java - 开始时带有按钮的布局

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我有这段代码。当我运行它时，它从JSON获取数据并显示。我想要一个XML布局，在应用程序的开始处带有一个名为“新闻”的按钮，当您单击该“新闻”按钮时，我想显示我的JSON数据。如何使用按钮添加该布局？

http://www.megafileupload.com/en/file/551807/AdaDerana-rar.html

这是我的源代码。

这是我的MainActivity类(class)

package com.example.adaderana;

import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;



public class MainActivity extends Activity  {
    // Declare Variables
    JSONObject jsonobject;
    JSONArray jsonarray;
    ListView listview;
    ListViewAdapter adapter;
    ProgressDialog mProgressDialog;
    ArrayList<HashMap<String, String>> arraylist;




    static String TITLE = "title";
    static String AUTHOR = "author";
    static String THUMBNAIL = "thumbnail";
    static String CONTENTS = "contents";
    static String IMAGE = "image";




    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Get the view from list_main.xml
        setContentView(R.layout.listview_main);

        // Execute DownloadJSON AsyncTask
     new DownloadJSON().execute();

}
   // DownloadJSON AsyncTask
    private class DownloadJSON extends AsyncTask<Void, Void, Void> {


 @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Create a progressdialog
            mProgressDialog = new ProgressDialog(MainActivity.this);
            // Set progressdialog title
            mProgressDialog.setTitle("Derana News");
            // Set progressdialog message
            mProgressDialog.setMessage("Loading...");
            mProgressDialog.setIndeterminate(false);
            // Show progressdialog
            mProgressDialog.show();
        }


        @Override
        protected Void doInBackground(Void... params) {
            // Create an array
            arraylist = new ArrayList<HashMap<String, String>>();
            // Retrieve JSON Objects from the given URL address
            jsonobject = JSONfunctions
                    .getJSONfromURL("http://www.adaderana.mobi/apple/ipad.php?q=topcat&cat=36");

            try {
                // Locate the array name in JSON
                jsonarray = jsonobject.getJSONArray("TopNewsGivenCat");

                for (int i = 0; i < jsonarray.length(); i++) {
                    HashMap<String, String> map = new HashMap<String, String>();
                    jsonobject = jsonarray.getJSONObject(i);
                    // Retrive JSON Objects
                    map.put("title", jsonobject.getString("title"));
                    map.put("author", jsonobject.getString("author"));
                    map.put("thumbnail", jsonobject.getString("thumbnail"));
                    map.put("contents", jsonobject.getString("contents"));
                    map.put("image", jsonobject.getString("image"));

                    // Set the JSON Objects into the array
                    arraylist.add(map);
                }
            } catch (JSONException e) {
                Log.e("Error", e.getMessage());
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void args) {
            // Locate the listview in listview_main.xml
            listview = (ListView) findViewById(R.id.listview);
            // Pass the results into ListViewAdapter.java
            adapter = new ListViewAdapter(MainActivity.this, arraylist);
            // Set the adapter to the ListView
            listview.setAdapter(adapter);
            // Close the progressdialog
            mProgressDialog.dismiss();
        }
    }
}

