我在app中为我的两个微调器处理onSavedInstance
和onRestoreInstance
时遇到问题。
我有两个SpinnerAdapter
,可以动态填充一对ArrayAdapter<String>
- adapter1 / adapter2和adapter3 / adapter4。
在onCreate方法app中为它们创建4个适配器,当用户按下button1
时,它将spinnerFrom
和spinnerTo
与adapter1和adapter2一起填充,当button2
分别用adapter3和adapter4填充微调器时。
据我了解生命周期 - 当屏幕旋转时,android会破坏应用程序,然后从头开始恢复它。
所以在onSavedInstance
i把我的旋转器捆绑起来
savedInstanceState.putInt("from",spinnerFrom.getSelectedItemPosition);
savedInstanceState.putInt("to",spinnertTo.getSelectedItemPosition());
在恢复时我从包中检索它们:
spinnerFrom.setSelection(savedInstanceState.getInt("from"));
spinnertTo.setSelection(savedInstanceState.getInt("to"));
问题是:当应用程序恢复时,它会丢失我的适配器并且它们会获得空值。
为了检查它,我创建了技术按钮和下一个代码:
protected void checkAdapter () {
//get Adapter from spinners
SpinnerAdapter valueAdapter = spinnerFrom.getAdapter();
SpinnerAdapter resultAdapter = spinnertTo.getAdapter();
if (valueAdapter == null | resultAdapter== null) {
Toast.makeText(this, “adapter null” , Toast.LENGTH_SHORT).show();
}
else{
Toast.makeText(this, “adapters not null” , Toast.LENGTH_SHORT).show();
}
}
问题:如何正确地将AdroidSpinner及其适配器放入OnSavedInstance包中,然后将其恢复到onRestoreInstance,以防它在onCreate中填充但不在onClick方法中?提前致谢!
App java代码:
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.TextView;
import android.widget.Toast;
import butterknife.BindView;
import butterknife.ButterKnife;
import butterknife.OnClick;
public class MainActivity extends AppCompatActivity {
protected double getEnteredValue;
protected SpinnerAdapter checkAdapter;
protected int pos;
protected ArrayAdapter<String> adapter 1, adapter2, adapter3,
adapter4;
//butterknife bindings
@BindView(R.id.unit_From_spinner)Spinner spinnerFrom;
@BindView(R.id.unit_To_spinner)Spinner spinnertTo;
@BindView(R.id.radio_result_group) RadioGroup resultGroup;
@BindView(R.id.radio_value_gropu) RadioGroup valueGroup;
@BindView(R.id.valueEditTextView) EditText valueEdit;
@BindView(R.id.resultView) TextView resultView;
@BindView(R.id.conver_button) Button convertButton;
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
savedInstanceState.putString("result",resultView.getText().toString()); savedInstanceState.putString("value",valueEdit.getText().toString()); savedInstanceState.putInt("from",spinnerFrom.getSelectedItemPosition);
savedInstanceState.putInt("to",spinnertTo.getSelectedItemPosition());
savedInstanceState.putInt("radGroup1",resultGroup.getCheckedRadioButtonId());
savedInstanceState.putInt("radGroup2", valueGroup.getCheckedRadioButtonId());
super.onSaveInstanceState(savedInstanceState);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.unifiedlayout);
ButterKnife.bind(this);
//adapters for spinners
adapter1 = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_spinner_item,getResources().getStringArray( R.array.adapter_1) );
adapter2 = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_spinner_item,getResources().getStringArray(R.array. adapter_2));
adapter3 = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_spinner_item,getResources().getStringArray( R.array. adapter_3) );
adapter4 = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_spinner_item,getResources().getStringArray(R.array. adapter_4));}
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
resultView.setText(savedInstanceState.getString("result"));
valueEdit.setText(savedInstanceState.getString("value"));
spinnerFrom.setSelection(savedInstanceState.getInt("from"));
spinnertTo.setSelection(savedInstanceState.getInt("to"));
super.onSaveInstanceState(savedInstanceState);
}
