本文實例講述了java swing實現(xiàn)jtable檢測單元格數(shù)據(jù)變更事件的方法。分享給大家供大家參考，具體如下：
在jtable的初級教程中往往會提到，使用tablemodel的 addtablemodellistener方法可以監(jiān)聽單元格數(shù)據(jù)的變更，在其事件處理函，數(shù)tablechanged中，可以通過e.getcolumn()，e.getfirstrow()，e.getlastrow()，e.gettype()來獲取變更發(fā)生的位置和變更的類型（插入、更新或刪除）。然而該方法存在2個致命的問題：
1.雙擊單元格使其處于可編輯狀態(tài)后，即使沒有做出任何修改，當單元格失去焦點時，該事件將被激活。
2.通過該事件你可以獲取單元格最新的數(shù)據(jù)，卻無法獲取原有數(shù)據(jù)。
經(jīng)過一番搜索發(fā)現(xiàn)該文章已經(jīng)解決了這個問題table cell listener，作者自己實現(xiàn)了一個單元格監(jiān)聽器tablecelllistener，它訂閱了指定table的addpropertychangelistener，根據(jù)e.getpropertyname()來識別單元格編輯事件，根據(jù)table.isediting()方法來判斷單元格正在編輯還是編輯完畢。如果是正在編輯，則記錄單元格位置和原因數(shù)據(jù)；如果已經(jīng)編輯完畢，則記錄新數(shù)據(jù)并與原有數(shù)據(jù)進行比對，如果不一致則說明單元格數(shù)據(jù)發(fā)生了變更，則激活指定響應函數(shù)。
測試用例如下：
tabledemo.java
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/* * copyright (c) 1995, 2008, oracle and/or its affiliates. all rights reserved. * * redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - neither the name of oracle or the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * this software is provided by the copyright holders and contributors "as * is" and any express or implied warranties, including, but not limited to, * the implied warranties of merchantability and fitness for a particular * purpose are disclaimed. in no event shall the copyright owner or * contributors be liable for any direct, indirect, incidental, special, * exemplary, or consequential damages (including, but not limited to, * procurement of substitute goods or services; loss of use, data, or * profits; or business interruption) however caused and on any theory of * liability, whether in contract, strict liability, or tort (including * negligence or otherwise) arising in any way out of the use of this * software, even if advised of the possibility of such damage. */package awtdemo;/* * tabledemo.java requires no other files. */import javax.swing.abstractaction;import javax.swing.action;import javax.swing.jframe;import javax.swing.jpanel;import javax.swing.jscrollpane;import javax.swing.jtable;import javax.swing.table.abstracttablemodel;import java.awt.dimension;import java.awt.gridlayout;import java.awt.event.actionevent;/** * tabledemo is just like simpletabledemo, except that it * uses a custom tablemodel. */@suppresswarnings("serial")public class tabledemo extends jpanel { private boolean debug = false; @suppresswarnings("unused") public tabledemo() { super(new gridlayout(1,0)); jtable table = new jtable(new mytablemodel()); table.setpreferredscrollableviewportsize(new dimension(500, 70)); table.setfillsviewportheight(true); //create the scroll pane and add the table to it. jscrollpane scrollpane = new jscrollpane(table); //add the scroll pane to this panel. add(scrollpane); action action = new abstractaction() { public void actionperformed(actionevent e) { tablecelllistener tcl = (tablecelllistener)e.getsource(); system.out.printf("cell changed%n"); system.out.println("row : " + tcl.getrow()); system.out.println("column: " + tcl.getcolumn()); system.out.println("old : " + tcl.getoldvalue()); system.out.println("new : " + tcl.getnewvalue()); } }; tablecelllistener tcl = new tablecelllistener(table, action); } class mytablemodel extends abstracttablemodel { private string[] columnnames = {"first name", "last name", "sport", "# of years", "vegetarian"}; private object[][] data = { {"kathy", "smith", "snowboarding", new integer(5), new boolean(false)}, {"john", "doe", "rowing", new integer(3), new boolean(true)}, {"sue", "black", "knitting", new integer(2), new boolean(false)}, {"jane", "white", "speed reading", new integer(20), new boolean(true)}, {"joe", "brown", "pool", new integer(10), new boolean(false)} }; public int getcolumncount() { return columnnames.length; } public int getrowcount() { return data.length; } public string getcolumnname(int col) { return columnnames[col]; } public object getvalueat(int row, int col) { return data[row][col]; } /* * jtable uses this method to determine the default renderer/ * editor for each cell. if we didn't implement this method, * then the last column would contain text ("true"/"false"), * rather than a check box. */ @suppresswarnings({ "unchecked", "rawtypes" }) public class getcolumnclass(int c) { return getvalueat(0, c).getclass(); } /* * don't need to implement this method unless your table's * editable. */ public boolean iscelleditable(int row, int col) { //note that the data/cell address is constant, //no matter where the cell appears onscreen. if (col < 2) { return false; } else { return true; } } /* * don't need to implement this method unless your table's * data can change. */ public void setvalueat(object value, int row, int col) { if (debug) { system.out.println("setting value at " + row + "," + col + " to " + value + " (an instance of " + value.getclass() + ")"); } data[row][col] = value; firetablecellupdated(row, col); if (debug) { system.out.println("new value of data:"); printdebugdata(); } } private void printdebugdata() { int numrows = getrowcount(); int numcols = getcolumncount(); for (int i=0; i < numrows; i++) { system.out.print(" row " + i + ":"); for (int j=0; j < numcols; j++) { system.out.print(" " + data[i][j]); } system.out.println(); } system.out.println("--------------------------"); } } /** * create the gui and show it. for thread safety, * this method should be invoked from the * event-dispatching thread. */ private static void createandshowgui() { //create and set up the window. jframe frame = new jframe("tabledemo - www.ythuaji.com.cn"); frame.setdefaultcloseoperation(jframe.exit_on_close); //create and set up the content pane. tabledemo newcontentpane = new tabledemo(); newcontentpane.setopaque(true); //content panes must be opaque frame.setcontentpane(newcontentpane); //display the window. frame.pack(); frame.setvisible(true); } public static void main(string[] args) { //schedule a job for the event-dispatching thread: //creating and showing this application's gui. javax.swing.swingutilities.invokelater(new runnable() { public void run() { createandshowgui(); } }); }} |
tablecelllistener.java
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package awtdemo;import java.awt.event.*;import javax.swing.*;import java.beans.*;/* * this class listens for changes made to the data in the table via the * tablecelleditor. when editing is started, the value of the cell is saved * when editing is stopped the new value is saved. when the oold and new * values are different, then the provided action is invoked. * * the source of the action is a tablecelllistener instance. */public class tablecelllistener implements propertychangelistener, runnable{ private jtable table; private action action; private int row; private int column; private object oldvalue; private object newvalue; /** * create a tablecelllistener. * * @param table the table to be monitored for data changes * @param action the action to invoke when cell data is changed */ public tablecelllistener(jtable table, action action) { this.table = table; this.action = action; this.table.addpropertychangelistener( this ); } /** * create a tablecelllistener with a copy of all the data relevant to * the change of data for a given cell. * * @param row the row of the changed cell * @param column the column of the changed cell * @param oldvalue the old data of the changed cell * @param newvalue the new data of the changed cell */ private tablecelllistener(jtable table, int row, int column, object oldvalue, object newvalue) { this.table = table; this.row = row; this.column = column; this.oldvalue = oldvalue; this.newvalue = newvalue; } /** * get the column that was last edited * * @return the column that was edited */ public int getcolumn() { return column; } /** * get the new value in the cell * * @return the new value in the cell */ public object getnewvalue() { return newvalue; } /** * get the old value of the cell * * @return the old value of the cell */ public object getoldvalue() { return oldvalue; } /** * get the row that was last edited * * @return the row that was edited */ public int getrow() { return row; } /** * get the table of the cell that was changed * * @return the table of the cell that was changed */ public jtable gettable() { return table; }//// implement the propertychangelistener interface// @override public void propertychange(propertychangeevent e) { // a cell has started/stopped editing if ("tablecelleditor".equals(e.getpropertyname())) { if (table.isediting()){ //system.out.printf("tablecelleditor is editing..%n"); processeditingstarted(); } else{ //system.out.printf("tablecelleditor editing stopped..%n"); processeditingstopped(); } } } /* * save information of the cell about to be edited */ private void processeditingstarted() { // the invokelater is necessary because the editing row and editing // column of the table have not been set when the "tablecelleditor" // propertychangeevent is fired. // this results in the "run" method being invoked swingutilities.invokelater( this ); } /* * see above. */ @override public void run() { row = table.convertrowindextomodel( table.geteditingrow() ); column = table.convertcolumnindextomodel( table.geteditingcolumn() ); oldvalue = table.getmodel().getvalueat(row, column); //這里應對oldvalue為null的情況做處理，否則將導致原值與新值均為空時仍被視為值改變 if(oldvalue == null) oldvalue = ""; newvalue = null; } /* * update the cell history when necessary */ private void processeditingstopped() { newvalue = table.getmodel().getvalueat(row, column); //這里應對newvalue為null的情況做處理，否則后面會拋出異常 if(newvalue == null) newvalue = ""; // the data has changed, invoke the supplied action if (! newvalue.equals(oldvalue)) { // make a copy of the data in case another cell starts editing // while processing this change tablecelllistener tcl = new tablecelllistener( gettable(), getrow(), getcolumn(), getoldvalue(), getnewvalue()); actionevent event = new actionevent( tcl, actionevent.action_performed, ""); action.actionperformed(event); } }} |
運行效果：
由圖可見，單元格數(shù)據(jù)修改后，控制臺輸出內(nèi)容變更信息！
希望本文所述對大家java程序設計有所幫助。
原文鏈接：http://www.cnblogs.com/pzy4447/p/5164775.html
