如何将 ArrayList 中的类从一个活动传递到另一个活动 [英] How to pass Class of Class in ArrayList from one Activity to Another Activity

问题描述

我想将 ArrayList 的一个对象传递给 Next Activity.

I want to pass one object of ArrayList<Links> to Next Activity.

我已经检查了 Parcelable 来实现这一点，但我在 Links 类中有另一个 Class 对象 Stream 类.

I have checked use of Parcelable to achieve this but I have one another Class object of Stream class in Links class.

如何将这个 Links 对象传递给下一个活动

How can i pass this Links object to Next Activity

public class Links implements Parcelable {

    private String name;
    private Streams streams;

    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @param streams the streams to set
     */
    public void setStreams(Streams streams) {
        this.streams = streams;
    }

    /**
     * @return the streams
     */
    public Streams getStreams() {
        return streams;
    }

    @Override
    public int describeContents() {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        // TODO Auto-generated method stub
        /**
         ** WHAT CAN I DO HERE...???
         **/
    }
}

Stream 类:

public class Streams {
    private String link;
    private String stream;

    /**
     * @param link the link to set
     */
    public void setLink(String link) {
        this.link = link;
    }
    /**
     * @return the link
     */
    public String getLink() {
        return link;
    }
    /**
     * @param stream the stream to set
     */
    public void setStream(String stream) {
        this.stream = stream;
    }
    /**
     * @return the stream
     */
    public String getStream() {
        return stream;
    }
}

我想将 ArrayList 对象发送到下一个活动.我怎样才能?

I want to send ArrayList object to next activity. how can i?

我在 Logcat:

06-19 16:23:00.820: E/AndroidRuntime(21080): FATAL EXCEPTION: main
06-19 16:23:00.820: E/AndroidRuntime(21080): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gtu.gtupapers/com.gtu.gtupapers.StreamSelection}: java.lang.NullPointerException: expected receiver of type com.gtu.gtupapers.Links, but got null
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2129)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2154)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.app.ActivityThread.access$700(ActivityThread.java:146)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1260)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Looper.loop(Looper.java:137)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.app.ActivityThread.main(ActivityThread.java:4949)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at java.lang.reflect.Method.invokeNative(Native Method)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at java.lang.reflect.Method.invoke(Method.java:511)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1043)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:810)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at dalvik.system.NativeStart.main(Native Method)
06-19 16:23:00.820: E/AndroidRuntime(21080): Caused by: java.lang.NullPointerException: expected receiver of type com.gtu.gtupapers.Links, but got null
06-19 16:23:00.820: E/AndroidRuntime(21080):    at java.lang.reflect.Field.getField(Native Method)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at java.lang.reflect.Field.get(Field.java:269)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Parcel.readParcelable(Parcel.java:2066)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Parcel.readValue(Parcel.java:1965)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Parcel.readListInternal(Parcel.java:2235)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Parcel.readArrayList(Parcel.java:1655)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Parcel.readValue(Parcel.java:1986)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Parcel.readMapInternal(Parcel.java:2226)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Bundle.unparcel(Bundle.java:223)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.os.Bundle.getParcelableArrayList(Bundle.java:1209)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.content.Intent.getParcelableArrayListExtra(Intent.java:4477)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at com.gtu.gtupapers.StreamSelection.onCreate(StreamSelection.java:16)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.app.Activity.performCreate(Activity.java:5185)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
06-19 16:23:00.820: E/AndroidRuntime(21080):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2093)
06-19 16:23:00.820: E/AndroidRuntime(21080):    ... 11 more

您的帮助将不胜感激...

Your help would be appreciated...

推荐答案

Links class:

public class Links implements Parcelable {

    private String name;
    private Streams streams;

    public Links(String name, Streams streams) {
        this.name = name;
        this.streams = streams;
    }

    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * @param streams the streams to set
     */
    public void setStreams(Streams streams) {
        this.streams = streams;
    }

    /**
     * @return the streams
     */
    public Streams getStreams() {
        return streams;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(name);
        dest.writeParcelable(streams, flags);
    }

    public static Parcelable.Creator<Links> CREATOR = new Parcelable.Creator<Links>() {

        @Override
        public Links createFromParcel(Parcel source) {
            String name = source.readString();
            Streams streams = source.readParcelable(Streams.class.getClassLoader());
            return new Links(name, streams);
        }

        @Override
        public Links[] newArray(int size) {
            return new Links[size];
        }
    };
}

Streams 类:

public class Streams implements Parcelable {
    private String link;
    private String stream;

    public Streams(String link, String stream) {
        this.link = link;
        this.stream = stream;
    }
    /**
     * @param link the link to set
     */
    public void setLink(String link) {
        this.link = link;
    }
    /**
     * @return the link
     */
    public String getLink() {
        return link;
    }
    /**
     * @param stream the stream to set
     */
    public void setStream(String stream) {
        this.stream = stream;
    }
    /**
     * @return the stream
     */
    public String getStream() {
        return stream;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(link);
        dest.writeString(stream);
    }

    public static final Parcelable.Creator<Streams> CREATOR = new Parcelable.Creator<Streams>() {

        @Override
        public Streams createFromParcel(Parcel source) {
            String link = source.readString();
            String stream = source.readString();
            return new Streams(link, stream);
        }

        @Override
        public Streams[] newArray(int size) {
            return new Streams[size];
        }
    };

}

然后就可以传递列表了:

Then you can pass the list:

Intent intent = new Intent(this, OtherActivity.class);
intent.putParcelableArrayListExtra("links", yourList);
startActivity(intent);

在OtherActivity中:

Intent intent = getIntent();
ArrayList<Links> links = intent.getParcelableArrayListExtra("links");

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