java - Change/Update JTable content with JComboBox(category) -

i have problem jtable. jtable displays content of database. 1 database table has name category. every category displayed in jcombobox. if click on category should update table content.

here short snipped of code you, easier me. code should runable:

(testclass - main)

package test;  import java.awt.borderlayout; import java.awt.gridlayout; import java.awt.event.actionevent; import java.awt.event.actionlistener; import java.util.linkedlist;  import javax.swing.jcombobox; import javax.swing.jframe; import javax.swing.jpanel; import javax.swing.jscrollpane; import javax.swing.jtable;  public class testclass implements actionlistener{      string[] header = {"head", "head", "head"};     object[][] data = {{boolean.false, "text", "text"}, {boolean.false, "text", "text"}, {boolean.false, "text", "text"}};      linkedlist<string> newdata = new linkedlist<string>();      string[] combolist = {"apple", "banana", "cranberry"};      jcombobox<string> combobox = new jcombobox<string>(combolist);     jtable table = new jtable(new testtablemodel(data, header));     jframe frame = new jframe();     jpanel panel = new jpanel(new gridlayout(1, 0, 1, 0));      public testclass() {         combobox.addactionlistener(this);         panel.add(combobox);          frame.add(panel, borderlayout.north);         frame.add(new jscrollpane(table), borderlayout.center);          frame.setdefaultcloseoperation(jframe.exit_on_close);         frame.setlocationbyplatform(true);         frame.setvisible(true);         frame.pack();     }      @override     public void actionperformed(actionevent e) {         if (e.getsource() == this.combobox) {             jcombobox<string> combobox = this.combobox;              newdata.add("test1");             newdata.add("test2");              testtablemodel model = (testtablemodel) table.getmodel();              int = 0;             (string text : newdata) {                 data[i][0] = boolean.true;                 data[i][1] = text;                 data[i][2] = text;                 i++;             }              model.setdata(data);         }     }      public static void main(string[] args) {         new testclass();     } } 

(testtablemodel - abstracttablemodel if required (you need execute code!))

package test;  import javax.swing.table.abstracttablemodel;  public class testtablemodel extends abstracttablemodel {     private static final long serialversionuid = 5044877015250409328l;      private string[] header;     private object[][] data;      public testtablemodel(object[][] data, string[] header) {         this.header = header;         this.data = data;     }      public void setdata(object[][] data) {         this.data = data;         firetabledatachanged();     }      @override     public class<?> getcolumnclass(int column) {         if (column == 0) {             return boolean.class;         }         return super.getcolumnclass(column);     }      @override     public int getcolumncount() {         return header.length;     }      @override     public string getcolumnname(int column) {         return header[column];     }      @override     public int getrowcount() {         return data.length;     }      @override     public object getvalueat(int row, int column) {         return data[row][column];     }      @override     public boolean iscelleditable(int row, int column) {         return column == 0;     }      @override     public void setvalueat(object value, int row, int column) {         data[row][column] = value;     }  } 

with short code table freeze if change category. @ whole code,t freeze too, able see updated table in background when resize window (table resize same size frame). don't know why isn't @ snipped.

edit: problem change content has been solved. source has been updated. problem right table size hasent been solved yet. in source first use 3 row array , after 2 row array. want delete old table , create new one, row size right.

basically want update table new content.

• thank help!

the code buggy because every time actionperformed() called, creating new component:

table = new jtable(new testtablemodel(data, header)); frame.add(new jscrollpane( table ));  // <-- btw: here need put table otherwise adding empty jscrollpane frame.validate(); 

(note: there additional bug, @mkorbel mentioned it).

however have added jscrollpane jtable frame , continue exist. (if try resize window see new table beneath old one).

the correct way update table data tablemodel make modifications required in model , depending on changed fire apporpriate firexxx() method notify table redraw itself.

as crude example code be:

@override public void actionperformed(actionevent e) {     if (e.getsource() == this.combobox) {         jcombobox<string> combobox = this.combobox;          newdata.clear();    // clear list or create new 1 otherwise data keep piling up.           newdata.add("test1");         newdata.add("test2");          testtablemodel model = (testtablemodel) table.getmodel();          // since need replace whole data create new object[][] each time         object[][] newmodeldata = new object[newdata.size()][3];          // set whatever data new array         int = 0;         (string text : newdata) {             newmodeldata[i][0] = boolean.true;             newmodeldata[i][1] = text;             newmodeldata[i][2] = text;             i++;         }          // replace data of current model         model.setdata(newmodeldata);     } } ....  // inside table model:     ...     @override     public class<?> getcolumnclass(int column) {     // if (column == 0) {        //     return boolean.class;             // <-- produces classcastexception data aretrying set     // }        return super.getcolumnclass(column);     }      public void setdata(object[][] data) {         this.data = data;       //  <-- update data         firetabledatachanged(); //  <-- fire event table notified. if change 1 cell need call appropriate fire event     }     ... 

update 1: problem new code has fixed way update data in model. have logical flaw when update data structure. variable starts array of 3 rows. in actionperformed() method perform loop length of newdata list has 2 entries. update first 2 rows of model.

update 2: seems missing point. how update model matters here. table display whatever data model has. if update 2 rows leave 3rd 1 unmodified table display 3 rows (2 new ones , old one). since need change each time data need completely replace data in model. data need re-created each time not table. see update code example. have added actionperformed() method re-initializes data current source code. please read inline comments.