//OnClick
@OnClick({R.id.button1, R.id.button2,R.id.button3,R.id.button4} )
public void setViewOnClickEvent(View view){
switch(view.getId()){
case R.id. button1:
fillSpinner(adapter1, adapter2); // fill spinner with values
break;
case R.id. button2:
fillSpinner(adapter3,
adapter4);
break;
//button for check if any adapter active
case R.id.buttonAdapter:
checkAdapter () ;
break;
}
}
//fill spinners when user checks radiobutton in radiogroups
protected void fillSpinner (final ArrayAdapter<String> spinnerToAdapter,
final ArrayAdapter<String> spinnerFromAdapter){
valueGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup valueGroup, int checkedId) {
pos = valueGroup.indexOfChild(findViewById(checkedId));
switch (pos) {
case 0:
spinnerFrom.setAdapter(spinnerToAdapter);
break;
case 1:
spinnerFrom.setAdapter(spinnerFromAdapter);
break;
}
}
});
resultGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup resultGroup, int checkedId) {
pos = resultGroup.indexOfChild(findViewById(checkedId));
switch (pos) {
case 0:
spinnertTo.setAdapter(spinnerToAdapter);
break;
case 1:
spinnertTo.setAdapter(spinnerFromAdapter);
break;
}
}
});
}
//simple method for check if both spinners has null value
protected void checkAdapter () {
//get Adapter from spinners
SpinnerAdapter valueAdapter = spinnerFrom.getAdapter();
SpinnerAdapter resultAdapter = spinnertTo.getAdapter();
if (valueAdapter == null | resultAdapter== null) {
Toast.makeText(this, “adapter null” , Toast.LENGTH_SHORT).show();
}
else{
Toast.makeText(this, “adapters not null” , Toast.LENGTH_SHORT).show();
}
}
编辑:答案是不完美的它不起作用我想要的,但这种方式让我有可能保存适配器:1.Create方法从适配器检索字符串数组,想要'保存:
public static String[] getStringArray(SpinnerAdapter adapter) {
String[] a = new String[adapter.getCount()];
for (int i = 0; i < a.length; i++)
a[i] = adapter.getItem(i).toString();
return a;
}
2.在onSavedInstanceState中输入下一个代码:
// here i saving arraylist that ussualy i get from resources.
savedInstanceState.putStringArray(ADAPTER_TO,getStringArray(spinnerFrom.getAdapter()));
savedInstanceState.putStringArray(ADAPTER_FROM,getStringArray(spinnerFrom.getAdapter()));
3.在restoreInstance中创建新的适配器,它将使用值填充您的微调器,并使用savedInstanceState.getStringArray(ADAPTER_TO)填充保存的值:
toAdapter = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_spinner_item, savedInstanceState.getStringArray(ADAPTER_TO));
fromAdapter = new ArrayAdapter<>(getApplicationContext(), android.R.layout.simple_spinner_item, savedInstanceState.getStringArray(ADAPTER_FROM));
//use spinner.setAdapter to set created adapter.
spinnerFrom.setAdapter (fromAdapter)
spinnerTo.setAdapter (toAdapter)
这仍然无法正常工作,但如果您想在旋转屏幕上保存微调器状态,您可以尝试使用此逻辑。
您可以使用两种方法实现此目的。 1)(推荐)使用ViewModels(架构组件)2)使用保存和恢复状态。
1)。您可以创建viewModel,每当用户选择某些内容时,请使用指定的值调用ViewModel。通过观察ViewModel,您可以获得该值的最新更改(即使在轮换更改后),因为ViewModel将保持活动状态。
3)将用户的选择保存在活动内的局部变量中,然后在保存和恢复中,put
和get
的值如下:
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
savedInstanceState.putInt("firstSpinnerPosition", variableThatHasTheChangedPosition);
savedInstanceState.putInt("secondSpinnerPosition", variableThatHasTheChangedPositionForSecond);
// other stuff.
}
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
variableThatHasTheChangedPosition = savedInstanceState.getInt("firstSpinnerPosition");
variableThatHasTheChangedPositionForSecond = savedInstanceState.getInt("secondSpinnerPosition");
//notify your adapter of the changes
}
斯宾纳有onNothingSelected()
方法。
在那种方法中,尝试使用spinneradapter.getLastVisiblePosition()
。
当您离开应用程序时,保存最后一个位置,当您回来时,请使用最后一个位置。
希望能帮助到你。