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我使用以下代碼從mysql學生數據庫中檢索數據。它工作正常。它將在組合框中顯示學生名稱。值從Db中檢索。JCombobox值從我的Sql查詢
我的問題是自動顯示在Jcombobox名稱字段中的第一個值（存儲在數據庫列中的第一個學生名稱），當我單擊組合框箭頭時顯示它。這意味着當我執行下面的代碼時，第一個值（第一個名稱）在combobox的名稱字段附近的箭頭。但我需要在那裏的「學生名稱」標題。如果我分配了設計時間，但同樣的名字再次顯示時，我點擊箭頭。如何解決這個問題？
我的另一個問題是，如何讓選擇「組合框中的項目」當我輸入組合框的名字field.It意味着，如果我輸入S表示選中組合框中的項目相應地開始與S.
package designstudent;
import java.awt.*;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.*;
import javax.swing.table.DefaultTableModel;
import java.sql.*;
import javax.swing.JOptionPane;
import javax.swing.ListSelectionModel;
import javax.swing.*;
public class FrmeA extends javax.swing.JFrame {
FrmA1 f1=new FrmA1();
Statement TmpFlxTSt=null;
ResultSet TmpFlxTRs=null;
GContnStr GCS=new GContnStr();
public FrmeA() {
initComponents();
}
public void combo() {
try {
GCS.GContnStr();
TmpFlxTSt= GCS.GCotnStr.createStatement();
String select = "Select StudName from studentmaster";
TmpFlxTRs = TmpFlxTSt.executeQuery(select);
while (TmpFlxTRs.next()) {
cbx.addItem(TmpFlxTRs.getString("StudName"));
Object comboitem=cbx.getSelectedItem();
}
TmpFlxTRs.close();
TmpFlxTSt.close();
}
catch(Exception e) {
System.out.println(e);
}
}
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jPanel1 = new javax.swing.JPanel();
jPanel2 = new javax.swing.JPanel();
CmdA = new javax.swing.JButton();
CmdE = new javax.swing.JButton();
CmdD = new javax.swing.JButton();
cmdQ = new javax.swing.JButton();
jPanel3 = new javax.swing.JPanel();
jScrollPane1 = new javax.swing.JScrollPane();
FlxT = new javax.swing.JTable();
cbx = new javax.swing.JComboBox();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jPanel2.setBorder(
javax.swing.BorderFactory.createTitledBorder(
javax.swing.BorderFactory.createMatteBorder(
1, 1, 1, 1, new java.awt.Color(0, 0, 255
)
), "Commands")
);
CmdA.setFont(new java.awt.Font("Arial", 0, 10));
CmdA.setText("+");
CmdA.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
CmdAActionPerformed(evt);
}
});
CmdE.setFont(new java.awt.Font("Arial", 0, 10));
CmdE.setText("E");
CmdD.setFont(new java.awt.Font("Arial", 0, 10));
CmdD.setText("-");
cmdQ.setFont(new java.awt.Font("Arial", 0, 10));
cmdQ.setText("Q");
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(
javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addContainerGap()
.addComponent(
CmdA,javax.swing.GroupLayout.PREFERRED_SIZE,64,javax.swing.GroupLayout.PREFERRED_SIZE
)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(CmdE, javax.swing.GroupLayout.PREFERRED_SIZE, 75, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(CmdD, javax.swing.GroupLayout.DEFAULT_SIZE, 72, Short.MAX_VALUE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(cmdQ, javax.swing.GroupLayout.PREFERRED_SIZE, 72, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(35, 35, 35))
);
jPanel2Layout.linkSize(javax.swing.SwingConstants.HORIZONTAL, new java.awt.Component[] {CmdA, CmdE, cmdQ});
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel2Layout.createSequentialGroup()
.addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(CmdA, javax.swing.GroupLayout.PREFERRED_SIZE, 79, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(CmdE, javax.swing.GroupLayout.DEFAULT_SIZE, 79, Short.MAX_VALUE)
.addComponent(CmdD, javax.swing.GroupLayout.DEFAULT_SIZE, 79, Short.MAX_VALUE)
.addComponent(cmdQ, javax.swing.GroupLayout.DEFAULT_SIZE, 79, Short.MAX_VALUE))
.addContainerGap())
);
jPanel3.setBorder(javax.swing.BorderFactory.createMatteBorder(1, 1, 1, 1, new java.awt.Color(0, 0, 255)));
FlxT.setFont(new java.awt.Font("Arial", 0, 10));
FlxT.setModel(new javax.swing.table.DefaultTableModel(
new Object [][] {
},
new String [] {
"StudName", "StudClass", "StudMrk1", "StudMrk2", "StudTot", "StudRes", "StudNO", "StudId"
}
) {
Class[] types = new Class [] {
java.lang.String.class, java.lang.Integer.class, java.lang.Integer.class, java.lang.Integer.class, java.lang.Integer.class, java.lang.String.class, java.lang.Integer.class, java.lang.Integer.class
