嘗試通過將JTextField數據添加到數組來向JButton添加功能

Question

我試圖將數據從JTextField組件添加到我的學生數組中。但我不斷收到錯誤。我也不知道如何引用和使用我的mainGui類中的學生課程的變量。

這是我的GUI類

public class mainGui extends javax.swing.JFrame { 

    /** 
    * Creates new form mainGui 
    */ 
    ArrayList<Student> student = new ArrayList<>(); 

    public mainGui() { 
     initComponents(); 
    } 

    /** 
    * This method is called from within the constructor to initialize the form. 
    * WARNING: Do NOT modify this code. The content of this method is always 
    * regenerated by the Form Editor. 
    */ 
    @SuppressWarnings("unchecked") 
    // <editor-fold defaultstate="collapsed" desc="Generated Code">       
    private void initComponents() { 

     jLabel1 = new javax.swing.JLabel(); 
     sName = new javax.swing.JTextField(); 
     jLabel2 = new javax.swing.JLabel(); 
     sId = new javax.swing.JTextField(); 
     jLabel3 = new javax.swing.JLabel(); 
     sYear = new javax.swing.JTextField(); 
     jLabel4 = new javax.swing.JLabel(); 
     sEmail = new javax.swing.JTextField(); 
     jButton1 = new javax.swing.JButton(); 
     setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 

     jLabel1.setText("jLabel1"); 

     sName.setText("jTextField1"); 

     jLabel2.setText("jLabel2"); 

     sId.setText("jTextField2"); 

     jLabel3.setText("jLabel3"); 

     sYear.setText("jTextField3"); 

     jLabel4.setText("jLabel4"); 

     sEmail.setText("jTextField4"); 
     sEmail.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       sEmailActionPerformed(evt); 
      } 
     }); 

     jButton1.setText("jButton1"); 
     jButton1.addActionListener(new java.awt.event.ActionListener() { 
      public void actionPerformed(java.awt.event.ActionEvent evt) { 
       jButton1ActionPerformed(evt); 
      } 
     }); 

     javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); 
     getContentPane().setLayout(layout); 
     layout.setHorizontalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(layout.createSequentialGroup() 
       .addGap(28, 28, 28) 
       .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING) 
        .addComponent(jLabel4) 
        .addComponent(jLabel3) 
        .addComponent(jLabel2) 
        .addComponent(jLabel1)) 
       .addGap(33, 33, 33) 
       .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
        .addComponent(sName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
        .addComponent(sEmail, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
        .addGroup(layout.createSequentialGroup() 
         .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
          .addComponent(sId, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) 
          .addComponent(sYear, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
         .addGap(45, 45, 45) 
         .addComponent(jButton1))) 
       .addContainerGap(105, Short.MAX_VALUE)) 
     ); 
     layout.setVerticalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGroup(layout.createSequentialGroup() 
       .addGap(39, 39, 39) 
       .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
        .addComponent(jLabel1) 
        .addComponent(sName, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
       .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
        .addGroup(layout.createSequentialGroup() 
         .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) 
         .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
          .addComponent(jLabel2) 
          .addComponent(sId, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
         .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) 
         .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
          .addComponent(jLabel3) 
          .addComponent(sYear, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))) 
        .addGroup(layout.createSequentialGroup() 
         .addGap(29, 29, 29) 
         .addComponent(jButton1))) 
       .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED) 
       .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) 
        .addComponent(jLabel4) 
        .addComponent(sEmail, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) 
       .addContainerGap(134, Short.MAX_VALUE)) 
     ); 

     pack(); 
    }// </editor-fold>       

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {           
     // TODO add your handling code here: 
     student.add(sEmail.getText()); 
     student.add(sYear.getText()); 
     student.add(sId.getText()); 
     student.add(sName.getText());   
    }  

學生類

package student; 
import java.util.ArrayList; 

public class Student { 

    ArrayList<Student> student = new ArrayList<>(); 

    /** 
    * @param args the command line arguments 
    */ 
    private String sName; 
    private int sID; 
    private String sEmail; 
    private int sYear; 

    public static void main(String[] args) { 
     // TODO code application logic here   
    } 

    public Student(String studentName, int studentID, String studentEmail, int yearOfStudy) 
    { 
     this.sName = sName; 
     this.sID = sID; 
     this.sEmail = sEmail; 
     this.sYear = sYear;  
    } 
} 

Answer 1

您的學生的ArrayList是學生類型，ArrayList<Student>的，所以你只能增加學生對象到它，而不是字符串作爲你正在努力。因此，這不會編譯：

 student.add(sEmail.getText()); 
    student.add(sYear.getText()); 
    student.add(sId.getText()); 
    student.add(sName.getText()); 

，而不是從你的JTextFields將得到字符串，轉換需要是整數到整數，創建與數據一個Student對象的字符串，然後添加到學生的數組列表。

在僞代碼

：

// inside of actionPerformed: 
get name String from sName, put into a String local variable 
get email String from sEmail, put into a String local variable 
get year String from sYear, convert to an int and put into a int local variable 
get id String from sID, convert to an int and put into a int local variable 

create a Student object from the local variables 
add to student ArrayList 

方建議：

• 重命名學生ArrayList的學生或studentsList
• 把那學生ArrayList<Student>你的學生類。它不應該在那裏，並且只會讓你陷入困境。
• 給你的學生類訪問器（getter）方法，以便外部類可以找到它的字段的狀態。