当我解析json时应用程序崩溃

Question

在我的MainActivity.java

中

<a>

我的DisplayListView.java                     包rjj.tutorial_jsonandlistview;

    package rjj.tutorial_jsonandlistview;

    import android.content.Intent;
    import android.os.AsyncTask;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.TextView;
    import android.widget.Toast;

    import org.w3c.dom.Text;
    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.net.HttpURLConnection;
    import java.net.MalformedURLException;
    import java.net.URL;

        public class MainActivity extends AppCompatActivity {

        String Json_STRING;

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

        public void getJSON(View view) {

            new BackgroundTask().execute();

        }



        class BackgroundTask extends AsyncTask<Void, Void, String>{

            String json_url;
            String JSON_STRING;
            @Override
            protected void onPreExecute() {
                json_url = "http://kreen155.000webhostapp.com/rizal.php";
            }    

            @Override
            protected String doInBackground(Void... params) {
                try {
                    URL url = new URL(json_url);
                    HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
                    InputStream inputStream = httpURLConnection.getInputStream();
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                    StringBuilder stringBuilder = new StringBuilder();
                    while ((JSON_STRING = bufferedReader.readLine()) != null) {

                        stringBuilder.append(JSON_STRING+"\n");
                    }

                    bufferedReader.close();
                    inputStream.close();
                    httpURLConnection.disconnect();
                    return stringBuilder.toString().trim();
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }

                return null;
            }

            @Override
            protected void onProgressUpdate(Void... values) {
                super.onProgressUpdate(values);
            }

            @Override
            protected void onPostExecute(String result) {
                TextView textView = (TextView)findViewById(R.id.textView2);
                textView.setText(result);
                Json_STRING = result;
            }
        }
    //List view time!
        public void parseJSON(View view) {

            if(Json_STRING == null){
                Toast.makeText(getApplicationContext(), "First Get JSON", Toast.LENGTH_SHORT).show();
            }else{
                Intent intent = new Intent(this, DisplayListView.class);
                intent.putExtra("json_data", Json_STRING);
                startActivity(intent);
            }

        }

    }

在我的ContactAdapter.java

中

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;

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

public class DisplayListView extends AppCompatActivity {

    String json_string;
    JSONObject jsonObject;
    JSONArray jsonArray;
    ContactAdapter contactAdapter;
    ListView listView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.display_listview_layout);
        listView = (ListView)findViewById(R.id.listview);

        contactAdapter = new ContactAdapter(this,R.layout.row_layout);
        listView.setAdapter(contactAdapter);
        json_string = getIntent().getExtras().getString("json_data");

        try {
            jsonObject = new JSONObject(json_string);
            jsonArray = jsonObject.getJSONArray("server_response");
            int count = 0;
            String id ,firstname , surname, age , username, password;


            while(count<jsonObject.length()){
                JSONObject JO = jsonArray.getJSONObject(count);
                id = JO.getString("id");
                firstname = JO.getString("firstname");
                surname = JO.getString("surname");
                age = JO.getString("age");
                username = JO.getString("username");
                password = JO.getString("password");
                Contacts contact = new Contacts(id, firstname, surname, age,username,password);
                contactAdapter.add(contact);


                count++;

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

    }
}

在我的AndroidManifest.xml

中

package rjj.tutorial_jsonandlistview;

import android.content.Context;
import android.support.annotation.LayoutRes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

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

/**
 * Created by Julian on 7/20/2017.
 */

public class ContactAdapter extends ArrayAdapter {
    List list = new ArrayList();
    public ContactAdapter(@NonNull Context context, @LayoutRes int resource) {
        super(context, resource);
    }


    public void add(Contacts object) {
        super.add(object);
        list.add(object);
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Nullable
    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {

        View row;
        row = convertView;
        ContactHolder contactHolder;
        if(row == null){
            LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            row = layoutInflater.inflate(R.layout.row_layout,parent,false);
            contactHolder = new ContactHolder();
            contactHolder.tx_id = (TextView)row.findViewById(R.id.tx_id);
            contactHolder.tx_firstname = (TextView)row.findViewById(R.id.tx_firstname);
            contactHolder.tx_surname = (TextView)row.findViewById(R.id.tx_surname);
            contactHolder.tx_username = (TextView)row.findViewById(R.id.tx_username);
            contactHolder.tx_password = (TextView)row.findViewById(R.id.tx_password);
            row.setTag(contactHolder);

        } else{
            contactHolder = (ContactHolder)row.getTag();
        }
        Contacts contacts = (Contacts)this.getItem(position);
        contactHolder.tx_id.setText(contacts.getId());
        contactHolder.tx_firstname.setText(contacts.getFirstname());
        contactHolder.tx_surname.setText(contacts.getSurname());
        contactHolder.tx_age.setText(contacts.getAge());
        contactHolder.tx_username.setText(contacts.getUsername());
        contactHolder.tx_password.setText(contacts.getPassword());
        return row;
    }

    static class ContactHolder{
        TextView tx_id, tx_firstname, tx_surname, tx_age, tx_username, tx_password;
    }
}

在我的gradle构建中

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="rjj.tutorial_jsonandlistview">

    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".DisplayListView"></activity>
    </application>

</manifest>

另一个gradle构建

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion "26.0.0"
    defaultConfig {
        applicationId "rjj.tutorial_jsonandlistview"
        minSdkVersion 19
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.3.1'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'
}

首次启动/打开崩溃日志：

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

单击解析JSON时：

07-20 23:34:40.668 6438-6438/rjj.tutorial_jsonandlistview E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering
07-20 23:34:41.398 6438-6438/rjj.tutorial_jsonandlistview E/EGL_emulation: tid 6438: eglSurfaceAttrib(1199): error 0x3009 (EGL_BAD_MATCH)

我现在不知道该怎么做，我已经尝试了3个教程，但都徒劳无功。请帮助我的代码出现问题。

Answer 1

错误来自这行代码：

contactHolder.tx_age.setText(contacts.getAge());

你没有添加

contactHolder.tx_age = (TextView)row.findViewById(R.id.tx_age);

在此代码中：

if(row == null){
            LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            row = layoutInflater.inflate(R.layout.row_layout,parent,false);
            contactHolder = new ContactHolder();
            contactHolder.tx_id = (TextView)row.findViewById(R.id.tx_id);
            contactHolder.tx_firstname = (TextView)row.findViewById(R.id.tx_firstname);
            contactHolder.tx_surname = (TextView)row.findViewById(R.id.tx_surname);
            contactHolder.tx_username = (TextView)row.findViewById(R.id.tx_username);
            contactHolder.tx_password = (TextView)row.findViewById(R.id.tx_password);
            row.setTag(contactHolder);