我这样声明变量“ title”：
static String title;
此title应该出现在警报生成器中。当我显示警报生成器时，它第一次给我（标题）一个空值，而第二次给我一个真实值。
我在handleResult（Result结果）中实现两个方法后创建了一个构建器
每个人都应该与数据库建立连接（来自不同的表和不同的PHP函数）。另外，我需要按此顺序实施 如何解决这个问题？
package com.example.lenovo.tactic4;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.os.Build;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.google.zxing.Result;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import me.dm7.barcodescanner.zxing.ZXingScannerView;
import static android.Manifest.permission.CAMERA;
import android.content.Intent;
public class ScanActivity extends AppCompatActivity implements ZXingScannerView.ResultHandler{
private static final int REQUEST_CAMERA = 1;
private ZXingScannerView scannerView;
String Attendee_ID;
InputStream is=null;
String result=null;
String line=null;
private static int camId = Camera.CameraInfo.CAMERA_FACING_BACK;
int code;
boolean updateFinish = false;
public String eventID,subevent_ID;
String attendeeName;
private String URL_Scan_Update="http://192.168.1.5/phpApp/updateScanApp.php";
String URL_AttendeeName= "http://192.168.1.5/phpApp/getAttNameApp.php?Attendee_ID=";
static String title ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_scan);
eventID = getIntent().getExtras().getString("eventID","");
subevent_ID = getIntent().getExtras().getString("eventIdSubSelect","");
scannerView = new ZXingScannerView(this);
setContentView(scannerView);
int currentApiVersion = Build.VERSION.SDK_INT;
if(currentApiVersion >= Build.VERSION_CODES.M)
{
if(checkPermission())
{
// Toast.makeText(getApplicationContext(), "Permission already granted!", Toast.LENGTH_LONG).show();
}
else
{
requestPermission();
}
}
}
private boolean checkPermission()
{
return (ContextCompat.checkSelfPermission(getApplicationContext(), CAMERA) == PackageManager.PERMISSION_GRANTED);
}
private void requestPermission()
{
ActivityCompat.requestPermissions(this, new String[]{CAMERA}, REQUEST_CAMERA);
}
@Override
public void onResume() {
super.onResume();
int currentapiVersion = android.os.Build.VERSION.SDK_INT;
if (currentapiVersion >= android.os.Build.VERSION_CODES.M) {
if (checkPermission()) {
if(scannerView == null) {
scannerView = new ZXingScannerView(this);
setContentView(scannerView);
}
scannerView.setResultHandler(this);
scannerView.startCamera();
} else {
requestPermission();
}
}
}
@Override
public void onDestroy() {
super.onDestroy();
scannerView.stopCamera();
}
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case REQUEST_CAMERA:
if (grantResults.length > 0) {
boolean cameraAccepted = grantResults[0] == PackageManager.PERMISSION_GRANTED;
if (cameraAccepted){
Toast.makeText(getApplicationContext(), "Permission Granted, Now you can access camera", Toast.LENGTH_LONG).show();
}else {
Toast.makeText(getApplicationContext(), "Permission Denied, You cannot access and camera", Toast.LENGTH_LONG).show();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (shouldShowRequestPermissionRationale(CAMERA)) {
showMessageOKCancel("You need to allow access to both the permissions",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(new String[]{CAMERA},
REQUEST_CAMERA);
}
}
});
return;
}
}
}
}
break;
}
}
private void showMessageOKCancel(String message, DialogInterface.OnClickListener okListener) {
new android.support.v7.app.AlertDialog.Builder(ScanActivity.this)
.setMessage(message)
.setPositiveButton("OK", okListener)
.setNegativeButton("Cancel", null)
.create()
.show();
}
@Override
public void handleResult(Result result) {
Attendee_ID = result.getText();
// Log.d("QRCodeScanner", result.getText());
// Log.d("QRCodeScanner", result.getBarcodeFormat().toString());
getAttName();
update(eventID,Attendee_ID,subevent_ID);
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setNegativeButton("cancel", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
finish();
}
});
builder.setPositiveButton("yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
Intent intent = new Intent(ScanActivity.this, PrintActivity.class);
intent.putExtra("event_ID", eventID);
intent.putExtra("Attendee_ID", Attendee_ID);
startActivity(intent);
}
});
builder.setMessage(title + "\n" + "do you want to print?");
builder.create().show();
}
private void update( final String event_ID ,final String Attendee_ID ,final String subevent_ID) {
RequestQueue queue = Volley.newRequestQueue(this);
StringRequest postRequest = new StringRequest(Request.Method.POST, URL_Scan_Update,
new Response.Listener<String>()
{
@Override
public void onResponse(String response) {
Log.d("Update: ",""+response);
try {
JSONObject jsonObject = new JSONObject(response);
if(jsonObject.getInt("value")==1){
title = "welcome " +attendeeName +" login successful ";
}
else {
title = "welcome " +attendeeName +" you already login ";
}
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener()
{
@Override
public void onErrorResponse(VolleyError error) {
// error
Toast.makeText(ScanActivity.this,"Error",Toast.LENGTH_LONG).show();
}
}
) {
@Override
protected Map<String, String> getParams()
{
Map<String, String> params = new HashMap<String, String>();
params.put("event_ID", event_ID);
params.put("Attendee_ID", Attendee_ID);
params.put("subevent_ID", subevent_ID);
return params;
}
};
queue.add(postRequest);
}
private void getAttName(){
StringRequest stringRequest = new StringRequest(Request.Method.GET,
URL_AttendeeName+Attendee_ID,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONObject jObj = new JSONObject(response);
attendeeName = jObj.getString("name");
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
if(error != null){
Toast.makeText(getApplicationContext(), "Something went wrong.", Toast.LENGTH_LONG).show();
}
}
}
);
MySingleton.getInstance(getApplicationContext()).addToRequestQueue(stringRequest);
}
public void onPointerCaptureChanged(boolean hasCapture) {
}
}
答案 0 :(得分：0)
当您在<td>
{{$participant->vt_avg}},
@if($participant->vt_avg > 85)
x
@else
y
@endif
</td>
内调用update()时，将启动一个新的异步网络调用，并在handleResult()上更新标题。
但是这里要注意的是，网络调用发生在后台线程上，当调用完成时，您会在活动中收到onResponse()方法回调。
要解决此问题，
onResponse()删除警报对话框调用handleResult()方法内部调用警报对话框编辑：
示例：
onResponse()（仍然可能存在一些简单的错误，例如变量命名或访问，请尝试解决它们，因为我没有完整的代码）