从不同活动返回后数据丢失 onresume
Data Lost onresume after returning back from different activities
我是 android 编程的新手,我想我遇到了一个非常基本的问题。实际上在 Whosebug 上搜索了两天,但我无法找到适合我情况的解决方案。
所以总而言之,我尝试申请一个计算。
我有 5 个活动:MainActivity、ActivityA(selecting 一些东西并从 ArrayList 中获取价值),ActivityB(再次 selecting 一些东西并获取来自 ArrayList 的值),ActivityC(输入值并取另一个值),Activity D(输入值并取另一个值)
然后在 Mainactivity 上,这些值将用于方程式。
我通过使用意图获取值,并在 onresume 中对意图进行编码。
首先,我转到 ActivityA 和 select 我想要的,然后 return 回到 Mainactivity 并且我有所需的值,但是当我为 ActivityB 和 return 回到 Mainactivity,我丢失了 ActivityA 的值,因为我认为程序也会为 ActivityA 再次执行意图(这对所有其他活动都是一样的)。所以我认为我需要以某种方式将所有活动的意图分开。我尝试使用 sharedpreferences 或在所有具有不同值的活动上创建相同的字符串,以便在 onresume 部分的 if 或 switch 案例中使用,不幸的是我没有成功。
public class MainActivity extends AppCompatActivity {
//Değerlerin girildiği text kutucuklarının tanımlanması
EditText designPressure;
EditText corrosionAllowance;
EditText pipeDiameter;
EditText selectedMaterial;
EditText selectedAllowableStress;
EditText selectedPipeClass;
EditText selectedWeldFactor;
EditText selectedTemperature;
EditText selectedTempFactor;
EditText selectedLocation;
EditText selectedDesignFactor;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Değerlerin girildiği textkutucuklarının eşleştirilmesi
designPressure = findViewById(R.id.designPressure);
corrosionAllowance = findViewById(R.id.corrosionAllowance);
pipeDiameter = findViewById(R.id.pipeDiameter);
selectedMaterial = findViewById(R.id.selectedMaterial);
selectedAllowableStress = findViewById(R.id.selectedAllowableStress);
selectedPipeClass = findViewById(R.id.selectedPipeClass);
selectedWeldFactor = findViewById(R.id.selectedWeldFactor);
selectedTemperature = findViewById(R.id.selectedTemperature);
selectedTempFactor = findViewById(R.id.selectedTempFactor);
selectedLocation = findViewById(R.id.selectedLocation);
selectedDesignFactor = findViewById(R.id.selectedDesignFactor);
}
@Override
public void onResume(){
super.onResume();
Intent intent = getIntent();
//Malzeme sayfasından bilgi alan kısım
String selectedM = intent.getStringExtra("Material");
selectedMaterial.setText(selectedM);
String selectedAS = intent.getStringExtra("Allowable Stress");
selectedAllowableStress.setText(selectedAS);
//WeldFactor sayfasından bilgi alan kısım
String weldFactors = intent.getStringExtra("Type");
selectedPipeClass.setText(weldFactors);
String eFactor = intent.getStringExtra("eFactor");
selectedWeldFactor.setText(eFactor);
// TempFactor sayfasından bilgi alan kısım
String selectedTF = intent.getStringExtra("selectedTFactor");
selectedTempFactor.setText(selectedTF);
String selectedDT = intent.getStringExtra("selectedDTemp");
selectedTemperature.setText(selectedDT);
}
//SelectMaterial tuşuna basınca MaterialList sayfasına giden toMAterialList onclick metodu
public void toMaterialList(View view){
Intent intentMaterial = new Intent(MainActivity.this, MaterialList.class);
startActivity(intentMaterial);
}
//SelectWeldFactor tuşuna basınca WeldFactor sayfasına giden toWeldFactor onclick metodu
public void toWeldFactor(View view){
Intent intentWeldFactor = new Intent(MainActivity.this, WeldFactor.class);
startActivity(intentWeldFactor);
}
//SelectTempFactor tuşuna basınca TempFactor sayfasına giden toTempFactor onclick metodu
public void toTempFactor(View view){
Intent intentTempFactor = new Intent(MainActivity.this, TempFactor.class);
startActivity(intentTempFactor);
}
public void toDesignFactor(View view){
Intent intentdesignFactor = new Intent(MainActivity.this, DesignFactor.class);
startActivity(intentdesignFactor);
}
public void calculate(View view){
}
}
问题是您无法将数据从 activity B 发送到 activity A。如果需要,您必须使用 startActivityForResult
。您不能从被销毁的 activity 中获取数据 .
