java - 当用户单击按钮时，无法在我的 textView 中显示特定的 JSON 数据

Question

开始学习 java 和 android 开发，但我仍然在将 JSON 数据从 URL 显示到 textview 时遇到一些困难。基本上我要做的是当用户在查找字段中键入并单击查找按钮时，数据将显示他们在文本视图中键入的特定项目。任何建议或建议都会有所帮助。谢谢你。

这是我的主要活动：

import java.net.MalformedURLException;
import java.net.URL;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.alexanderherrera.data.JsonDataClass;
import com.alexanderherrera.data.WebConnectClass;
import com.alexanderherrera.elements.AppElements;

import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;



public class MainActivity extends Activity {

Context context;

LinearLayout baseLinearLayout;
LinearLayout.LayoutParams baseLayoutParams;

TextView mainTextView;
EditText userInputText;

Button findButton;

String urlApiJsonString;

static TextView urlAPIJsonTextView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    context = this;

    baseLinearLayout = AppElements.getBaseLayout(context);

    mainTextView = AppElements.getMainTextView(context);

    urlAPIJsonTextView = AppElements.getJsonTextView(context);

    if (WebConnectClass.getConnectionStatus(context)) {//If true.
        getUrlApiData apiData = new getUrlApiData();
        apiData.execute(JsonDataClass.urlApiStringLink);

        //urlApiJsonString = JsonDataClass.onPostExecute(JsonDataClass.urlApiStringLink);
    } else {
        urlAPIJsonTextView.setText("There was No Connection!");
    }

    userInputText = AppElements.getUserInputText(context);
    userInputText.setHint("Enter App Name or Genre Type");


    findButton = AppElements.getFindEditTextButton(context);
    findButton.setText("Find");
    findButton.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            //Get the text inputed by the user:
            String userInput = userInputText.getText().toString();

        }
    });


    baseLinearLayout.addView(mainTextView);
    baseLinearLayout.addView(userInputText);
    baseLinearLayout.addView(findButton);
    baseLinearLayout.addView(urlAPIJsonTextView);

    setContentView(baseLinearLayout);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

static class getUrlApiData extends AsyncTask<String, Void, String> {

    @Override
    protected String doInBackground(String... params) {
        String urlApiResponseString = "";
        try {
            URL urlApi = new URL(JsonDataClass.urlApiStringLink);
            urlApiResponseString = JsonDataClass.getUrlApiResponse(urlApi);
        } catch (MalformedURLException e) {
            urlApiResponseString = "Another ERROR has occurred!";
            Log.e(WebConnectClass.TAG,"ERROR!!!", e);
        }

        return urlApiResponseString;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        String jsonResult = "";
        String artistNameString = "";
        String isGameCenterEnabledString = "";
        String priceString = "";
        String versionString = "";
        String primaryGenreNameString = "";
        String averageUserRatingString = "";
        try {
            @SuppressWarnings("static-access")
            JSONArray iosAppJSONArray = new JSONArray(result.valueOf("results"));
            int i;
            for (i = 0; i < iosAppJSONArray.length(); i++) {
                JSONObject iosAppJSONObject = iosAppJSONArray.getJSONObject(i);

                artistNameString = iosAppJSONObject.getString("artistName");
                isGameCenterEnabledString = iosAppJSONObject.getString("isGameCenterEnabled");
                priceString = iosAppJSONObject.getString("price");
                versionString = iosAppJSONObject.getString("version");
                primaryGenreNameString = iosAppJSONObject.getString("primaryGenreName");
                averageUserRatingString = iosAppJSONObject.getString("averageUserRating");

                jsonResult = "Artist Name: " + artistNameString;
                urlAPIJsonTextView.setText(jsonResult);
            }
        } catch (JSONException e) {

        }

    }
}

}

这个类是我创建文本视图、按钮和编辑文本的地方：

package com.alexanderherrera.elements;

import android.content.Context;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.LinearLayout.LayoutParams;
import android.widget.TextView;

public class AppElements {

public static LinearLayout getBaseLayout(Context context) {
    // Initialize Linear Layout One:
    LinearLayout baseLayout = new LinearLayout(context);
    baseLayout.setOrientation(LinearLayout.VERTICAL);
    LayoutParams baseParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
    baseLayout.setLayoutParams(baseParams);

    return baseLayout;

}

public static TextView getMainTextView(Context context) {
    TextView mainTextView = new TextView(context);
    LayoutParams baseParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
    mainTextView.setLayoutParams(baseParams);
    mainTextView.setText("Browse through the selection of IOS games in the appstore.");
    mainTextView.setTextSize(24.0f);

    return mainTextView;
}

public static TextView getJsonTextView(Context context) {
    TextView jsonTextView = new TextView(context);
    LayoutParams baseParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
    jsonTextView.setLayoutParams(baseParams);
    jsonTextView.setTextSize(12.0f);

    return jsonTextView;
}

public static EditText getUserInputText(Context context) {
    EditText userInputText = new EditText(context);
    LayoutParams baseParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
    userInputText.setLayoutParams(baseParams);

    return userInputText;
}

public static Button getFindEditTextButton(Context context) {
    Button findButton = new Button(context);
    LayoutParams baseParams = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
    findButton.setLayoutParams(baseParams);

    return findButton;
}


}

JSON数据类：

package com.alexanderherrera.data;

import java.io.BufferedInputStream;
import java.net.URL;
import java.net.URLConnection;

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

import com.alexanderherrera.iosgamesinfo.MainActivity;

import android.util.Log;

public class JsonDataClass {

public static String urlApiStringLink = "http://itunes.apple.com/search?term=app&term=toppaid&entity=software";
private final String artistNameString;
private final String isGameCenterEnabledString;
private final String priceString;
private final String versionString;
private final String primaryGenreNameString;
private final String averageUserRating;

private JsonDataClass(String artistNameString, String isGameCenterEnabledString, String priceString, String versionString, String primaryGenreNameString, String averageUserRating) {
    this.artistNameString = artistNameString;
    this.isGameCenterEnabledString = isGameCenterEnabledString;
    this.priceString = priceString;
    this.versionString = versionString;
    this.primaryGenreNameString = primaryGenreNameString;
    this.averageUserRating = averageUserRating;
}

public String setArtistNameString() {
    return artistNameString;
}

public String setIsGameCenterEnabledString() {
    return isGameCenterEnabledString;
}

public String setPriceString() {
    return priceString;
}

public String setVersionString() {
    return versionString;
}

public String setPrimaryGenreNameString() {
    return primaryGenreNameString;
}

public String setAverageUserRating() {
    return averageUserRating;
}

public static String getUrlApiResponse(URL iosAppUrl) {
    String urlApiResponse = "";

    try {
        URLConnection iosAppURLConnection = iosAppUrl.openConnection();
        BufferedInputStream iosAppBuffInputStream = new BufferedInputStream(iosAppURLConnection.getInputStream());
        byte[] iosAppBytes = new byte[1024];
        int bytesRead = 0;
        StringBuffer responseBuff = new StringBuffer();//Use StringBuffer to append.
        while ((bytesRead = iosAppBuffInputStream.read(iosAppBytes)) != -1) {
            urlApiResponse = new String(iosAppBytes, 0, bytesRead);
            responseBuff.append(urlApiResponse);
        }
        urlApiResponse = responseBuff.toString();
        Log.i(WebConnectClass.TAG, urlApiResponse);
    } catch (Exception e) {
        urlApiResponse = "An ERROR has occurred!!";
        Log.e(WebConnectClass.TAG, "There was an ERROR with the URL API Response!");
    }
    return urlApiResponse;
}

}