我遇到了一个问题，我想将 Set 从 DialogFragment 传递回最初调用它的 Fragment。
我尝试实现一个接口(interface)，但我似乎无法让它从 fragment 正常工作。
是否有另一种方式从 DialogFragment >> Fragment 获取参数？或者我是否需要在 Activity 上实现接口(interface)，然后将其从那里移动？
这个问题似乎是一个NullPointerException，我很确定这是因为该接口(interface)需要在 Activity 级别实现，而不是在 Fragment 级别实现。点击对话框的“肯定按钮”时会发生崩溃。
对话框 fragment
public class CustomPermissionDialog extends DialogFragment implements
OnCheckedChangeListener {
String _permission;
View convertView;
AlertDialog.Builder builder;
Switch alertDelete;
Set<String> permSet = new TreeSet<String>();
public static interface OnCompleteDialogInterface {
public abstract void OnCompleteDialog(Set mPermSet);
}
private OnCompleteDialogInterface mInterface;
public CustomPermissionDialog(Context context, String permissionName) {
_permission = permissionName;
mInterface = (OnCompleteDialogInterface) getActivity();
// TODO Auto-generated constructor stub
}
public Dialog onCreateDialog(Bundle savedInstanceState) {
LayoutInflater inflater = getActivity().getLayoutInflater();
builder = new AlertDialog.Builder(getActivity());
if (_permission == "Alerts") {
convertView = (View) inflater
.inflate(
getResources().getLayout(
R.layout.alerts_perm_dialog), null);
alertDelete = (Switch) convertView
.findViewById(R.id.switchAlertDelete);
alertDelete.setOnCheckedChangeListener(this);
}
if (_permission == "Automation") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.automation_perm_dialog),
null);
}
if (_permission == "Books") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.books_perm_dialog), null);
}
if (_permission == "Codes") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.codes_perm_dialog), null);
}
if (_permission == "DBS") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.dbs_perm_dialog), null);
}
if (_permission == "Feedback") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.feedback_perm_dialog),
null);
}
if (_permission == "Groups") {
convertView = (View) inflater
.inflate(
getResources().getLayout(
R.layout.groups_perm_dialog), null);
}
if (_permission == "Inventory") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.inventory_perm_dialog),
null);
}
if (_permission == "Jobs") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.jobs_perm_dialog), null);
}
if (_permission == "Locations") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.locations_perm_dialog),
null);
}
if (_permission == "Logs") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.logs_perm_dialog), null);
}
if (_permission == "Messages") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.messages_perm_dialog),
null);
}
if (_permission == "Services") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.services_perm_dialog),
null);
}
if (_permission == "Settings") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.settings_perm_dialog),
null);
}
if (_permission == "Templates") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.templates_perm_dialog),
null);
}
if (_permission == "Tools") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.tools_perm_dialog), null);
}
if (_permission == "Updates") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.updates_perm_dialog),
null);
}
if (_permission == "Users") {
convertView = (View) inflater.inflate(
getResources().getLayout(R.layout.users_perm_dialog), null);
}
// defining the alertdialog
builder.setTitle(_permission + " Permissions");
builder.setView(convertView);
builder.setPositiveButton(R.string.accept,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// do something with the new note
mInterface.OnCompleteDialog(permSet);
}
}).setNegativeButton(R.string.cancel,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// User cancelled the dialog
}
});
return builder.create();
}
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
// TODO Auto-generated method stub
if (alertDelete.isChecked()) {
// The toggle is enabled
permSet.add("alert_delete");
Log.e("ALERTDELETE", "CHECKED");
} else {
// The toggle is disabled
permSet.remove("alert_delete");
Log.e("ALERTDELETE", "UNCHECKED");
}
}
}
fragment 内部
@Override
public void OnCompleteDialog(Set mPermSet) {
// TODO Auto-generated method stub
this.permSet = mPermSet;
String tempPermString = permSet.toString();
Log.e("PERMISSIONS", tempPermString);
}
堆栈跟踪
10-30 11:41:30.081: E/AndroidRuntime(16925): FATAL EXCEPTION: main
10-30 11:41:30.081: E/AndroidRuntime(16925): Process: com.e.main, PID: 16925
10-30 11:41:30.081: E/AndroidRuntime(16925): java.lang.NullPointerException
10-30 11:41:30.081: E/AndroidRuntime(16925): at com.e.dialog.CustomPermissionDialog$1.onClick(CustomPermissionDialog.java:171)
10-30 11:41:30.081: E/AndroidRuntime(16925): at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
10-30 11:41:30.081: E/AndroidRuntime(16925): at android.os.Handler.dispatchMessage(Handler.java:102)
10-30 11:41:30.081: E/AndroidRuntime(16925): at android.os.Looper.loop(Looper.java:136)
10-30 11:41:30.081: E/AndroidRuntime(16925): at android.app.ActivityThread.main(ActivityThread.java:5105)
10-30 11:41:30.081: E/AndroidRuntime(16925): at java.lang.reflect.Method.invokeNative(Native Method)
10-30 11:41:30.081: E/AndroidRuntime(16925): at java.lang.reflect.Method.invoke(Method.java:515)
10-30 11:41:30.081: E/AndroidRuntime(16925): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792)
10-30 11:41:30.081: E/AndroidRuntime(16925): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608)
最佳答案
您的空指针是由于尝试使用 getActivity() 在 DialogFragment 的构造函数中设置 mInterface 造成的。此时 fragment 生命周期中的 getActivity() 为 null。
尝试在onCreate中设置它，或者在调用它时将 Activity 强制转换为接口(interface)(假设您的 Activity 保证实现您的接口(interface))
((OnCompleteDialogInterface) getActivity()).OnCompleteDialog(permSet);
另一个问题是您的字符串比较都是错误的。您应该使用
if (_permission.equals("whatever"))
其次，您应该使用 if/else 语句来检查您的 _permission 字符串，以避免不必要的检查。
此外， fragment 应该有空的构造函数。您应该了解如何使用 fragment 的 .setArgument(bundle) 方法传递 _permissions 字符串
你的布局膨胀有点过于复杂
而不是
convertView = (View) inflater.inflate(getResources().getLayout(R.layout.jobs_perm_dialog), null);
你可以直接使用
convertView = inflater.inflate(R.layout.jobs_perm_dialog, null);
关于java - 将参数从 DialogFragment 传递到 Fragment，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26657427/