Rule Definition
On of the fundamental concept of this rule is encapsulation: Hiding the internals of the object protects its integrity by preventing users from setting the internal data of the component into an invalid or inconsistent state. A benefit of encapsulation is that it can reduce system complexity, and thus increases robustness, by allowing the developer to limit the interdependencies between software components.

Remediation
Implement and use accessors ( getter/setter methods ) to access non-static-final fields from other classes.

Violation Code Sample

// com/test/A.java  package com.test;  import java.awt.Insets;  class B{     public String s;     public static final Integer i = 10; }  public class A {          void metdhodAccessedByField() {         B b = new B();         b.s.concat(""); // VIOLATION - DIRECT FIELD ACCESS OF ANOTHER CLASS DURING METHOD CALL     }          void publicFieldOtherClass() {         B b = new B();         b.s = ""; // VIOLATION - DIRECT FIELD ACCESS OF ANOTHER CLASS     }          void staticFinalField() {         Integer x = B.i;  // NO VIOLATION - ACCESS OF STATIC FINAL FIELD     } }  class C {     public int a;     class D {         private float x;         class E {             void outerClassField () {                 x=10.0f;    // NO VIOLATION - ACCESSING OUTER CLASS FIELD             }                          void recursiveOuterClassField () {                 a=10;        // NO VIOLATION - ACCESSING OUTER CLASS FIELD             }         }     } }  class F{     static class G {         static char c = 'x';         static class H {             static boolean b;         }     }          void innerClassField() {         G.c = 'c';  // NO VIOLATION - ACEESSING INNERCLASS FIELD     }          void recursiveInnerClassField() {         G.H.b = true; // NO VIOLATION - ACCESSING INNERCLASS FIELD     }      }  class I {     double d; }  class J extends I {     void baseClassField() {         d = 20.0; // NO VIOLATION - ACCESSING BASE CLASS FIELD     } }  class K {     byte b;     void sameClassField() {         b=1;     // NO VIOLATION - ACCESSING SAME CLASS FIELD     } }  class L extends java.awt.Insets {      public L(int t, int l, int b, int r) {         super(t, l, b, r);     }      private static final long serialVersionUID = 1L;          void randomMethod(int x) {}          void externalBaseClassMethodArgField() {         randomMethod(top); // NO VIOLATION - METHOD ARG IS A FIELD FROM BASE CLASS     }          int externalClassFieldReturn() {         return right;    // NO VIOLATION - RETURNING VALUE IS A FIELD FROM BASE CLASS              } }

Fixed Code Sample

// com/test/A.java  package com.test;  import java.awt.Insets;  class B{     private String s;     public  static final Integer i = 10;      public String getS(){ return s; }     public void setS( String t ) { s = t; } }  public class A {          void metdhodAccessedByField() {         B b = new B();         b.getS().concat(""); // NOT A VIOLATION ANYMORE - USING GETTER TO GET THE FIELD     }          void publicFieldOtherClass() {         B b = new B();         b.setS( "" ); // NOT VIOLATION ANYMORE - USING SETTER TO SET THE FIELD     }          // ... }  // ...