我有一个抽象类 Drill 和 4 个扩展它的类（addClass、divClass 等）。Drill 类实现了 parcelable。现在我有 GamePlayActivity 需要将 Array of Drills 传递给 Result 活动，我有两个编译问题。以下是相关代码：
钻头类：
...
public Drill(Parcel in) {
readFromParcel(in);
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
// We just need to write each field into the
// parcel. When we read from parcel, they
// will come back in the same order
dest.writeInt(firstNumber);
dest.writeInt(secondNumber);
dest.writeInt(answer);
dest.writeInt(userAnswer);
dest.writeString(userAnswerString);
dest.writeString(symbol);
dest.writeInt(minBound);
dest.writeInt(maxBound);
dest.writeInt(drillNumber);
}
/**
*
* Called from the constructor to create this
* object from a parcel.
*
* @param in parcel from which to re-create object
*/
protected void readFromParcel(Parcel in) {
// We just need to read back each
// field in the order that it was
// written to the parcel
firstNumber = in.readInt();
secondNumber = in.readInt();
answer = in.readInt();
userAnswer = in.readInt();
userAnswerString = in.readString();
symbol = in.readString();
minBound = in.readInt();
maxBound = in.readInt();
}
public static final Parcelable.Creator<Drill> CREATOR = new Parcelable.Creator<Drill>() {
public Drill createFromParcel(Parcel in) {
return new Drill(in); // compilation error
}
public Drill[] newArray(int size) {
return new Drill[size];
}
};
}
我认为这里的错误是因为 Drill 调用是抽象的。
这是 addDrill 类，其他类看起来相同：
package com.simplemathgame;
import android.os.Parcel;
import android.os.Parcelable;
public class AddDrill extends Drill {
AddDrill(int min, int max) {
super(min, max);
symbol = "+";
firstNumber = getRandomNumber(min, max);
secondNumber = getRandomNumber(min, max);
answer = answerCalculatetion();
}
private AddDrill(Parcel in) {
super(in);
}
public void readFromParcel(Parcel in) {
super.readFromParcel(in);
}
@Override
public void writeToParcel(Parcel out, int flags) {
super.writeToParcel(out, flags);
}
@Override
public int describeContents() {
return 0;
}
protected int answerCalculatetion() {
return (this.getFirstNumber() + this.getSecondNumber());
}
}
这是传递数组的类 GamePlayClass：
package com.simplemathgame;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class GamePlayActivity extends Activity {
...
Drill[] arrayOfDrills;
int dIndex = 0;
...
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_play);
...
arrayOfDrills = new Drill[addDrills + subDrills + mulDrills + divDrills];
...
finishButton.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View arg0) {
...
Intent resultsActivity = new Intent(GamePlayActivity.this, Results.class);
resultsActivity.putExtra("drillArray", arrayOfDrills);
startActivity(resultsActivity);
}
});
}
public static <T> void shuffle(T[] array) {
for (int i = array.length; i > 1; i--) {
T temp = array[i - 1];
int randIx = (int) (Math.random() * i);
array[i - 1] = array[randIx];
array[randIx] = temp;
}
}
}
最后一部分是接收数组的 Result 活动：
package com.simplemathgame;
import android.os.Bundle;
import android.app.Activity;
public class Results extends Activity {
Drill[] arrayOfDrills;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_results);
Bundle extras = getIntent().getExtras();
arrayOfDrills = extras.getParcelable("drillArray"); // compilation error
}
}
在这里我不知道为什么会发生错误。
第一个编译错误：无法实例化类型 Drill
第二个编译错误：类型不匹配：无法从 Drill[]&Parcelable 转换为 Drill[]
我应该如何修复我的代码？谢谢！