Primitive Data Types

• byte

• short

• int

• long

• float: ~6-7 decimal digits

• double: 15 decimal digits

• char: surrounded by single quotes

• boolean

Notes:

1. End the value with an "f" for floats and "d" for doubles

Non-Primitive Data Types

• String (object): surrounded by double quotes

Methods

length(), toUpperCase(), toLowerCase(), indexOf(), concat() or +, see more here.

Notes:

1. Non-primitive types can be used to call methods to perform certain operations, while primitive types cannot.

2. A primitive type has always a value, while non-primitive types can be null.

3. If you add a number and a string, the result will be a string concatenation.

Java Array

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
for (int i = 0; i < cars.length; i++) {
  System.out.println(cars[i]);
}

or,

int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };

Java Class

Math

min(), max(), abs(), random() see more here.

ArrayList

The ArrayList class is a resizable array.

Methods

add(), get(), set(), remove(), clear(), size() Use Collections for sorting lists alphabetically or numerically.

import java.util.ArrayList;
import java.util.Collections;  // Import the Collections class

public class Main {
  public static void main(String[] args) {
    ArrayList<Integer> myNumbers = new ArrayList<Integer>();
    myNumbers.add(33);
    myNumbers.add(15);
    myNumbers.add(20);
    myNumbers.add(34);
    myNumbers.add(8);
    myNumbers.add(12);

    Collections.sort(myNumbers);  // Sort myNumbers

    for (int i : myNumbers) {
      System.out.println(i);
    }
  }
}

Notes

1. Elements in an ArrayList are actually objects. In the examples above, we created elements (objects) of type "String". Remember that a String in Java is an object (not a primitive type). To use other types, such as int, you must specify an equivalent wrapper class: Integer. For other primitive types, use: Boolean for boolean, Character for char, Double for double, Float for float, etc.

LinkedList

The LinkedList class has all of the same methods as the ArrayList class because they both implement the List interface.

Difference

• The ArrayList class has a regular array inside it. When an element is added, it is placed into the array. If the array is not big enough, a new, larger array is created to replace the old one and the old one is removed.

• The LinkedList stores its items in "containers." The list has a link to the first container and each container has a link to the next container in the list. To add an element to the list, the element is placed into a new container and that container is linked to one of the other containers in the list.

• Use an ArrayList for storing and accessing data, and LinkedList to manipulate data.

Methods

addFirst(), addLast(), removeFirst(), removeLast(), getFirst(), getLast()

HashMap

A HashMap however, store items in "key/value" pairs, and you can access them by an index of another type.

Methods

put(), get(), remove(), clear(), size(), keySet(), values()

// Import the HashMap class
import java.util.HashMap;

public class Main {
  public static void main(String[] args) {
    // Create a HashMap object called capitalCities
    HashMap<String, String> capitalCities = new HashMap<String, String>();

    // Add keys and values (Country, City)
    capitalCities.put("England", "London");
    capitalCities.put("Germany", "Berlin");
    capitalCities.get("England");
    capitalCities.remove("England");
    for (String i : capitalCities.keySet()) {
      System.out.println(i);
    }
  }
}

HashSet

A HashSet is a collection of items where every item is unique.

Methods

add(), contains(), remove(), clear(), size()

// Import the HashSet class
import java.util.HashSet;

public class Main {
  public static void main(String[] args) {
    HashSet<String> cars = new HashSet<String>();
    cars.add("Volvo");
    cars.add("BMW");
    cars.add("Ford");
    for (String i : cars) {
      System.out.println(i);
    }
  }
}

Iterator

An Iterator is an object that can be used to loop through collections, like ArrayList and HashSet.

Methods

hasNext(), next(), remove()

import java.util.ArrayList;
import java.util.Iterator;

public class Main {
  public static void main(String[] args) {
    ArrayList<Integer> numbers = new ArrayList<Integer>();
    numbers.add(12);
    numbers.add(8);
    numbers.add(2);
    numbers.add(23);
    Iterator<Integer> it = numbers.iterator();
    while(it.hasNext()) {
      Integer i = it.next();
      if(i < 10) {
        it.remove();
      }
    }
    System.out.println(numbers);
  }
}

Enums

An enum is a special class, cannot be used to create objects.

