如何将 Enum 对象添加到 Android Bundle?
13 回答
枚举是可序列化的,所以没有问题。
给定以下枚举:
enum YourEnum {
TYPE1,
TYPE2
}
捆:
// put
bundle.putSerializable("key", YourEnum.TYPE1);
// get
YourEnum yourenum = (YourEnum) bundle.get("key");
意图:
// put
intent.putExtra("key", yourEnum);
// get
yourEnum = (YourEnum) intent.getSerializableExtra("key");
我知道这是一个老问题,但我遇到了同样的问题,我想分享我是如何解决它的。关键是 Miguel 所说的:枚举是可序列化的。
给定以下枚举:
enum YourEnumType {
ENUM_KEY_1,
ENUM_KEY_2
}
放:
Bundle args = new Bundle();
args.putSerializable("arg", YourEnumType.ENUM_KEY_1);
为了完整起见,这是一个完整的示例,说明如何从包中放入和取回枚举。
给定以下枚举:
enum EnumType{
ENUM_VALUE_1,
ENUM_VALUE_2
}
您可以将枚举放入一个包中:
bundle.putSerializable("enum_key", EnumType.ENUM_VALUE_1);
并取回枚举:
EnumType enumType = (EnumType)bundle.getSerializable("enum_key");
我使用科特林。
companion object {
enum class Mode {
MODE_REFERENCE,
MODE_DOWNLOAD
}
}
然后放入Intent:
intent.putExtra(KEY_MODE, Mode.MODE_DOWNLOAD.name)
当您净获得价值时:
mode = Mode.valueOf(intent.getStringExtra(KEY_MODE))
It may be better to pass it as string from myEnumValue.name() and restore it from YourEnums.valueOf(s), as otherwise the enum's ordering must be preserved!
Longer explanation: Convert from enum ordinal to enum type
另外的选择:
public enum DataType implements Parcleable {
SIMPLE, COMPLEX;
public static final Parcelable.Creator<DataType> CREATOR = new Creator<DataType>() {
@Override
public DataType[] newArray(int size) {
return new DataType[size];
}
@Override
public DataType createFromParcel(Parcel source) {
return DataType.values()[source.readInt()];
}
};
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
dest.writeInt(this.ordinal());
}
}
在科特林:
enum class MyEnum {
NAME, SURNAME, GENDER
}
将此枚举放入捆绑包中:
Bundle().apply {
putInt(MY_ENUM_KEY, MyEnum.ordinal)
}
从 Bundle 中获取枚举:
val ordinal = getInt(MY_ENUM_KEY, 0)
MyEnum.values()[ordinal]
完整示例:
class MyFragment : Fragment() {
enum class MyEnum {
NAME, SURNAME, GENDER
}
companion object {
private const val MY_ENUM_KEY = "my_enum_key"
fun newInstance(myEnum: MyEnum) = MyFragment().apply {
arguments = Bundle().apply {
putInt(MY_ENUM_KEY, myEnum.ordinal)
}
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
with(requireArguments()) {
val ordinal = getInt(MY_ENUM_KEY, 0)
val myEnum = MyEnum.values()[ordinal]
}
}
}
在 Java 中:
public final class MyFragment extends Fragment {
private static final String MY_ENUM_KEY = "my_enum";
public enum MyEnum {
NAME,
SURNAME,
GENDER
}
public final MyFragment newInstance(MyEnum myEnum) {
Bundle bundle = new Bundle();
bundle.putInt(MY_ENUM_KEY, myEnum.ordinal());
MyFragment fragment = new MyFragment();
fragment.setArguments(bundle);
return fragment;
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle arguments = this.requireArguments();
int ordinal = arguments.getInt(MY_ENUM_KEY, 0);
MyEnum myEnum = MyEnum.values()[ordinal];
}
}
使用 bundle.putSerializable(String key, Serializable s) 和 bundle.getSerializable(String key):
enum Mode = {
BASIC, ADVANCED
}
Mode m = Mode.BASIC;
bundle.putSerializable("mode", m);
...
