README.md

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Feature

      Shrink unnecessary or duplicate field assignment (default value) from code during compilation

Principle

      Fields in the class (including static fields and member fields) are given default values ​​by default in the memory allocated when the virtual machine is instantiated（Official Virtual Machine Specification).However, developers still often write code that assigns default initial values ​​to fields. These default value assignment instructions will be in the corresponding constructor (member field) or class code block (static field). These assignments are redundant, and the plugin will Analyze this class of assignment instructions and optimize them.
      Optimized scenarios include the following：

• Attach the default value directly where the field is declared

   private boolean aBoolean = false;
   private byte aByte = 0;
   private short aShort = 0;
   private char aChar = '\u0000';
   private int anInt = 0;
   private float aFloat = 0f;
   private double aDouble = 0d;
   private long aLong = 0l;
   private Object aObject = null;

• Make default value assignment code for fields in constructor or static block.

   class MyTestClass{
       private static int sInt;
       private int mInt;
       static {
           sInt = 0;//delete
           sInt = 0;//delete
           sInt = 1;
           sInt = 0;//not delete
           sInt = 0;//not delete
       }
       public MyTestClass(Object any){
           this();
           mInt = 0;//not delete
           sInt = 0;//not delete
       }
       public MyTestClass(){
           mInt = 0;//delete
           mInt = 0;//delete
           mInt = 1;
           mInt = 0;//not delete
           mInt = 0;//not delete
           
           sInt = 0;//not delete
           sInt = 1;//not delete
       }
   }

Quick Start

• add build classpath

  classpath "com.bytedance.android.byteX:field-assign-opt-plugin:${plugin_version}"

• apply and configure the plugin in your build.gradle(application)

   apply plugin: 'bytex.field_assign_opt'
   field_assign_opt {
           enable true
           enableInDebug false
           logLevel "INFO"
           removeLineNumber true //remove the corresponding line number information（if exist）,true is recommended。
           whiteList = [
                   //ClassName.FieldName 
                   //"android.support.constraint.solver.ArrayRow.isSimpleDefinition"
           ]
   }

Optimization Results

      More than 8000 constant fields are cut down from Douyin apk, resulting in more than 200KB slimmer than not.
      The optimized result will be printed into the corresponding app/build/ByteX/ByteX_report_ByteX.html by default.The result may look like the picture showed below: