineer ~