将对象的嵌套数组列表从适配器传递到活动答案

【问题标题】：Passing nested arraylist of object from adapter to activity将对象的嵌套数组列表从适配器传递到活动
【发布时间】：2018-10-23 01:42:03
【问题描述】：

我试图将嵌套对象的数组列表从适配器传递给活动，而该活动不是创建适配器的活动。我可以将整数或任何其他数据传递给它，但对象的数组列表为空。

public class Rate implements Parcelable{
public final static Parcelable.Creator<Rate> CREATOR = new Creator<Rate>() {
    @SuppressWarnings({
            "unchecked"
    })
    public Rate createFromParcel(Parcel in) {
        return new Rate(in);
    }

    public Rate[] newArray(int size) {
        return (new Rate[size]);
    }

};
@SerializedName("header")
@Expose
private String header;
@SerializedName("body")
@Expose
private List<Body> body = null;
@SerializedName("footer")
@Expose
private String footer;
@SerializedName("type")
@Expose
private String rateCardType;
@SerializedName("rules")
@Expose
private List<Rule> rateRules = null;

protected RateCard(Parcel in) {
    this.header = ((String) in.readValue((String.class.getClassLoader())));
    in.readList(this.body, (Body.class.getClassLoader()));
    this.footer = ((String) in.readValue((String.class.getClassLoader())));
    this.rateCardType = ((String) in.readValue((String.class.getClassLoader())));
    in.readList(this.rateCardRules, (Rule.class.getClassLoader()));
}

public Rate() {
}

public List<Rule> getRateCardRules() {
    return rateCardRules;
}

public void setRateCardRules(List<Rule> rateCardRules) {
    this.rateCardRules = rateCardRules;
}

public String getHeader() {
    return header;
}

public void setHeader(String header) {
    this.header = header;
}

public List<Body> getBody() {
    return body;
}

public void setBody(List<Body> body) {
    this.body = body;
}

public String getFooter() {
    return footer;
}

public void setFooter(String footer) {
    this.footer = footer;
}

public String getRateCardType() {
    return rateCardType;
}

public void setRateCardType(String rateCardType) {
    this.rateCardType = rateCardType;
}

public void writeToParcel(Parcel dest, int flags) {
    dest.writeValue(header);
    dest.writeList(body);
    dest.writeValue(footer);
    dest.writeValue(rateCardType);
    dest.writeList(rateCardRules);
}

public int describeContents() {
    return  0;
}

}

我想将规则对象数组列表传递给另一个活动。我的规则类如下图

public class Rule implements Parcelable{
public final static Parcelable.Creator<Rule> CREATOR = new Creator<Rule>() {

    @SuppressWarnings({
            "unchecked"
    })
    public Rule createFromParcel(Parcel in) {
        return new Rule(in);
    }

    public Rule[] newArray(int size) {
        return (new Rule[size]);
    }

};
@SerializedName("rule")
@Expose
private  DataRows ruleData;
@SerializedName("rule_conditions")
@Expose
private List<DataRows> ruleConditions;
@SerializedName("slots")
@Expose
private List<DataRows> slots;
@SerializedName("header")
@Expose
private DataRows header;

protected Rule(Parcel in) {
    in.readList(this.ruleConditions, (DataRows.class.getClassLoader()));
    in.readList(this.slots, (DataRows.class.getClassLoader()));
    this.ruleData = in.readParcelable((DataRows.class.getClassLoader()));
    this.header = in.readParcelable((DataRows.class.getClassLoader()));
}

public Rule() {
}

public DataRows getRuleData() {
    return ruleData;
}

public void setRuleData(DataRows ruleData) {
    this.ruleData = ruleData;
}

public List<DataRows> getRuleConditions() {
    return ruleConditions;
}

public void setRuleConditions(List<DataRows> ruleConditions) {
    this.ruleConditions = ruleConditions;
}

public List<DataRows> getSlots() {
    return slots;
}

public void setSlots(List<DataRows> slots) {
    this.slots = slots;
}

public DataRows getHeader() {
    return header;
}

public void setHeader(DataRows header) {
    this.header = header;
}
public void writeToParcel(Parcel dest, int flags) {
    dest.writeList(ruleConditions);
    dest.writeList(slots);
    dest.writeParcelable(ruleData, flags);
    dest.writeParcelable(header, flags);
}

public int describeContents() {
    return  0;
}

}

我的 DataRows 类

public class DataRows implements Parcelable{
public final static Parcelable.Creator<DataRows> CREATOR = new Creator<DataRows>() {


    @SuppressWarnings({
            "unchecked"
    })
    public DataRows createFromParcel(Parcel in) {
        return new DataRows(in);
    }

    public DataRows[] newArray(int size) {
        return (new DataRows[size]);
    }

};
@SerializedName("key")
@Expose
private String key;
@SerializedName("value")
@Expose
private String value;

public String getKey() {
    return key;
}

public void setKey(String key) {
    this.key = key;
}

public String getValue() {
    return value;
}

public void setValue(String value) {
    this.value = value;
}

protected DataRows(Parcel in) {
    this.key = ((String) in.readValue((String.class.getClassLoader())));
    this.value = ((String) in.readValue((String.class.getClassLoader())));
}

public DataRows() {
}

public void writeToParcel(Parcel dest, int flags) {
    dest.writeValue(key);
    dest.writeValue(value);
}

public int describeContents() {
    return  0;
}

}

这就是我试图传递价值的方式

Intent intent = new Intent(context, RulesDetailActivity.class);
        Bundle bundle = new Bundle();
        bundle.putParcelableArrayList("rules", (ArrayList<? extends Parcelable>) ruleList);
        bundle.putInt("current_rule_index", ruleIndex);
        startActivity(context, bundle, intent);

我的目标活动中的“规则”为空。这里出了什么问题。有人可以帮忙吗？

【问题讨论】：

标签： android android-intent parameter-passing parcelable

【解决方案1】：

对于这类问题，我总是喜欢使用 Gson 库。这是我的解决方案。

导入 gson 库。

compile 'com.google.code.gson:gson:2.7'

使用适配器类中的 gson 将嵌套的 Arraylist 转换为字符串。

Gson gson = new Gson();
Intent intent = new Intent(context, RulesDetailActivity.class);
intent.putExtra("rules", gson.toJson(ruleList);
startActivity(intent);

然后在 RulesDetailActivity 类中执行以下操作：

Gson gson = new Gson();
String gson = getIntent().getStringExtra("rules");
Type type = new TypeToken<List<Rule>>() {
            }.getType();
ArraList<Rule> rules = gson.fromGson(gson, type);

【讨论】：