java - 如何在 Activity 之间发送自定义对象数组？

Question

我发现他们发送 ArrayList 的很多地方，但我需要能够将我的自定义对象“Card”的简单数组从 Activity A 发送到 B。我相信我已经以允许的方式创建了类我的对象将作为 Intent 的额外内容传递。这是我的 Parcelable 类卡片:

import android.os.Parcel;
import android.os.Parcelable;

public class Card implements Parcelable{
   public String suit;
   public int value;
   public String color;

public Card(String suit, int value){
    this.suit = suit;
    this.value = value;

    if(suit == "hearts" || suit == "diamonds"){
        this.color = "red";
    }else{
        this.color = "black";
    }
}

public String toString(){
    String s = suit;
    return s;
}

 private Card(Parcel in) {
     value = in.readInt();
     color = in.readString();
     suit = in.readString();
    }

public int describeContents() {
    return 0;
}

public void writeToParcel(Parcel out, int flags) {
    out.writeInt(value);
    out.writeString(color);
    out.writeString(suit);
}

public static final Parcelable.Creator<Card> CREATOR
        = new Parcelable.Creator<Card>() {
    public Card createFromParcel(Parcel in) {
        return new Card(in);
    }

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

这就是我将其添加到 Activity A(即主要 Activity )的 Intent 中的方式:

    Card[] myCardArray = new Card[7];
    //Note the card array is filled before starting the intent.
    Intent intnt = new Intent(this, B.class);
    intnt.putExtra("array", myCardArray);
    startActivity(intnt);

然后我在 Activity B 的 onCreate 方法中检索它:

    allCards = (Card[]) getIntent().getExtras().getParcelableArray("array");

unfourntunatley 应用程序在到达 Activity B 中的代码后立即崩溃。我是否以错误的方式调用它？这是日志

09-05 15:27:37.007: E/Trace(26971): error opening trace file: No such file or directory (2)
09-05 15:27:37.007: D/ActivityThread(26971): setTargetHeapUtilization:0.25
09-05 15:27:37.007: D/ActivityThread(26971): setTargetHeapIdealFree:8388608
09-05 15:27:37.007: D/ActivityThread(26971): setTargetHeapConcurrentStart:2097152
09-05 15:27:37.228: D/libEGL(26971): loaded /system/lib/egl/libEGL_adreno200.so
09-05 15:27:37.228: D/libEGL(26971): loaded /system/lib/egl/libGLESv1_CM_adreno200.so
09-05 15:27:37.228: D/libEGL(26971): loaded /system/lib/egl/libGLESv2_adreno200.so
09-05 15:27:37.248: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:37.268: E/(26971): <s3dReadConfigFile:75>: Can't open file for reading
09-05 15:27:37.268: E/(26971): <s3dReadConfigFile:75>: Can't open file for reading
09-05 15:27:37.268: D/OpenGLRenderer(26971): Enabling debug mode 0
09-05 15:27:39.640: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:41.963: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:42.844: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:44.425: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:46.257: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:47.799: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:49.781: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:51.182: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:51.943: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:55.237: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:56.468: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:57.910: I/Adreno200-EGLSUB(26971): <ConfigWindowMatch:2087>: Format RGBA_8888.
09-05 15:27:59.101: D/AndroidRuntime(26971): Shutting down VM
09-05 15:27:59.101: W/dalvikvm(26971): threadid=1: thread exiting with uncaught exception (group=0x412e8438)
09-05 15:27:59.111: E/AndroidRuntime(26971): FATAL EXCEPTION: main
09-05 15:27:59.111: E/AndroidRuntime(26971): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.marco.pokerhands2/com.marco.pokerhands2.DisplayHands}: java.lang.ClassCastException: android.os.Parcelable[] cannot be cast to com.marco.pokerhands2.Card[]
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2088)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2113)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.app.ActivityThread.access$700(ActivityThread.java:139)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1224)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.os.Handler.dispatchMessage(Handler.java:99)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.os.Looper.loop(Looper.java:137)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.app.ActivityThread.main(ActivityThread.java:4918)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at java.lang.reflect.Method.invokeNative(Native Method)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at java.lang.reflect.Method.invoke(Method.java:511)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1004)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:771)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at dalvik.system.NativeStart.main(Native Method)
09-05 15:27:59.111: E/AndroidRuntime(26971): Caused by: java.lang.ClassCastException: android.os.Parcelable[] cannot be cast to com.marco.pokerhands2.Card[]
09-05 15:27:59.111: E/AndroidRuntime(26971):    at com.marco.pokerhands2.DisplayHands.onCreate(DisplayHands.java:30)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.app.Activity.performCreate(Activity.java:5048)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
09-05 15:27:59.111: E/AndroidRuntime(26971):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2052)
09-05 15:27:59.111: E/AndroidRuntime(26971):    ... 11 more

Answer 1

你不能像那样转换数组。如果你有一个 Parcelable 数组，并且你想将它转换为一个 Card 数组，你需要遍历数组并分别转换每个对象:

Parcelable[] allParcelables = getIntent().getExtras().getParcelableArray("array");
Card[] allCards = new Card[allParcelables.length];
for (int i = 0 ; i < allParcelables.length; i++) {
    allCards[i] = (Card)allParcelables[i];
}