Question

这是头等舱

package com.example.jishwanth.three.students_file;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.Button;
import android.widget.EditText;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.example.jishwanth.three.R;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;



public class Students_list extends AppCompatActivity {


//this is the JSON Data URL
//make sure you are using the correct ip else it will not work
String name;
String tokenno;



private final String URL_PRODUCTS = "http://10.42.0.1/PHP/student_view.php?first_name="+name+"&token_no="+tokenno;

//a list to store all the products
List<Product> productList;

//the recyclerview
RecyclerView recyclerView;




@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.student_in);
    Intent intent = getIntent();
    name = intent.getStringExtra("name");
    tokenno = intent.getStringExtra("tokenno");




    //getting the recyclerview from xml
    recyclerView = findViewById(R.id.recylcerView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));

    //initializing the productlist
    productList = new ArrayList<>();

    //this method will fetch and parse json
    //to display it in recyclerview
    loadProducts();

}

private void loadProducts() {

    /*
    * Creating a String Request
    * The request type is GET defined by first parameter
    * The URL is defined in the second parameter
    * Then we have a Response Listener and a Error Listener
    * In response listener we will get the JSON response as a String
    * */
    StringRequest stringRequest = new StringRequest(Request.Method.GET, URL_PRODUCTS,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    try {
                        //converting the string to json array object
                        JSONArray array = new JSONArray(response);

                        //traversing through all the object
                        for (int i = 0; i < array.length(); i++) {

                            //getting product object from json array
                            JSONObject product = array.getJSONObject(i);

                            //adding the product to product list
                            productList.add(new Product(
                                    product.getString("first_name"),
                                    product.getString("token_no"),
                                    product.getString("entered_out_time"),
                                    product.getString("approved_from"),
                                    product.getString("reason"),
                                    product.getString("image"),
                                    product.getString("entered_in_time"),
                                    product.getString("s_date")

                            ));
                        }

                        //creating adapter object and setting it to recyclerview
                        v_ProductsAdapter adapter = new v_ProductsAdapter(Students_list.this, productList);
                        recyclerView.setAdapter(adapter);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    //adding our stringrequest to queue
    Volley.newRequestQueue(this).add(stringRequest);
}
}

这是第二类

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.example.jishwanth.three.R;

import com.example.jishwanth.three.students_file.Students_list;
public class Student_view extends AppCompatActivity {

Button button;
EditText editText1,editText2;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.student_view);
    addListenerOnButton();
}

public void addListenerOnButton() {

    final Context context = this;

    button = (Button) findViewById(R.id.button6);
    editText1=findViewById(R.id.editText8);
    editText2=findViewById(R.id.editText9);
    button.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {

            Intent intent = new Intent(context, Students_list.class);
            intent.putExtra("name", editText1.getText().toString());
            intent.putExtra("tokenno", editText2.getText().toString());

            startActivity(intent);
        }

    });

}

}

从我的第二个类iam传递值到第一个类，但值在String URL_PRODUCTS执行后传递，但我想在字符串URL_PRODUCTS执行之前接收值。如果我添加

Intent intent = getIntent();
name = intent.getStringExtra("name");
tokenno = intent.getStringExtra("tokenno");

这个私有字符串之前URL_PRODUCTS我得到错误是否有任何方法可以将名称和tokenno添加到字符串URL_PRODUCTS

Answer 1

试试这种方式

package com.example.jishwanth.three.students_file;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.Button;
import android.widget.EditText;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.example.jishwanth.three.R;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;



public class Students_list extends AppCompatActivity {


//this is the JSON Data URL
//make sure you are using the correct ip else it will not work
String name;
String tokenno;



private String URL_PRODUCTS;

//a list to store all the products
List<Product> productList;

//the recyclerview
RecyclerView recyclerView;




@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.student_in);
    Intent intent = getIntent();
    name = intent.getStringExtra("name");
    tokenno = intent.getStringExtra("tokenno");

    URL_PRODUCTS = "http://10.42.0.1/PHP/student_view.php?first_name="+name+"&token_no="+tokenno;


    //getting the recyclerview from xml
    recyclerView = findViewById(R.id.recylcerView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));

    //initializing the productlist
    productList = new ArrayList<>();

    //this method will fetch and parse json
    //to display it in recyclerview
    loadProducts();

}

private void loadProducts() {

    /*
    * Creating a String Request
    * The request type is GET defined by first parameter
    * The URL is defined in the second parameter
    * Then we have a Response Listener and a Error Listener
    * In response listener we will get the JSON response as a String
    * */
    StringRequest stringRequest = new StringRequest(Request.Method.GET, URL_PRODUCTS,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    try {
                        //converting the string to json array object
                        JSONArray array = new JSONArray(response);

                        //traversing through all the object
                        for (int i = 0; i < array.length(); i++) {

                            //getting product object from json array
                            JSONObject product = array.getJSONObject(i);

                            //adding the product to product list
                            productList.add(new Product(
                                    product.getString("first_name"),
                                    product.getString("token_no"),
                                    product.getString("entered_out_time"),
                                    product.getString("approved_from"),
                                    product.getString("reason"),
                                    product.getString("image"),
                                    product.getString("entered_in_time"),
                                    product.getString("s_date")

                            ));
                        }

                        //creating adapter object and setting it to recyclerview
                        v_ProductsAdapter adapter = new v_ProductsAdapter(Students_list.this, productList);
                        recyclerView.setAdapter(adapter);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    //adding our stringrequest to queue
    Volley.newRequestQueue(this).add(stringRequest);
}
}

在onCreate()方法中创建您的URL_PRODUCTS。在您的代码中，您从onCreate()中的intent中获取值，但是在调用onCreate()之前您正在分配它们，这是错误的。

无法在android studio中设置字符串值

1 个答案: