JSON implementation of SharedPreferences

Preferences.java

public class Preferences implements SharedPreferences {

    File file;
    JSONObject json;
    Set<OnSharedPreferenceChangeListener> listeners = new HashSet<>();

    public Preferences(File file) {
        this.file = file;
        json = loadJson();
    }

    JSONObject loadJson() {
        try {
            InputStream is = new FileInputStream(file);
            int size = is.available();
            byte[] buffer = new byte[size];
            is.read(buffer);
            is.close();

            return new JSONObject(new String(buffer, "UTF-8"));
        } catch (Exception e) {
        }
        return new JSONObject();
    }

    boolean saveJson() {
        if (json == null) {
            file.delete();
            return true;
        } else {
            OutputStreamWriter writer = null;
            try {
                writer = new OutputStreamWriter(new FileOutputStream(file));
                writer.write(json.toString());
                return true;
            } catch (Exception e) {
            } finally {
                try {
                    writer.close();
                } catch (Exception e) {
                }
            }
        }
        return false;
    }

    void set(JSONObject json) {
        this.json = json;
    }

    public static Map<String, Object> jsonToMap(JSONObject json) throws JSONException {
        Map<String, Object> retMap = new HashMap<String, Object>();

        if(json != JSONObject.NULL) {
            retMap = toMap(json);
        }
        return retMap;
    }

    public static Map<String, Object> toMap(JSONObject object) throws JSONException {
        Map<String, Object> map = new HashMap<>();

        Iterator<String> keysItr = object.keys();
        while(keysItr.hasNext()) {
            String key = keysItr.next();
            Object value = object.get(key);

            if(value instanceof JSONArray) {
                value = toList((JSONArray) value);
            }

            else if(value instanceof JSONObject) {
                value = toMap((JSONObject) value);
            }
            map.put(key, value);
        }
        return map;
    }

    public static List<Object> toList(JSONArray array) throws JSONException {
        List<Object> list = new ArrayList<Object>();
        for(int i = 0; i < array.length(); i++) {
            Object value = array.get(i);
            if(value instanceof JSONArray) {
                value = toList((JSONArray) value);
            }

            else if(value instanceof JSONObject) {
                value = toMap((JSONObject) value);
            }
            list.add(value);
        }
        return list;
    }

    @Override
    public Map<String, ?> getAll() {
        try {
            return toMap(json);
        } catch (Exception e) {
        }
        return new HashMap<>();
    }

    @Nullable
    @Override
    public String getString(String s, @Nullable String s1) {
        try {
            return json.getString(s);
        } catch (Exception e) {
            return s1;
        }
    }

    @Nullable
    @Override
    public Set<String> getStringSet(String s, @Nullable Set<String> set) {
        try {
            JSONArray ary = json.getJSONArray(s);
            if (ary != null) {
                Set<String> result = new HashSet<>();
                for (int i = 0; i < ary.length(); i++) {
                    result.add(ary.getString(i));
                }
                return result;
            }
        } catch (Exception e) {
        }
        return set;
    }

    @Override
    public int getInt(String s, int i) {
        try {
            return json.getInt(s);
        } catch (Exception e) {
            return i;
        }
    }

    @Override
    public long getLong(String s, long l) {
        try {
            return json.getLong(s);
        } catch (Exception e) {
            return l;
        }
    }

    @Override
    public float getFloat(String s, float v) {
        try {
            return (float) json.getDouble(s);
        } catch (Exception e) {
            return v;
        }
    }

    @Override
    public boolean getBoolean(String s, boolean b) {
        try {
            return json.getBoolean(s);
        } catch (Exception e) {
            return b;
        }
    }

    @Override
    public boolean contains(String s) {
        return json.has(s);
    }

    @Override
    public Editor edit() {
        return new Editor(json);
    }

    @Override
    public void registerOnSharedPreferenceChangeListener(OnSharedPreferenceChangeListener onSharedPreferenceChangeListener) {
        listeners.add(onSharedPreferenceChangeListener);
    }

    @Override
    public void unregisterOnSharedPreferenceChangeListener(OnSharedPreferenceChangeListener onSharedPreferenceChangeListener) {
        listeners.remove(onSharedPreferenceChangeListener);
    }

    public class Editor implements SharedPreferences.Editor {

        JSONObject json;

        public Editor(JSONObject json) {
            this.json = json;
        }

        @Override
        public SharedPreferences.Editor putString(String s, @Nullable String s1) {
            if (s1 != null) {
                try {
                    json.put(s, s1);
                } catch (Exception e) {
                }
            } else {
                remove(s);
            }
            return this;
        }

        @Override
        public SharedPreferences.Editor putStringSet(String s, @Nullable Set<String> set) {
            if (set != null) {
                try {
                    JSONArray array = new JSONArray();
                    for (String str: set) {
                        array.put(str);
                    }
                    json.put(s, array);
                } catch (Exception e) {
                }
            } else {
                remove(s);
            }
            return null;
        }

        @Override
        public SharedPreferences.Editor putInt(String s, int i) {
            try {
                json.put(s, i);
            } catch (Exception e) {
            }
            return this;
        }

        @Override
        public SharedPreferences.Editor putLong(String s, long l) {
            try {
                json.put(s, l);
            } catch (Exception e) {
            }
            return this;
        }

        @Override
        public SharedPreferences.Editor putFloat(String s, float v) {
            try {
                json.put(s, (double) v);
            } catch (Exception e) {
            }
            return this;
        }

        @Override
        public SharedPreferences.Editor putBoolean(String s, boolean b) {
            try {
                json.put(s, b);
            } catch (Exception e) {
            }
            return this;
        }

        @Override
        public SharedPreferences.Editor remove(String s) {
            json.remove(s);
            return this;
        }

        @Override
        public SharedPreferences.Editor clear() {
            json = new JSONObject();
            return this;
        }

        @Override
        public boolean commit() {
            apply();
            return saveJson();
        }

        @Override
        public void apply() {
            set(json);
        }
    }
}