Question

我正在使用父类具有SparseArray private static nested class的设计。现在，如果我尝试使用GSON库对父对象进行jsonify，它是否能够对我的父类对象进行jsonify和de-jsonify，因为嵌套类实际上在外部不可见。代码看起来像这样。

class A {
  private SparseArray<B> array = new SparseArray<B>();

  private A() {}

  private static class B {
    private B() {}
    int example;
  }
  // static public accessors to access some methods of class A, no object of A outside A
}

我的另一个方面是我不希望任何人在外面创建父类的对象，所以我将默认构造函数保持为私有。我想知道GSON在我的代码场景中是否会正常运行。

将其转换为JSON后，SparseList内的对象似乎转换为null而不是jsonified对象。

Answer 1

通过使用此测试类找到答案，得出GSON与每个可见性修饰符无缝地工作，无论是公共还是私有，无论是类，方法，实例变量还是构造函数。我得到的错误是由于SparseArray的使用，如果它被替换为HashMap，如下所示就像黄油一样。

package in.mubble.mubbletest;

import java.util.HashMap;

import android.annotation.SuppressLint;
import android.util.Log;

@SuppressLint("UseSparseArrays")
@SuppressWarnings("unused")
public class GSONTest {

  private HashMap<Integer, B> myMap;
  private String extra;

  private GSONTest() {
    Log.e("GSONTest", "default constructor GSONTEST was called");
  }

  public GSONTest(String extra) {
    myMap      = new HashMap<Integer, B>(); 
    this.extra = extra;
    myMap.put(1, new B(7));
    Log.e("GSONTest", "parameter constructor GSONTEST was called");
  }

  private static class B {
    int child;
    private B() {
      Log.e("B", "default constructor B was called");
    }

    private B(int child) {
      Log.e("B", "parameter constructor B was called");
      this.child = child;  
    }
  }

  public String toString() {
    return this.myMap.size() + ": " + this.extra + ", " + this.myMap.get(1).child;
  }

}

带有测试代码

GSONTest test = new GSONTest("hahaha");
Gson gson     = new Gson();    
String json   = gson.toJson(test);
Log.e("json", json);
GSONTest result = gson.fromJson(json, GSONTest.class);
Log.e("result", result.toString());

运行时此代码在logcat上生成此输出

parameter constructor B was called
parameter constructor GSONTEST was called
{"extra":"hahaha","myMap":{"1":{"child":7}}}
default constructor GSONTEST was called
default constructor B was called
1: hahaha, 7

GSON可以处理静态私有嵌套类

1 个答案: