Android GUI不显示

Question

I am currently making an app for android and I have a problem where the UI on a new activity that I start from the main one does not show up. I have no idea what the problem is.

Here is my second activity's layout xml file:

<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/TableLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.tabcards.android.Search" >

<TableRow
    android:id="@+id/tableRow1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1" >

    <ScrollView
        android:id="@+id/scrollView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="5dp"
         >

        <TableLayout
            android:id="@+id/tableScrollView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:stretchColumns="yes"
            android:padding="5dp" 
            android:background="@color/gray">
        </TableLayout>
    </ScrollView>
</TableRow>

Here is my acitiviy's code:

public class Search extends ActionBarActivity {
TableLayout tableScrollView;
String[] JSONExceptions = { "type", "em", "user_id", "id", "profilepic", "bg"};
String value;
JSONObject jObject;

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

    Bundle extras = getIntent().getExtras();
    if (extras != null) {
        value = extras.getString("id");
    }
    System.out.println(value);
    tableScrollView = (TableLayout) findViewById(R.id.tableScrollView);
    Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {
            try {

                jObject = getJson("http://www.tabcards.com/req/androidapi/L2o30H8JlFMtFYHW3KLxkts20ztc5Be6Z6m6v315/json/"
                            + value);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
    thread.start();
    try {
        thread.join();
    } catch (InterruptedException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
    new Thread(new Runnable() {

        @Override
        public void run() {
            try {
                createUI(jObject);
            } catch (JSONException e) {
                e.printStackTrace();
            }               
        }

    });

    System.out.println("complete");

}

private void createUI(JSONObject jObject) throws JSONException {

    Iterator<?> keys = jObject.keys();
    int absIndex = 0;
    while( keys.hasNext() ){
        String key = (String)keys.next();
        if(!contains2(JSONExceptions , jObject.get(key))){
            String value = jObject.getString(key);
            System.out.println("level 1");
            if(value!="") {
                insertElement(key + " : " + value, absIndex++);

            }
        }
    }
}

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

private void insertElement(String data, int i) {
    LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View newRow = inflater.inflate(R.layout.row, null, false);
    newRow.setLayoutParams(new TableRow.LayoutParams(TableRow.LayoutParams.MATCH_PARENT, TableRow.LayoutParams.WRAP_CONTENT));

    TextView dataTextView = (TextView) newRow
            .findViewById(R.id.rowTextView);
    dataTextView.setText(data);
    System.out.println(dataTextView.getText().toString());
    tableScrollView.addView(newRow, i);

}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}

private InputStream downloadUrl(String urlString) throws IOException {
    URL url = new URL(urlString);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setReadTimeout(10000 /* milliseconds */);
    conn.setConnectTimeout(15000 /* milliseconds */);
    conn.setRequestMethod("GET");
    conn.setDoInput(true);
    // Starts the query
    conn.connect();
    return conn.getInputStream();
}

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

public static JSONObject getJson(String url){

    InputStream is = null;
    String result = "";
    JSONObject jsonObject = null;

    // HTTP
    try {           
        HttpClient httpclient = new DefaultHttpClient(); // for port 80 requests!
        HttpPost httppost = new HttpPost(url);
        HttpResponse response = httpclient.execute(httppost);
        HttpEntity entity = response.getEntity();
        is = entity.getContent();
    } catch(Exception e) {
        return null;
    }

    // Read response to string
    try {           
        BufferedReader reader = new BufferedReader(new InputStreamReader(is,"utf-8"),8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
            System.out.println(line);
        }
        is.close();
        result = sb.toString().replace("[", "");                
    } catch(Exception e) {
        return null;
    }

    // Convert string to object
    try {
        jsonObject = new JSONObject(result.replace("]", ""));            
    } catch(JSONException e) {
        return null;
    }

    return jsonObject;

}

This is how I am creating the activity:

Intent i = new Intent(getApplicationContext(), Search.class);
i.putExtra("id",searchEditText.getText().toString());
startActivity(i);

Tell me if you need any more info.

Answer 1

problem:

thread.join();

That problem is dreadlock you are waiting for thread to be done executing, which will put your UI thread to the Blocking state like Thread.Sleep() thus UI thread is waiting for your request to be done executing before it can display the layout in the screen.

from documentation :

Like sleep, join responds to an interrupt by exiting with an InterruptedException.

solution:

Use only one thread which will still wait for the request( createUI ) and executes your createUI method after.

Thread thread = new Thread(new Runnable() {
    @Override
    public void run() {
        try {

            jObject = getJson("http://www.tabcards.com/req/androidapi/L2o30H8JlFMtFYHW3KLxkts20ztc5Be6Z6m6v315/json/"
                        + value);
            createUI(jObject);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
});
thread.start();