};
public Class getColumnClass(int columnIndex) {
return types [columnIndex];
}
});
jScrollPane1.setViewportView(FlxT);
FlxT.getColumnModel().getColumn(0).setResizable(false);
FlxT.getColumnModel().getColumn(0).setPreferredWidth(150);
FlxT.getColumnModel().getColumn(1).setResizable(false);
FlxT.getColumnModel().getColumn(1).setPreferredWidth(70);
FlxT.getColumnModel().getColumn(2).setResizable(false);
FlxT.getColumnModel().getColumn(2).setPreferredWidth(70);
FlxT.getColumnModel().getColumn(3).setResizable(false);
FlxT.getColumnModel().getColumn(3).setPreferredWidth(70);
FlxT.getColumnModel().getColumn(4).setResizable(false);
FlxT.getColumnModel().getColumn(4).setPreferredWidth(70);
FlxT.getColumnModel().getColumn(5).setResizable(false);
FlxT.getColumnModel().getColumn(5).setPreferredWidth(70);
FlxT.getColumnModel().getColumn(6).setMinWidth(0);
FlxT.getColumnModel().getColumn(6).setPreferredWidth(0);
FlxT.getColumnModel().getColumn(6).setMaxWidth(0);
FlxT.getColumnModel().getColumn(7).setMinWidth(0);
FlxT.getColumnModel().getColumn(7).setPreferredWidth(0);
FlxT.getColumnModel().getColumn(7).setMaxWidth(0);
javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 1015, Short.MAX_VALUE)
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel3Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 995, Short.MAX_VALUE)
.addContainerGap()))
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 249, Short.MAX_VALUE)
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel3Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 184, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(54, Short.MAX_VALUE)))
);
cbx.setEditable(true);
cbx.setFont(new java.awt.Font("Arial", 0, 10)); // NOI18N
cbx.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
cbxActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
.addContainerGap(657, Short.MAX_VALUE)
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(122, 122, 122)
.addComponent(cbx, javax.swing.GroupLayout.PREFERRED_SIZE, 124, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(791, Short.MAX_VALUE))
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addContainerGap()
.addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap()))
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(19, 19, 19)
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGap(18, 18, 18)
.addComponent(cbx, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(777, Short.MAX_VALUE))
.addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel1Layout.createSequentialGroup()
.addGap(190, 190, 190)
.addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(503, Short.MAX_VALUE)))
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 1047, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 955, Short.MAX_VALUE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
);
pack();
java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
java.awt.Dimension dialogSize = getSize();
setLocation((screenSize.width-dialogSize.width)/2,(screenSize.height-dialogSize.height)/2);
}// </editor-fold>
private void CmdAActionPerformed(java.awt.event.ActionEvent evt) {
f1.setVisible(true);
// TODO add your handling code here:
}
private void cbxActionPerformed(java.awt.event.ActionEvent evt) {
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
FrmeA fr=new FrmeA();
fr.combo();
fr.setVisible(true);
//fr.initconn();
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton CmdA;
private javax.swing.JButton CmdD;
private javax.swing.JButton CmdE;
private javax.swing.JTable FlxT;
private javax.swing.JComboBox cbx;
private javax.swing.JButton cmdQ;
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JPanel jPanel3;
private javax.swing.JScrollPane jScrollPane1;
// End of variables declaration
}
請把這個減到一個[SSCCE]（http://sscce.org/），證明您遇到的問題。 – 2012-01-02 07:50:17
問題還不清楚，「我的另一個問題」是不允許的是SO：如果你認爲這個問題是值得的，那麼打開另一個線程。 – dendini 2013-07-22 13:05:34