java - 将两个值作为字符串传递给同一 Activity 会返回一个值 null

Question

这是我的代码，用于显示两个值:推荐的胰岛素剂量和注入(inject)的胰岛素剂量。这两个值被传递给另一个 Activity 。

我使用了两个 Intent 将两个值传递给另一个 Activity (NewActivity)。

问题是，当使用两个 Intent 时，仅显示一个值。输出显示为:

Recommended insulin dosage:null, Administered insulin dosage:10 (correct value of the calculation).

如果从button.setOnClickListener中删除startActivity(intent)，输出将显示为:

Recommended insulin dosage:23 (correct value), Administered insulin dosage:null.

其中一个值正在变为 null。如何显示两个值？

我也尝试将字符串声明为公共(public)

MainActivity.java

public class MainActivity extends Activity implements View.OnClickListener {

public static final int DIALOG_DOWNLOAD_PROGRESS = 0;
private Button startBtn;
private ProgressDialog mProgressDialog;
private Button button;
private Button button2;
private EditText editText;
private EditText editText2;
private EditText editText4;
public static String myid;
public static String insulin;
private Spinner dynamicSpinner;
private ProgressDialog loading;





   @Override
   protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Intent intent=getIntent();
    String carbval=intent.getStringExtra("carbval");

    final EditText editText2 = (EditText) findViewById(R.id.editText2);
    editText2.setText(carbval);
    dynamicSpinner = (Spinner) findViewById(R.id.dynamic_spinner);

    editText = (EditText) findViewById(R.id.editText);
    button2 = (Button) findViewById(R.id.button2);
    button = (Button) findViewById(R.id.button);

    editText4=(EditText) findViewById(R.id.editText4);




   button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            String carbohydrate = editText2.getText().toString().trim();
            String dailydose = editText4.getText().toString().trim();
            int cc = Integer.parseInt(carbohydrate);
            int dd = Integer.parseInt(dailydose);
            int goc = 450 / dd;
            int ab = cc / goc;
            myid = Integer.toString(ab);
            Intent intent1=new Intent(MainActivity.this,NewActivity.class);
            intent1.putExtra("ids",myid);
            startActivity(intent1);


        }
    });




Spinner staticSpinner = (Spinner) findViewById(R.id.static_spinner);

    // Create an ArrayAdapter using the string array and a default spinner
    ArrayAdapter<CharSequence> staticAdapter = ArrayAdapter
            .createFromResource(this, R.array.brew_array,
                    android.R.layout.simple_spinner_item);

    // Specify the layout to use when the list of choices appears
    staticAdapter
            .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

    // Apply the adapter to the spinner
    staticSpinner.setAdapter(staticAdapter);

    Spinner dynamicSpinner = (Spinner) findViewById(R.id.dynamic_spinner);

    String[] items = new String[] { "---SELECT---", "LOW", "MODERATE", "HIGH" };

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_spinner_item, items);

    dynamicSpinner.setAdapter(adapter);

    dynamicSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view,
                                   int position, long id) {
            Log.v("item", (String) parent.getItemAtPosition(position));
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
            // TODO Auto-generated method stub
        }
       });


    }




private void getData() {


    String bloodglucose = editText.getText().toString().trim();
    if (bloodglucose.equals("")) {
        Toast.makeText(this, "Please enter bloodglucose", Toast.LENGTH_LONG).show();
        return;
    }
    String dosage =dynamicSpinner.getSelectedItem().toString().trim();
    if (dosage.equals("")) {
        Toast.makeText(this, "Please enter dosage", Toast.LENGTH_LONG).show();
        return;
    }
    loading = ProgressDialog.show(this,"Please wait...","Calculating insulin dosage...",false,false);

    String url1 = "http://10.1.6.21/getData1.php?bloodglucose="+editText.getText().toString().trim()+"&dosage="+dynamicSpinner.getSelectedItem().toString().trim();


    StringRequest stringRequest = new StringRequest(url1, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            loading.dismiss();
            showJSON(response);
        }
     },
            new Response.ErrorListener() {

                @Override
                public void onErrorResponse(VolleyError error) {
                    Toast.makeText(MainActivity.this,error.getMessage().toString(),Toast.LENGTH_LONG).show();
                }
            });


    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(stringRequest);

     }

    private void showJSON(String response){

    String insulin="";



    try {
        JSONObject jsonObject = new JSONObject(response);
        JSONArray result = jsonObject.getJSONArray(Confignew.JSON_ARRAY);
        JSONObject collegeData = result.getJSONObject(0);

         insulin = collegeData.getString(Confignew.KEY_INSULIN);

        Intent intent1=new Intent(MainActivity.this,NewActivity.class);
        intent1.putExtra("value",insulin);

       startActivity(intent1);


       } catch (JSONException e) {
        e.printStackTrace();
       }


    }

    @Override
    public void onClick(View v) {
    getData();

    }

    }

NewActivity.java

public class NewActivity extends AppCompatActivity {

   private Button mBtGoBack;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_new);
    TextView tvmessage=(TextView) findViewById(R.id.tv_message);
    tvmessage.setText("Recommended Insulin Dosage:  "+getIntent().getExtras().getString("value"));

    TextView tvmessage1=(TextView) findViewById(R.id.tv_message1);
    tvmessage1.setText("Administered Insulin Dosage:  "+getIntent().getExtras().getString("ids"));
    mBtGoBack = (Button) findViewById(R.id.bt_go_back);

    mBtGoBack.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            finish();
        }
      });

      }
     }

Answer 1

查看您的代码，您似乎在开始 Activity 之前重新创建 Intent 。您创建的每个 Intent 只有一个值传递到 NewActivity.java。您需要将两个值添加到同一 Intent ，而不是重新创建它。

这是您的问题:

    Intent intent1=new Intent(MainActivity.this,NewActivity.class);
    intent1.putExtra("ids",myid);

    Intent intent1=new Intent(MainActivity.this,NewActivity.class);
    intent1.putExtra("value",insulin);

您应该只创建 Intent 一次，然后根据需要向其添加额外内容，而不是实例化两次。