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();
}
});
}
}
最佳答案
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。
关于java - 将两个值作为字符串传递给同一 Activity 会返回一个值 null，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43648655/