Question

我在onPostExecute中使用以下代码。

我更新了代码

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.graphics.Color;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;
import android.widget.Toast;

public class LogStatus extends Activity {
    TableLayout tlLogStatus;

    // url to make request
    private static String url = "http://api.androidhive.info/contacts/";

            // JSON Node names
    private static final String TAG_LOGDETAILS = "contacts";
    private static final String TAG_DATE = "name";
    private static final String TAG_PERC = "id";

    // contacts JSONArray
    JSONArray jaLog = null;

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

        TableLayout tlLogStatus = (TableLayout) findViewById(R.id.main_table);

        TableRow tr_head = new TableRow(this);
        tr_head.setId(10);
        tr_head.setBackgroundColor(Color.RED);
        tr_head.setLayoutParams(new LayoutParams(
        LayoutParams.FILL_PARENT,
        LayoutParams.WRAP_CONTENT));

        TextView label_date = new TextView(this);
        label_date.setId(20);
        label_date.setText("Date");
        label_date.setTextColor(Color.WHITE);
        label_date.setPadding(5, 5, 5, 5);
        tr_head.addView(label_date);// add the column to the table row here

        TextView label_perc = new TextView(this);
        label_perc.setId(21);// define id that must be unique
        label_perc.setText("Percentage"); // set the text for the header 
        label_perc.setTextColor(Color.WHITE); // set the color
        label_perc.setPadding(5, 5, 5, 5); // set the padding (if required)
        tr_head.addView(label_perc); // add the column to the table row here

        tlLogStatus.addView(tr_head, new TableLayout.LayoutParams(
                LayoutParams.FILL_PARENT,
                LayoutParams.WRAP_CONTENT));

        new MyAsyncTask().execute(url);

    }   

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


    private class MyAsyncTask extends AsyncTask<String, Integer, JSONObject>{

        @Override
        protected JSONObject doInBackground(String... params) {
            // TODO Auto-generated method stub
            // Creating JSON Parser instance
            JSONParser jParser = new JSONParser();

            // getting JSON string from URL
            JSONObject json = jParser.getJSONFromUrl(params[0]);

            return json;
        }

        protected void onPostExecute(JSONObject json){
            //pb.setVisibility(View.GONE);
            try {
                // Getting Array of Contacts
                jaLog = json.getJSONArray(TAG_LOGDETAILS);
                TableLayout tlLogStatus = (TableLayout) findViewById(R.id.main_table);

                Integer count=0;
                // looping through All Contacts
                for(int i = 0; i < jaLog.length(); i++){
                    JSONObject c = jaLog.getJSONObject(i);

                    // Storing each json item in variable
                    String date = c.getString(TAG_DATE);
                    String perc = c.getString(TAG_PERC);

                    // Create the table row
                    TableRow tr = new TableRow(LogStatus.this);
                    if(count%2!=0) tr.setBackgroundColor(Color.GRAY);
                    if(count%2==0) tr.setBackgroundColor(Color.BLACK);
                    tr.setId(100+count);
                    tr.setLayoutParams(new LayoutParams(
                    LayoutParams.FILL_PARENT,
                    LayoutParams.WRAP_CONTENT));

                    //Create two columns to add as table data
                     // Create a TextView to add date
                    TextView labelDATE = new TextView(LogStatus.this);
                    labelDATE.setId(200+count); 
                    labelDATE.setText(date);
                    labelDATE.setPadding(2, 0, 5, 0);
                    labelDATE.setTextColor(Color.WHITE);
                    tr.addView(labelDATE);
                    TextView labelWEIGHT = new TextView(LogStatus.this);
                    labelWEIGHT.setId(200+count);
                    labelWEIGHT.setText(perc);
                    labelWEIGHT.setTextColor(Color.WHITE);
                    tr.addView(labelWEIGHT);

                    // finally add this to the table row
                    tlLogStatus.addView(tr, new TableLayout.LayoutParams(
                                            LayoutParams.FILL_PARENT,
                                            LayoutParams.WRAP_CONTENT));

                    count++;


                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }       
            Toast.makeText(getApplicationContext(), "command sent", Toast.LENGTH_LONG).show();
        }
        protected void onProgressUpdate(Integer... progress){
            //pb.setProgress(progress[0]);
        }


    }
}

我在这里遇到问题：

tlLogStatus.addView(tr_head, new TableLayout.LayoutParams(
                LayoutParams.FILL_PARENT,
                LayoutParams.WRAP_CONTENT));

我不知道如何解决这个问题。请帮忙

谢谢..

Answer 1

在变量名前onCreate()删除TableLayout，否则将其声明为局部变量，并且您的类'field tlLogStatus保持为空。

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_log_status);

        // no TableLayout before variable name!
        tlLogStatus = (TableLayout) findViewById(R.id.main_table);

        TableRow tr_head = new TableRow(this);
        ...
}

在onPostExecute()之后，您根本不需要这一行：

TableLayout tlLogStatus = (TableLayout) findViewById(R.id.main_table);

它只会使用父类中的tlLogStatus（您在onCreate()中设置的类），因此可以安全地删除此行。

在AsyncTask中将表行动态添加到Tablayout的问题

1 个答案: