Question

我想创建一个Android应用程序，它有多个活动，我传入数据然后将其发送到MainActivity。我想通过创建意图来传递数据，然后使用savedInstanceState存储它。如果我通过InformationA但是当我发送数据InfomationB与另一个意图时，它会很好地运行存储的信息。我也尝试过使用共享首选项。

我如何解决这个问题以及为什么要删除InformationA？

public class MainActivity extends AppCompatActivity {

String order = "Order \n";
String Order1;
String Order2;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    TextView warzywa = (TextView) findViewById(R.id.warzywa);
    warzywa.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick (View View){
            Intent idź_w = new Intent(MainActivity.this, vegetables_activity.class);
            startActivity(idź_w);
        }
    });
    TextView owoced = (TextView) findViewById(owoce);
    owoced.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick (View View){
            Intent idź_w = new Intent(MainActivity.this, Owoce.class);
            startActivity(idź_w);
        }
    });

    Button wysyłka = (Button) findViewById(R.id.zamówienie_całkowite);

    wysyłka.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick (View View){
              if (Order1==null && getIntent().getExtras().getString("WhatO")!=null)
              Order1 = getIntent().getExtras().getString("WhatO");
               if (Order2==null && getIntent().getExtras().getString("WhatV")!=null)
              Order2 = getIntent().getExtras().getString("WhatV");    
              order = order + Order1 + Order2;
              Toast.makeText(MainActivity.this, "" + order , Toast.LENGTH_SHORT).show();
        }
    });
}
public void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putString("Order1", Order1);
    savedInstanceState.putString("Order2", Order2);
    super.onSaveInstanceState(savedInstanceState);
}
public void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    Order1 = savedInstanceState.getString("Order1");
    Order2 = savedInstanceState.getString("Order2");
}}

1个儿童活动

public class vegetables_activity extends AppCompatActivity {
String Order = "";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_warzywa);
    final ArrayList<Produkt> vegetables = new ArrayList<>();
    vegetables.add(new Produkt("tomatoe", 0));
    vegetables.add(new Produkt("onion", 0));
    vegetables.add(new Produkt("potatoe", 0));

    New_Adapter adapter = new New_Adapter(this, vegetables);

    ListView listView = (ListView) findViewById(R.id.activity_vegetables);
    listView.setAdapter(adapter);

    Button order = (Button) findViewById(R.id.zamówienie_warzywne);
    order.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View View) {
            for (int z = 0; z < vegetables.size(); z++) {
                if (vegetables.get(z).getMquantity() != 0) {
                    Order = "" + Order + vegetables.get(z).getmNazwa_Warzywa() + " razy " + vegetables.get(z).getMquantity() + "\n";
                }
            }
            Context context = getApplicationContext();
            Toast.makeText(context, "OK", Toast.LENGTH_SHORT).show();
            Intent intent = new Intent(vegetables_activity.this, MainActivity.class);
            intent.putExtra("WhatV", Order);
            startActivity(intent);
        }
    });
}}

2个孩子的活动

public class Owoce extends AppCompatActivity {
String Order_Owoce = "";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_warzywa);
    final ArrayList<Produkt> vegetables = new ArrayList<>();
    vegetables.add(new Produkt("apple", 0));
    vegetables.add(new Produkt("banana", 0));
    vegetables.add(new Produkt("peach", 0));

    New_Adapter adapter = new New_Adapter(this, vegetables);

    ListView listView = (ListView) findViewById(R.id.activity_vegetables);
    listView.setAdapter(adapter);

    Button order = (Button) findViewById(R.id.zamówienie_warzywne);
    order.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View View) {
            for (int z = 0; z < vegetables.size(); z++) {
                if (vegetables.get(z).getMquantity() != 0) {
                    Order_Owoce = "" + Order_Owoce + vegetables.get(z).getmNazwa_Warzywa() + " razy " + vegetables.get(z).getMquantity() + "\n";
                }
            }
            Context context = getApplicationContext();
            Toast.makeText(context, "OK", Toast.LENGTH_SHORT).show();
            Intent intent = new Intent(Owoce.this, MainActivity.class);
            intent.putExtra("WhatO", Order_Owoce);
            startActivity(intent);
            }
    });
}
}

Answer 1

我想你可以尝试一个数组。将每条相关信息放在数组中的特定位置（应该在具有意图的活动之间转移），并且还发送具有意图的那条信息的索引，以便接收活动知道访问它的位置。

Answer 2

当您声明意图时，可以将Bundle中的参数从Activity传递到另一个Activity。

参见示例：

Intent intent = new Intent(this, AnotherActivity.class);
intent.putExtra("argKey", argValue);

但请注意，Bundle最多只能存储1MB，如果我没有弄错，那么当你需要传递一个巨大的数组时，尝试不同的方法，比如SharedPreferences或保存你想要保存的数据在DataManager单例类中，并在需要时检索它。

如何通过活动发送数据并保存，以供进一步使用？

2 个答案: