TableLayout - The specified child already has a parent

Question

I am trying to create a simple table programmatically. But the code crashes when row2.addView is called. With this error:

Caused by: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.

Here is my code:

import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.contnt_2);

        TableLayout tableLayout = new TableLayout(this);

        TableRow.LayoutParams tableRowParams = new TableRow.LayoutParams();
        tableRowParams.setMargins(1, 1, 1, 1);


        TableRow row1 = new TableRow(this);
        TableRow row2 = new TableRow(this);
        TableRow row3 = new TableRow(this);

        TextView text1 = new TextView(this);
        text1.setText("DDDDDDDDDDDDD");
        text1.setBackgroundColor(Color.GRAY);

        TextView text2 = new TextView(this);
        text2.setText("DDDDDDDDDDDDD");
        text2.setBackgroundColor(Color.GRAY);

        TextView text3 = new TextView(this);
        text3.setText("DDDDDDDDDDDDD");
        text3.setBackgroundColor(Color.GRAY);

        row1.addView(text1, tableRowParams);
        row1.addView(text2, tableRowParams);
        row1.addView(text3, tableRowParams);

        row2.addView(text1, tableRowParams);
        row2.addView(text2, tableRowParams);
        row2.addView(text3, tableRowParams);

        row3.addView(text1, tableRowParams);
        row3.addView(text2, tableRowParams);
        row3.addView(text3, tableRowParams);

        tableLayout.addView(row1);
        tableLayout.addView(row2);
        tableLayout.addView(row3);

        setContentView(tableLayout);

    }

I can't find a reason why it happens. how correctly to add rows to table ? Can you help me out?

Answer 1

This is because you created three TextViews and added them to your first TableRow with this code:

row1.addView(text1, tableRowParams);
row1.addView(text2, tableRowParams);
row1.addView(text3, tableRowParams);

Then tried adding that same TextView that you already created to Row 2.

You can't add the same TextView to multiple TableRows, because as the error says, each TextView can only have one parent.

You need to create three different TextViews for EACH TableRow.

Answer 2

The main problem with your approach: A view can't be a child of more than one parent in Android.

Here's a tutorial on how to create a TableLayout programmatically, maybe you get some ideas for improvements to your logic: http://www.prandroid.com/2014/05/creating-table-layout-dynamically-in.html

I'll paste it here as well just in case:

public class MainActivity extends Activity {


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

     String[] row = { "ROW1", "ROW2", "Row3", "Row4", "Row 5", "Row 6",
  "Row 7" };
        String[] column = { "COLUMN1", "COLUMN2", "COLUMN3", "COLUMN4",
  "COLUMN5", "COLUMN6" };
    int rl=row.length; int cl=column.length;

     Log.d("--", "R-Lenght--"+rl+"   "+"C-Lenght--"+cl);

  ScrollView sv = new ScrollView(this);
     TableLayout tableLayout = createTableLayout(row, column,rl, cl);
     HorizontalScrollView hsv = new HorizontalScrollView(this);

     hsv.addView(tableLayout);
  sv.addView(hsv);
  setContentView(sv);

 }

 public void makeCellEmpty(TableLayout tableLayout, int rowIndex, int columnIndex) {
     // get row from table with rowIndex
     TableRow tableRow = (TableRow) tableLayout.getChildAt(rowIndex);

     // get cell from row with columnIndex
     TextView textView = (TextView)tableRow.getChildAt(columnIndex);

     // make it black
     textView.setBackgroundColor(Color.BLACK);
 }
 public void setHeaderTitle(TableLayout tableLayout, int rowIndex, int columnIndex){

     // get row from table with rowIndex
     TableRow tableRow = (TableRow) tableLayout.getChildAt(rowIndex);

     // get cell from row with columnIndex
     TextView textView = (TextView)tableRow.getChildAt(columnIndex);

     textView.setText("Hello");
 }

 private TableLayout createTableLayout(String [] rv, String [] cv,int rowCount, int columnCount) {
     // 1) Create a tableLayout and its params
     TableLayout.LayoutParams tableLayoutParams = new TableLayout.LayoutParams();
     TableLayout tableLayout = new TableLayout(this);
     tableLayout.setBackgroundColor(Color.BLACK);

     // 2) create tableRow params
     TableRow.LayoutParams tableRowParams = new TableRow.LayoutParams();
     tableRowParams.setMargins(1, 1, 1, 1);
     tableRowParams.weight = 1;

     for (int i = 0; i < rowCount; i++) {
         // 3) create tableRow
         TableRow tableRow = new TableRow(this);
         tableRow.setBackgroundColor(Color.BLACK);

         for (int j= 0; j < columnCount; j++) {
             // 4) create textView
             TextView textView = new TextView(this);
           //  textView.setText(String.valueOf(j));
             textView.setBackgroundColor(Color.WHITE);
             textView.setGravity(Gravity.CENTER);

             String s1 = Integer.toString(i);
    String s2 = Integer.toString(j);
    String s3 = s1 + s2;
    int id = Integer.parseInt(s3);
    Log.d("TAG", "-___>"+id);
              if (i ==0 && j==0){
               textView.setText("0==0");
              } else if(i==0){
               Log.d("TAAG", "set Column Headers");
              textView.setText(cv[j-1]);
              }else if( j==0){
               Log.d("TAAG", "Set Row Headers");
               textView.setText(rv[i-1]);
              }else {
              textView.setText(""+id);
              // check id=23
              if(id==23){
                textView.setText("ID=23");

               }
              }

             // 5) add textView to tableRow
             tableRow.addView(textView, tableRowParams);
         }

         // 6) add tableRow to tableLayout
         tableLayout.addView(tableRow, tableLayoutParams);
     }

     return tableLayout;
 }
 }