enum Level {
  LOW,
  MEDIUM,
  HIGH
}
Level myVar = Level.MEDIUM;

for (Level myVar : Level.values()) {
  System.out.println(myVar);
}

Class Inheritance

1. To inherit from a class, use the extends keyword.

2. Java does not support "multiple inheritance" (a class can only inherit from one superclass). However, it can be achieved with interfaces, because the class can implement multiple interfaces. Note: To implement multiple interfaces, separate them with a comma.

interface FirstInterface {
  public void myMethod(); // interface method
}

interface SecondInterface {
  public void myOtherMethod(); // interface method
}

class DemoClass implements FirstInterface, SecondInterface {
  public void myMethod() {
    System.out.println("Some text..");
  }
  public void myOtherMethod() {
    System.out.println("Some other text...");
  }
}

Java If ... Else

Syntax:

if (condition1) {
  // block of code to be executed if condition1 is true
} else if (condition2) {
  // block of code to be executed if the condition1 is false and condition2 is true
} else {
  // block of code to be executed if the condition1 is false and condition2 is false
}

Java Switch

Syntax:

int day = 4;
switch (day) {
  case 6:
    System.out.println("Today is Saturday");
    break;
  case 7:
    System.out.println("Today is Sunday");
    break;
  default:
    System.out.println("Looking forward to the Weekend");
}
// Outputs "Looking forward to the Weekend"

Java For Each Loop

Used exclusively to loop through elements in an array

Syntax:

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};
for (String i : cars) {
  System.out.println(i);
}

Java Lambda Expressions

A lambda expression is a short block of code which takes in parameters and returns a value. Lambda expressions are similar to methods, but they do not need a name and they can be implemented right in the body of a method.

Syntax

(parameter1, parameter2) -> { code block }

import java.util.ArrayList;

public class Main {
  public static void main(String[] args) {
    ArrayList<Integer> numbers = new ArrayList<Integer>();
    numbers.add(5);
    numbers.add(9);
    numbers.add(8);
    numbers.add(1);
    numbers.forEach( (n) -> { System.out.println(n); } );
  }
}

Java Regular Expressions

Use java.util.regex package to work with regular expressions. The package includes the following classes:

• Pattern Class - Defines a pattern (to be used in a search)

• Matcher Class - Used to search for the pattern

• PatternSyntaxException Class - Indicates syntax error in a regular expression pattern

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
  public static void main(String[] args) {
    Pattern pattern = Pattern.compile("w3schools", Pattern.CASE_INSENSITIVE);
    Matcher matcher = pattern.matcher("Visit W3Schools!");
    boolean matchFound = matcher.find();
    if(matchFound) {
      System.out.println("Match found");
    } else {
      System.out.println("Match not found");
    }
  }
}

Java Exception

Use try, catch, finally:

public class Main {
  public static void main(String[] args) {
    try {
      int[] myNumbers = {1, 2, 3};
      System.out.println(myNumbers[10]);
    } catch (Exception e) {
      System.out.println("Something went wrong.");
    } finally {
      System.out.println("The 'try catch' is finished.");
    }
  }
}

Java Packages

A package in Java is used to group related classes.

Import a class

import java.util.Scanner;

Import a whole package

import java.util.*;

1. 设置群控，就是在本地电脑上同时打开多个浏览器窗口，每个窗口模拟一个独立的用户，窗口之间保持独立，没有关联，包括IP，cookie，浏览痕迹等。并且可以通过控制一个主控窗口同时操控其他的被控窗口，同时进行多个窗口的操作。

2. 进行撸毛，还需要每个浏览器窗口都有email，twitter，discord 和metamask等必备件。

   以下分别进行介绍：

设置群控

如上所述，我们需要批量的IP，能够同时打开多个窗口并且彼此独立的浏览器，以及群控软件。

IP池

当然需要使用海外IP，并且尽量选择监管少的国家，新加坡、澳洲、欧洲（俄罗斯除外）是相对来说比较宽松的。北美其实也可以，不过有风险某些项目会不支持。可以选择搭建或购买一个IP群服务器，也可以直接购买批量IP。各有很多选择，我在 proxy6.net上买了50个，并且支持加密货币支付。并且尽量选择独立IP。你会得到卡密，类似 [IP]:[port]:[user]:[pswd]，之后使用。

https://proxy6.net/en/?r=454388

指纹浏览器

需要使用指纹浏览器实现同时打开多个窗口，这里也有很多选择，比特浏览器为免费，并且最近刚刚集成了群控软件；adspower为付费，需要另外购买群控软件。我都试过，感觉都不完美，不同步的情况时有发生。相比来说，adspower稍微好一点点。。购买好后，试着批量创建窗口，并且把上一步的IP分配给这些窗口，一对一。此时你就拥有了批量的独立窗口。

https://adspower.saaslink.net/MJKBeGQDORS6sZj

群控器

没有群控器，你就需要手动一个一个操作你刚刚批量创建的窗口，无疑非常费时间。可以去taobao搜索麒麟群控器选择购买。注意，只支持windows电脑，Mac版暂无软件。有了群控器，你就可以批量操作，比如批量排列窗口，打开窗口，浏览网页，鼠标点击、键盘输入等等。你需要首先选择主控窗口，软件就会自动识别你批量打开的其他窗口，并且设置为被控窗口。注意对于像metamask弹出的这种窗口，你需要重新把弹出的窗口选择为主控窗口，你才可以批量操作metamask的弹窗。因为弹出的窗口和浏览器窗口为不同的句柄窗口。

批量撸毛必备件

接下来就是准备撸毛用的一些软件，必不可少的就是gmail，twitter（直接用gmail账户登陆）、discord和metamask。 metamask是最容易创建的，只需要去指纹浏览器的应用中心设置安装chrome store的metamask插件，就可以自动的为你创建的每一个窗口安装插件，然后每个选择创建新钱包、地址，注意保存seed phrase。不要在这些地址之间频繁/批量转账，使用CEX直接向每个地址转账。

Gmail

首先可以选择批量购买gmail。你也可以选择自己一个一个创建，不过除了需要recovery email还有手机验证。建议你先自己创建几个email账户作为recovery email使用，这些email要拥有绝对控制权，包括密保邮箱和手机号等。大概一个recovery email可以被多个email当作密保邮箱（至少十个应该没问题）。手机验证的话，一般一个手机号不能短时间注册多个email，这时需要使用接码平台。选择也很多，我使用 5sim.net，也支持加密货币支付。注意你需要去尝试不同的国家和operator，并不能保证每个号都可以接到码，没收到码的可以退款。自己创建的使用要在指纹浏览器中进行，每个窗口分别进行，保证相对独立；

https://5sim.net/

如果选择购买邮箱，可以网上搜索，很多选择，注意先购买一个试试。有的号不好的话一登陆就会封。我使用0x90000.com，可以尽量选择你购买IP地址国家的google号，并且选择那些已经手机验证过的、有密保邮箱的。登陆的时候，一般都需要进行验证，可以选择输入密保邮箱地址进行验证，登陆后及时修改密码和你的密保邮箱。

https://www.0x90000.com/

Twitter

直接可以使用google账户创建登陆。坏处是是新号，极容易被封控进行人机验证。一般创建好后，用一会就回要求人机验证。注意刚开始尽量每个窗口都交互一下，包括关注、转发、点赞和发推，并且分别操作。等第二天登陆的时候我的账户又被要求验证，并且还需要手机验证，这时候就需要再次用到接码平台。通过后在进行交互。一般通过这一步以后就会好很多，不会再被封控，但还是要平时多多养号。

Discord

不知道为什么，我无法接到discord发送的手机验证码，所以无奈我选择批量购买discord账户。当时我选择的是在https://bffkd.com/links/7E279C1B上购买的，注意你需要使用国内IP才能打开这个网址。购买后你会得倒账户密码和一个token。如果你选择账户密码登陆，大概率会被要求验证手机号，所以推荐token登陆。登陆方法为，在 discord.com/login 页面，代开后台，或者按F12，点到console页面，复制下面代码，注意替换成你自己的token，然后回车。等几秒后，如果正常你就会登进去。如果还是卡在登陆界面，大概率账号有问题，被ban了。

function login(token) { setInterval(() => { document.body.appendChild(document.createElement `iframe`).contentWindow.localStorage.token = `"${token}"` }, 50); setTimeout(() => { location.reload(); }, 2500); } login(“你的token”);

注意登陆进去后不要删除密保手机，保持现状正常交互即可。

最后

刚开始多账号撸毛最麻烦的其实是养号，特别是twitter和discord，要多多进行交互并且保持各个账号独立。另外注意IP和你的账号要对应起来，以后不要随便带动，否则新IP登陆容易风控。祝撸毛顺利！