日志猫的最后一部分

07-21 03:58:03.110: I/Choreographer(1383): Skipped 31 frames!  The application may be doing too much work on its main thread.
07-21 03:58:04.110: I/MemoryCache(1383): MemoryCache will use up to 8.0MB
07-21 03:58:04.180: D/AndroidRuntime(1383): Shutting down VM
07-21 03:58:04.180: W/dalvikvm(1383): threadid=1: thread exiting with uncaught exception (group=0xb3a47b90)
07-21 03:58:04.200: E/AndroidRuntime(1383): FATAL EXCEPTION: main
07-21 03:58:04.200: E/AndroidRuntime(1383): Process: com.example.adaderana, PID: 1383
07-21 03:58:04.200: E/AndroidRuntime(1383): java.lang.NullPointerException
07-21 03:58:04.200: E/AndroidRuntime(1383):     at com.example.adaderana.MainActivity$DownloadJSON.onPostExecute(MainActivity.java:141)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at com.example.adaderana.MainActivity$DownloadJSON.onPostExecute(MainActivity.java:1)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at android.os.AsyncTask.finish(AsyncTask.java:632)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at android.os.AsyncTask.access$600(AsyncTask.java:177)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at android.os.Handler.dispatchMessage(Handler.java:102)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at android.os.Looper.loop(Looper.java:137)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at android.app.ActivityThread.main(ActivityThread.java:4998)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at java.lang.reflect.Method.invokeNative(Native Method)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at java.lang.reflect.Method.invoke(Method.java:515)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
07-21 03:58:04.200: E/AndroidRuntime(1383):     at dalvik.system.NativeStart.main(Native Method)
07-21 03:58:04.230: W/ActivityManager(371):   Force finishing activity com.example.adaderana/.MainActivity
07-21 03:58:04.270: D/gralloc(51): Registering a buffer in the process that created it. This may cause memory ordering problems.
07-21 03:58:04.270: E/libEGL(51): called unimplemented OpenGL ES API
07-21 03:58:04.280: E/libEGL(51): called unimplemented OpenGL ES API
07-21 03:58:04.280: E/libEGL(51): called unimplemented OpenGL ES API
07-21 03:58:04.280: E/libEGL(51): called unimplemented OpenGL ES API
07-21 03:58:04.280: E/SurfaceFlinger(51): glCheckFramebufferStatusOES error 1717000432
07-21 03:58:04.280: E/SurfaceFlinger(51): got GL_FRAMEBUFFER_COMPLETE_OES error while taking screenshot
07-21 03:58:04.280: E/libEGL(51): called unimplemented OpenGL ES API
07-21 03:58:04.280: E/libEGL(51): called unimplemented OpenGL ES API
07-21 03:58:04.290: W/WindowManager(371): Screenshot failure taking screenshot for (246x410) to layer 21015
07-21 03:58:04.590: I/Choreographer(371): Skipped 44 frames!  The application may be doing too much work on its main thread.
07-21 03:58:04.960: W/ActivityManager(371): Activity pause timeout for ActivityRecord{b3fc7818 u0 com.example.adaderana/.MainActivity t8 f}
07-21 03:58:04.980: I/Choreographer(371): Skipped 39 frames!  The application may be doing too much work on its main thread.
07-21 03:58:05.310: I/Choreographer(371): Skipped 36 frames!  The application may be doing too much work on its main thread.
07-21 03:58:05.450: I/Choreographer(371): Skipped 35 frames!  The application may be doing too much work on its main thread.
07-21 03:58:05.620: I/Choreographer(371): Skipped 169 frames!  The application may be doing too much work on its main thread.
07-21 03:58:08.450: I/Choreographer(371): Skipped 40 frames!  The application may be doing too much work on its main thread.
07-21 03:58:08.790: I/Choreographer(371): Skipped 34 frames!  The application may be doing too much work on its main thread.
07-21 03:58:08.930: I/Choreographer(371): Skipped 36 frames!  The application may be doing too much work on its main thread.
07-21 03:58:09.060: I/Choreographer(371): Skipped 31 frames!  The application may be doing too much work on its main thread.
07-21 03:58:19.250: W/ActivityManager(371): Activity destroy timeout for ActivityRecord{b3fc7818 u0 com.example.adaderana/.MainActivity t8 f}

最佳答案

您只在那里将new DownloadJSON().execute();放在“新闻”按钮onClick()中，如下所示:

Button b = (Button) findViewById(R.id.button1);

b.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        new DownloadJSON().execute();
    }
});

关于java - 开始时带有按钮的布局，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24857795/

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Answer 1

您只在那里将new DownloadJSON().execute();放在“新闻”按钮onClick()中，如下所示:

Button b = (Button) findViewById(R.id.button1);

b.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        new DownloadJSON().execute();
    }
});