最适合您的方法是使用 sharedpreferences
.
//主要Activity
public class MainActivity extends AppCompatActivity {
public static final String MyPREFERENCES = "MyPrefs" ;
public static final String selectedMaterial = "selectedMaterial";
public static final String selectedAllowableStress = "selectedAllowableStress";
public static final String selectedTemperature = "selectedTemperature";
// For get strings
public static final String _selectedTemperature;
public static final String _selectedAllowableStress;
public static final String _selectedMaterial;
SharedPreferences sharedpreferences;
@Override
public void onResume(){
super.onResume();
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedpreferences.edit();
_selectedMaterial=editor.getString(selectedMaterial, "");
_selectedAllowableStress=editor.getString(selectedAllowableStress, "");
_selectedTemperature=editor.getString(selectedTemperature, "");
editor.commit();
}
}
//Activity一个
public class ActivityA extends AppCompatActivity {
public static final String MyPREFERENCES = "MyPrefs" ;
SharedPreferences sharedpreferences;
public static final String selectedMaterial = "selectedMaterial";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_a);
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedpreferences.edit();
editor.putString(selectedMaterial, "material");
editor.commit();
}
}
//ActivityB
public class ActivityB extends AppCompatActivity {
public static final String MyPREFERENCES = "MyPrefs" ;
SharedPreferences sharedpreferences;
public static final String selectedMaterial = "selectedAllowableStress";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_b);
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedpreferences.edit();
editor.putString(selectedAllowableStress, "allow");
editor.commit();
}
}
我是 android 编程的新手,我想我遇到了一个非常基本的问题。实际上在 Whosebug 上搜索了两天,但我无法找到适合我情况的解决方案。 所以总而言之,我尝试申请一个计算。 我有 5 个活动:MainActivity、ActivityA(selecting 一些东西并从 ArrayList 中获取价值),ActivityB(再次 selecting 一些东西并获取来自 ArrayList 的值),ActivityC(输入值并取另一个值),Activity D(输入值并取另一个值) 然后在 Mainactivity 上,这些值将用于方程式。
我通过使用意图获取值,并在 onresume 中对意图进行编码。 首先,我转到 ActivityA 和 select 我想要的,然后 return 回到 Mainactivity 并且我有所需的值,但是当我为 ActivityB 和 return 回到 Mainactivity,我丢失了 ActivityA 的值,因为我认为程序也会为 ActivityA 再次执行意图(这对所有其他活动都是一样的)。所以我认为我需要以某种方式将所有活动的意图分开。我尝试使用 sharedpreferences 或在所有具有不同值的活动上创建相同的字符串,以便在 onresume 部分的 if 或 switch 案例中使用,不幸的是我没有成功。
public class MainActivity extends AppCompatActivity {
//Değerlerin girildiği text kutucuklarının tanımlanması
EditText designPressure;
EditText corrosionAllowance;
EditText pipeDiameter;
EditText selectedMaterial;
EditText selectedAllowableStress;
EditText selectedPipeClass;
EditText selectedWeldFactor;
EditText selectedTemperature;
EditText selectedTempFactor;
EditText selectedLocation;
EditText selectedDesignFactor;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Değerlerin girildiği textkutucuklarının eşleştirilmesi
designPressure = findViewById(R.id.designPressure);
corrosionAllowance = findViewById(R.id.corrosionAllowance);
pipeDiameter = findViewById(R.id.pipeDiameter);
selectedMaterial = findViewById(R.id.selectedMaterial);
selectedAllowableStress = findViewById(R.id.selectedAllowableStress);
selectedPipeClass = findViewById(R.id.selectedPipeClass);
selectedWeldFactor = findViewById(R.id.selectedWeldFactor);
selectedTemperature = findViewById(R.id.selectedTemperature);
selectedTempFactor = findViewById(R.id.selectedTempFactor);
selectedLocation = findViewById(R.id.selectedLocation);
selectedDesignFactor = findViewById(R.id.selectedDesignFactor);
}
@Override