Mode m;
m = bundle.getSerializable("mode");
文档:http: //developer.android.com/reference/android/os/Bundle.html
我创建了一个 Koltin 扩展:
fun Bundle.putEnum(key: String, enum: Enum<*>) {
this.putString( key , enum.name )
}
inline fun <reified T: Enum<T>> Intent.getEnumExtra(key:String) : T {
return enumValueOf( getStringExtra(key) )
}
创建一个包并添加:
Bundle().also {
it.putEnum( "KEY" , ENUM_CLAS.ITEM )
}
并得到:
intent?.getEnumExtra< ENUM_CLAS >( "KEY" )?.let{}
对于Intent,您可以使用这种方式:
意图:科特林
第一活动:
val intent = Intent(context, SecondActivity::class.java)
intent.putExtra("type", typeEnum.A)
startActivity(intent)
第二活动:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
//...
val type = (intent.extras?.get("type") as? typeEnum.Type?)
}
需要注意的一件事 - 如果您使用bundle.putSerializable
aBundle
添加到通知中,您可能会遇到以下问题:
*** Uncaught remote exception! (Exceptions are not yet supported across processes.)
java.lang.RuntimeException: Parcelable encountered ClassNotFoundException reading a Serializable object.
...
要解决此问题,您可以执行以下操作:
public enum MyEnum {
TYPE_0(0),
TYPE_1(1),
TYPE_2(2);
private final int code;
private MyEnum(int code) {
this.code = navigationOptionLabelResId;
}
public int getCode() {
return code;
}
public static MyEnum fromCode(int code) {
switch(code) {
case 0:
return TYPE_0;
case 1:
return TYPE_1;
case 2:
return TYPE_2;
default:
throw new RuntimeException(
"Illegal TYPE_0: " + code);
}
}
}
然后可以像这样使用它:
// Put
Bundle bundle = new Bundle();
bundle.putInt("key", MyEnum.TYPE_0.getCode());
// Get
MyEnum myEnum = MyEnum.fromCode(bundle.getInt("key"));
我认为将 enum 转换为 int (对于普通枚举)然后在 bundle 上设置是最简单的方法。像这样的意图代码:
myIntent.PutExtra("Side", (int)PageType.Fornt);
然后检查状态:
int type = Intent.GetIntExtra("Side",-1);
if(type == (int)PageType.Fornt)
{
//To Do
}
但不适用于所有枚举类型!
一种简单的方法,将整数值分配给枚举
请参见以下示例:
public enum MyEnum {
TYPE_ONE(1), TYPE_TWO(2), TYPE_THREE(3);
private int value;
MyEnum(int value) {
this.value = value;
}
public int getValue() {
return value;
}
}
发送方:
Intent nextIntent = new Intent(CurrentActivity.this, NextActivity.class);
nextIntent.putExtra("key_type", MyEnum.TYPE_ONE.getValue());
startActivity(nextIntent);
接收方:
Bundle mExtras = getIntent().getExtras();
int mType = 0;
if (mExtras != null) {
mType = mExtras.getInt("key_type", 0);
}
/* OR
Intent mIntent = getIntent();
int mType = mIntent.getIntExtra("key_type", 0);
*/
if(mType == MyEnum.TYPE_ONE.getValue())
Toast.makeText(NextActivity.this, "TypeOne", Toast.LENGTH_SHORT).show();
else if(mType == MyEnum.TYPE_TWO.getValue())
Toast.makeText(NextActivity.this, "TypeTwo", Toast.LENGTH_SHORT).show();
else if(mType == MyEnum.TYPE_THREE.getValue())
Toast.makeText(NextActivity.this, "TypeThree", Toast.LENGTH_SHORT).show();
else
Toast.makeText(NextActivity.this, "Wrong Key", Toast.LENGTH_SHORT).show();