我正在覆盖 onCreateDialog 和 onPrepareDialog 方法或 Dialog 类。
我按照 Reto Meier 的专业 Android 应用程序开发书第 5 章中的示例提取了一些 XML 数据,然后使用对话框显示信息。
我基本上完全遵循了它,但更改了变量以适合我自己的 XML 模式,如下所示:
@Override
public Dialog onCreateDialog(int id) {
switch(id) {
case (SETTINGS_DIALOG) :
LayoutInflater li = LayoutInflater.from(this);
View settingsDetailsView = li.inflate(R.layout.details, null);
AlertDialog.Builder settingsDialog = new AlertDialog.Builder(this);
settingsDialog.setTitle("Provisioned Settings");
settingsDialog.setView(settingsDetailsView);
return settingsDialog.create();
}
return null;
}
@Override
public void onPrepareDialog(int id, Dialog dialog) {
switch(id) {
case (SETTINGS_DIALOG) :
String afpunText = " ";
if(setting.getAddForPublicUserNames() == 1){
afpunText = "Yes";
}
else{
afpunText = "No";
}
String Text = "Login Settings: " + "\n"
+ "Password: " + setting.getPassword() + "\n"
+ "Server: " + setting.getServerAddress() + "\n";
AlertDialog settingsDialog = (AlertDialog)dialog;
settingsDialog.setTitle(setting.getUserName());
tv = (TextView)settingsDialog.findViewById(R.id.detailsTextView);
if (tv != null)
tv.setText(Text);
break;
}
}
在我尝试更改屏幕方向之前它工作正常,当我这样做时 onPrepareDialog 被调用,但我的所有变量都出现空指针异常。
即使我告诉我的活动忽略清单中的屏幕方向,错误仍然存在。
所以我认为书中的例子中遗漏了一些东西,我需要重写另一种方法来保存我的变量吗?
我现在添加了以下内容:
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
// Save UI state changes to the savedInstanceState.
// This bundle will be passed to onCreate if the process is
// killed and restarted.
savedInstanceState.putString("Username", setting.getUserName());
savedInstanceState.putString("Password", setting.getPassword());
savedInstanceState.putString("Server", setting.getServerAddress());
super.onSaveInstanceState(savedInstanceState);
}
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
settings.clear();
// Restore UI state from the savedInstanceState.
// This bundle has also been passed to onCreate.
username = savedInstanceState.getString("Username");
password = savedInstanceState.getString("Password");
serveraddress = savedInstanceState.getString("Server");
Settings setting = new Settings(username, password, serveraddress);
addNewSettings(setting);
}
但我仍然收到空指针异常