public void onResume(){
super.onResume();
Intent intent = getIntent();
//Malzeme sayfasından bilgi alan kısım
String selectedM = intent.getStringExtra("Material");
selectedMaterial.setText(selectedM);
String selectedAS = intent.getStringExtra("Allowable Stress");
selectedAllowableStress.setText(selectedAS);
//WeldFactor sayfasından bilgi alan kısım
String weldFactors = intent.getStringExtra("Type");
selectedPipeClass.setText(weldFactors);
String eFactor = intent.getStringExtra("eFactor");
selectedWeldFactor.setText(eFactor);
// TempFactor sayfasından bilgi alan kısım
String selectedTF = intent.getStringExtra("selectedTFactor");
selectedTempFactor.setText(selectedTF);
String selectedDT = intent.getStringExtra("selectedDTemp");
selectedTemperature.setText(selectedDT);
}
//SelectMaterial tuşuna basınca MaterialList sayfasına giden toMAterialList onclick metodu
public void toMaterialList(View view){
Intent intentMaterial = new Intent(MainActivity.this, MaterialList.class);
startActivity(intentMaterial);
}
//SelectWeldFactor tuşuna basınca WeldFactor sayfasına giden toWeldFactor onclick metodu
public void toWeldFactor(View view){
Intent intentWeldFactor = new Intent(MainActivity.this, WeldFactor.class);
startActivity(intentWeldFactor);
}
//SelectTempFactor tuşuna basınca TempFactor sayfasına giden toTempFactor onclick metodu
public void toTempFactor(View view){
Intent intentTempFactor = new Intent(MainActivity.this, TempFactor.class);
startActivity(intentTempFactor);
}
public void toDesignFactor(View view){
Intent intentdesignFactor = new Intent(MainActivity.this, DesignFactor.class);
startActivity(intentdesignFactor);
}
public void calculate(View view){
}
}
问题是您无法将数据从 activity B 发送到 activity A。如果需要,您必须使用 startActivityForResult
。您不能从被销毁的 activity 中获取数据 .
最适合您的方法是使用 sharedpreferences
.
//主要Activity
public class MainActivity extends AppCompatActivity {
public static final String MyPREFERENCES = "MyPrefs" ;
public static final String selectedMaterial = "selectedMaterial";
public static final String selectedAllowableStress = "selectedAllowableStress";
public static final String selectedTemperature = "selectedTemperature";
// For get strings
public static final String _selectedTemperature;
public static final String _selectedAllowableStress;
public static final String _selectedMaterial;
SharedPreferences sharedpreferences;
@Override
public void onResume(){
super.onResume();
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedpreferences.edit();
_selectedMaterial=editor.getString(selectedMaterial, "");
_selectedAllowableStress=editor.getString(selectedAllowableStress, "");
_selectedTemperature=editor.getString(selectedTemperature, "");
editor.commit();
}
}
//Activity一个
public class ActivityA extends AppCompatActivity {
public static final String MyPREFERENCES = "MyPrefs" ;
SharedPreferences sharedpreferences;
public static final String selectedMaterial = "selectedMaterial";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_a);
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedpreferences.edit();
editor.putString(selectedMaterial, "material");
editor.commit();
}
}
//ActivityB
public class ActivityB extends AppCompatActivity {
public static final String MyPREFERENCES = "MyPrefs" ;
SharedPreferences sharedpreferences;
public static final String selectedMaterial = "selectedAllowableStress";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_b);
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedpreferences.edit();
editor.putString(selectedAllowableStress, "allow");
editor.commit();
}
}