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访问另一个类java中的方法时出错

程序问答   发布时间：2022-06-02  发布网站：大佬教程  code.js-code.com
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如何解决访问另一个类java中的方法时出错？

开发过程中遇到访问另一个类java中的方法时出错的问题如何解决？下面主要结合日常开发的经验，给出你关于访问另一个类java中的方法时出错的解决方法建议，希望对你解决访问另一个类java中的方法时出错有所启发或帮助；

我有这样的错误

Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
at tugasakhir.Home.TambahActionPerformed(Home.java:285)
at tugasakhir.Home.access$300(Home.java:14)
at tugasakhir.Home$4.actionPerformed(Home.java:97)
at javax.swing.Abstractbutton.fireActionPerformed(Abstractbutton.java:2022)
at javax.swing.Abstractbutton$Handler.actionPerformed(Abstractbutton.java:2348)
at javax.swing.DefaultbuttonModel.fireActionPerformed(DefaultbuttonModel.java:402)
at javax.swing.DefaultbuttonModel.setpressed(DefaultbuttonModel.java:259)
at javax.swing.plaf.basic.basicbuttonListener.mouseReleased(BasicbuttonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6539)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6304)
at java.awt.Container.processEvent(Container.java:2239)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.lightweightdispatcher.retargetMouseEvent(Container.java:4904)
at java.awt.lightweightdispatcher.processMouseEvent(Container.java:4535)
at java.awt.lightweightdispatcher.dispatchEvent(Container.java:4476)
at java.awt.Container.dispatchEventImpl(Container.java:2283)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doprivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
at java.awt.EventQueue$4.run(EventQueue.java:733)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.security.AccessController.doprivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
at org.GNOME.Accessibility.AtkWrapper$6.dispatchEvent(AtkWrapper.java:715)
at java.awt.EventdispatchThread.pumpOneEventForFilters(EventdispatchThread.java:205)
at java.awt.EventdispatchThread.pumpEventsForFilter(EventdispatchThread.java:116)
at java.awt.EventdispatchThread.pumpEventsForHIErarchy(EventdispatchThread.java:105)
at java.awt.EventdispatchThread.pumpEvents(EventdispatchThread.java:101)
at java.awt.EventdispatchThread.pumpEvents(EventdispatchThread.java:93)
at java.awt.EventdispatchThread.run(EventdispatchThread.java:82)

这是我的代码

TugasAkhir.java

package tugasakhir;

public class TugasAkhir {

public static Home hm=new Home();
public static DataCore dt=new DataCore();

public static voID main(String[] args) {
    hm.setVisible@R_618_6334@;
    hm.pack();
    hm.setLOCATIOnrelativeTo(null);
    hm.setDefaultCloSEOperation(Home.EXIT_ON_CLOSE);
    
    dt.setVisible@R_618_6334@;
    dt.pack();
    dt.setLOCATIOnrelativeTo(null);
    dt.setDefaultCloSEOperation(DataCore.EXIT_ON_CLOSE);
    dt.setState(1);
  }
}

DataCore.java

    Home hm=TugasAkhir.hm;

    public int Searchtable(int j,String query){
        for (int k = 0; k < tables.getRowCount(); k++) {
            if(Pattern.matches(".*"+query+".*",(String)tables.getValueAt(k,j))){
                System.out.println("Row: "+k+",Col: "+j);
                return k;
            }
        }
        return 0;
    }
    
    public voID check(){
        System.out.print(tables.getValueAt(0,1));
    }
    
    public String GetValue(int j,int k){
        return (String)tables.getValueAt(j,k);
    }
    public int GeTint(int j,int k){
        return (Integer)tables.getValueAt(j,k);
    }
    
    public voID SETVALue(int value,int j,int k){
        tables.SETVALueAt(value,j,k);
    }
    
    public voID tambahini(String Nama,int jumlah){
        int harga = 121;
        javax.swing.table.DefaulttableModel model = (javax.swing.table.DefaulttableModel) hm.Tabl.getModel();
        model.addRow(new Object[]{Nama,harga,jumlah,harga * jumlah});
    }
    
  
    
    private voID TambahActionPerformed(java.awt.event.ActionEvent evt) {                                       
        javax.swing.table.DefaulttableModel model = (javax.swing.table.DefaulttableModel) tables.getModel();
        String nama = Nama.getText();
        Integer jumlah = Integer.valueOf(Jumlah.getText());
        Integer harga = Integer.valueOf(Harga.getText());
        model.addRow(new Object[]{nama,});
    }                                      

    private voID KembaliActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // Todo add your handling code here:
        Home hm = TugasAkhir.hm;
        hm.setState(0);
        this.setState(1);
    }                                       

    private voID HapusActionPerformed(java.awt.event.ActionEvent evt) {                                      
        // Todo add your handling code here:
        javax.swing.table.DefaulttableModel model = (javax.swing.table.DefaulttableModel) tables.getModel();
        model.removeRow(tables.get@R_801_10288@ctedRow());
    }                                                                  

    public static voID main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setTing code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available,stay with the default look and feel.
         * For details see http://download.Oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.HTML 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelinfo info : javax.swing.UIManager.geTinstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getname())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassname());
                    break;
                }
            }
        } catch (ClassnotFoundException eX) {
            java.util.logging.Logger.getLogger(DataCore.class.getname()).log(java.util.logging.Level.SEVERE,null,eX);
        } catch (InstantiationException eX) {
            java.util.logging.Logger.getLogger(DataCore.class.getname()).log(java.util.logging.Level.SEVERE,eX);
        } catch (illegalaccessexception eX) {
            java.util.logging.Logger.getLogger(DataCore.class.getname()).log(java.util.logging.Level.SEVERE,eX);
        } catch (javax.swing.UnsupportedLookAndFeelException eX) {
            java.util.logging.Logger.getLogger(DataCore.class.getname()).log(java.util.logging.Level.SEVERE,eX);
        }
        //</editor-fold>
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokelater(new Runnable() {
            public voID run() {
                new DataCore().setVisible@R_618_6334@;
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.Jbutton Hapus;
    private javax.swing.JTextFIEld Harga;
    private javax.swing.JTextFIEld Jumlah;
    private javax.swing.Jbutton Kembali;
    private javax.swing.JTextFIEld Nama;
    public javax.swing.Jtable tables;
    private javax.swing.Jbutton Tambah;
    private javax.swing.Jbutton Ubah;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel6;
    private javax.swing.JscrollPane JscrollPane1;
    // End of variables declaration                   
}

Home.java

/*
 * To change this license header,choose license headers in Project PropertIEs.
 * To change this template file,choose Tools | Templates
 * and open the template in the editor.
 */
package tugasakhir;

import java.util.regex.Pattern;
public class Home extends javax.swing.JFrame {
    DataCore dc = TugasAkhir.dt;

    public voID addItemsintable(String nama,int harga,int jumlah){
        javax.swing.table.DefaulttableModel model = (javax.swing.table.DefaulttableModel) this.Tabl.getModel();
        model.addRow(new Object[]{nama,harga * jumlah});
    }

    private voID TambahActionPerformed(java.awt.event.ActionEvent evt) {                                       
        // Todo add your handling code here
        
        //Inisialisasi Variable\
        String nama = Nama.getText();
        int jumlah = Integer.valueOf(Jumlah.getText());
        
        //Kirim data
        dc.tambahini(nama,jumlah);
        
    }                                      

    private voID BersihActionPerformed(java.awt.event.ActionEvent evt) {                                       
        // Todo add your handling code here:
        Nama.setText("");
        Jumlah.setText("");
        @R_228_10586@l.setText("");
        Bayar.setText("");
        
    }                                      

    private voID lihatActionPerformed(java.awt.event.ActionEvent evt) {                                      
        // Todo add your handling code here:
        DataCore dt = TugasAkhir.dt;
        dt.setState(0);
        this.setState(1);
        
    }                                     
    
    private voID OKActionPerformed(java.awt.event.ActionEvent evt) {                                   
        // Todo add your handling code here:
        dc.check();
    }                                  


    private voID HapusActionPerformed(java.awt.event.ActionEvent evt) {                                      
        // Todo add your handling code here:
        javax.swing.table.DefaulttableModel model = (javax.swing.table.DefaulttableModel) Tabl.getModel();
        model.removeRow(Tabl.get@R_801_10288@ctedRow());
    }                                     

    private voID JscrollPane1MouseClicked(java.awt.event.MouseEvent evt) {                                          
        // Todo add your handling code here:
    }                                         

    public static voID main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setTing code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available,stay with the default look and feel.
         * For details see http://download.Oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.HTML 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelinfo info : javax.swing.UIManager.geTinstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getname())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassname());
                    break;
                }
            }
        } catch (ClassnotFoundException eX) {
            java.util.logging.Logger.getLogger(Home.class.getname()).log(java.util.logging.Level.SEVERE,eX);
        } catch (InstantiationException eX) {
            java.util.logging.Logger.getLogger(Home.class.getname()).log(java.util.logging.Level.SEVERE,eX);
        } catch (illegalaccessexception eX) {
            java.util.logging.Logger.getLogger(Home.class.getname()).log(java.util.logging.Level.SEVERE,eX);
        } catch (javax.swing.UnsupportedLookAndFeelException eX) {
            java.util.logging.Logger.getLogger(Home.class.getname()).log(java.util.logging.Level.SEVERE,eX);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokelater(new Runnable() {
            public voID run() {
                new Home().setVisible@R_618_6334@;
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JTextFIEld Bayar;
    private javax.swing.Jbutton Bersih;
    private javax.swing.Jbutton Hapus;
    private javax.swing.JTextFIEld Jumlah;
    private javax.swing.Jbutton lihat;
    private javax.swing.JTextFIEld Nama;
    private javax.swing.Jbutton OK;
    public javax.swing.Jtable Tabl;
    private javax.swing.Jbutton Tambah;
    private javax.swing.JTextFIEld @R_228_10586@l;
    private javax.swing.Jbutton Ubah;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JscrollPane JscrollPane1;
    private java.awt.Menu menu1;
    private java.awt.Menu menu2;
    private java.awt.PopupMenu popupMenu1;
    // End of variables declaration                   
}

在另一个类中使用方法时总是出错 我曾尝试在 jtable 中获取一些值并将其发送到另一个类 抱歉，这是我在那里的第一个问题，我不知道它的字符串有限，所以我从 netbeans jframe 中删除了代码 谢谢

解决方法

您的堆栈跟踪指出在 tugasakhir.Home.TambahActionPerformed(Home.java:285) 处抛出 NullPointerException，因此错误位于以下行之一：

    private void TambahActionPerformed(java.awt.event.ActionEvent evt) {                                       
        // TODO add your handling code here
        
        //Inisialisasi Variable\
        String nama = Nama.getText();
        int jumlah = Integer.valueOf(Jumlah.getText());
        
        //Kirim data
        dc.tambahini(nama,jumlah);
        
    }

正好在第 285 行，但由于我不知道它是哪一行，所以我需要知道您文件中的第 285 行是哪一行。

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