使用超級和toString更新JTextArea

Question

我想在Person類中使用toString來追加EmployeesApplet類中的JTextArea。最終輸出結果如下

對於Person類，它需要實例變量是私有的，一個構造函數和一個toString方法，現在我只是試圖讓它顯示名稱，所以我可以弄清楚如何去做其他 我會如何完成我的Person類？

的EmployeesApplet低於

import javax.swing.*; 
import java.awt.*; 
import java.awt.event.*; 

public class EmployeesApplet extends JApplet implements ActionListener 
{ 
    public JButton    sd = new JButton ("Salaried"); 
    public JButton    hr = new JButton ("Hourly"); 
    public JButton    cm = new JButton ("Commissioned"); 
    public JButton    cl = new JButton ("Clear"); 

    private final int FIELDS  = 8, 
         FIELD_WIDTH = 20; 

    private String[]  strings  = new String[FIELDS]; 
    private TextFieldWithLabel[] tf = new TextFieldWithLabel[FIELDS]; 
    private JTextArea ta   = new JTextArea(5,25); 

    String[] s = {"First Name", "Last Name", "Employee ID", "(a) Salaried: Weekly Salary", "(b1) Hourly 1: Rate Per Hour", 
        "(b2) Hourly 2: Hours Worked" , "(c1) Commissioned: Rate", "(c2) Commissioned: Gross Sales" }; 

    public void init() 
    { 
     this.setSize(420, 310); 

     //---------------------- 
     // Set up the Structure 
     //---------------------- 

     Container c = getContentPane(); 
     JPanel f = new JPanel(new FlowLayout()); 
     JPanel b = new JPanel(new BorderLayout(2,0)); 

     JPanel glb = new JPanel(new GridLayout(8,1,0,2)); 
     JPanel gtf = new JPanel(new GridLayout(8,1,0,2)); 
     JPanel flb = new JPanel(new FlowLayout()); 


     // Add FlowLayout to the container 
     c.add(f); 
     // Add BorderLayout to the FlowLayout 
     f.add(b); 

     //--------------------------------------- 
     //Add JPanels to the BorderLayout regions 
     //--------------------------------------- 

     // Add JLables to GridLayout in West 
     b.add(glb, BorderLayout.WEST); 
     for (int i = 0; i < tf.length; i++) 
     { 
     tf[i] = new TextFieldWithLabel(s[i], FIELD_WIDTH); 
     glb.add(tf[i].getLabel()); 
     } 

     // Add JTextFeilds to GridLayout in East 
     b.add(gtf, BorderLayout.EAST); 
     for (int i = 0; i < tf.length; i++) 
     { 
     tf[i] = new TextFieldWithLabel(s[i], FIELD_WIDTH); 
     tf[i].getTextField(); 
     gtf.add(tf[i].getTextField()); 
     } 

     // Add JButtons to FlowLayout in South 
     b.add(flb, BorderLayout.SOUTH); 

     flb.add(sd); 
     flb.add(hr); 
     flb.add(cm); 
     flb.add(cl); 

     sd.addActionListener(this); 
     hr.addActionListener(this); 
     cm.addActionListener(this); 
     cl.addActionListener(this); 

     // Add JTextArea and make it not editable 
     f.add(ta); 
     ta.setEditable(false); 

    } 

    //--------------------------------------- 
    // Read all the JTextFields and 
    // save the contents in a parallel array 
    //--------------------------------------- 
    private void readFields() 
    { 
     for (int i = 0; i < tf.length; i++) // or FIELDS 
     strings[i] = tf[i].getText(); 
    } 

    private boolean fieldsExist(int i, int i2) 
    { 
     if(i == 0 && i2 == 3) // Checks Salaried worker 
     { 
     if(tf[0].getText() == null || tf[0].getText().length() == 0) 
     { 
      showStatus("First Name field is empty"); // Diplays error message in status area 
      tf[0].getTextField().requestFocus(); // Places focus in JTextField 
      return false; 
     } 
     else if(tf[1].getText() == null || tf[1].getText().length() == 0) 
     { 
      showStatus("Last Name field is empty"); 
      tf[1].getTextField().requestFocus(); 
      return false; 
     } 
     else if(tf[2].getText() == null || tf[2].getText().length() == 0) 
     { 
      showStatus("Employee ID field is empty"); 
      tf[2].getTextField().requestFocus(); 
      return false; 
     } 
     else if(tf[3].getText() == null || tf[3].getText().length() == 0) 
     { 
      showStatus("(a)Salried: Weekly Salary field is empty"); 
      tf[3].getTextField().requestFocus(); 
      return false; 
     }  
     else   
     return true; 
     } 

     if(i == 0 && i2 == 2) // Checks Hourly worker 
     { 
     if(tf[0].getText() == null || tf[0].getText().length() == 0) 
     { 
      showStatus("First Name field is empty"); 
      tf[0].getTextField().requestFocus(); 
      return false; 
     } 
     else if(tf[1].getText() == null || tf[1].getText().length() == 0) 
     { 
      showStatus("Last Name field is empty"); 
      tf[1].getTextField().requestFocus(); 
      return false; 
     } 
     else if(tf[2].getText() == null || tf[2].getText().length() == 0) 
     { 
      showStatus("Employee ID field is empty"); 
      tf[2].getTextField().requestFocus(); 
      return false; 
     } 
     else   
     return true; 
     } 

     if(i == 4 && i2 == 5) // Checks Hourly worker the second time 
     { 
     if(tf[4].getText() == null || tf[4].getText().length() == 0) 
     { 
      showStatus("(b1) Hourly 1: Rate Per Hour field is empty"); 
      tf[5].getTextField().requestFocus(); 
      return false; 
     } 
     else if(tf[5].getText() == null || tf[5].getText().length() == 0) 
     { 
      showStatus("(b2) Hourly 2: Hours Worked field is empty"); 
      tf[5].getTextField().requestFocus(); 
      return false; 
     } 
     else   
     return true; 
     } 

     if(i == 0 && i2 == 2) // Checks Commissioned worker 
     { 
     if(tf[0].getText() == null || tf[0].getText().length() == 0) 
     { 
      showStatus("First Name field is empty"); 
      tf[0].getTextField().requestFocus(); 
      return false; 
     } 
     else if(tf[1].getText() == null || tf[1].getText().length() == 0) 
     { 
      showStatus("Last Name field is empty"); 
      tf[1].getTextField().requestFocus(); 
      return false; 
     } 
     else if(tf[2].getText() == null || tf[2].getText().length() == 0) 
     { 
      showStatus("Employee ID field is empty"); 
      tf[2].getTextField().requestFocus(); 
      return false; 
     }  
     else  
     return true; 
     } 

     if(i == 6 && i2 == 7) // Checks Commissioned second time 
     { 
     if(tf[6].getText() == null || tf[6].getText().length() == 0) 
     { 
      showStatus("(c1)Commissioned: Rate field is empty"); 
      tf[0].getTextField().requestFocus(); 
      return false; 
     } 
     else if(tf[7].getText() == null || tf[7].getText().length() == 0) 
     { 
      showStatus("(c2)Commissioned: Ratefield is empty"); 
      tf[1].getTextField().requestFocus(); 
      return false; 
     }  
     else  
     return true; 
     } 
     return false; 

     } 


    private boolean fieldsEmpty(int i, int i2, String[] a) 
    { 
     if(i == 4 && i2 == 7) // checks salaried 
     { 
     for (int index = 4; index <= 7; index++) 
     { 
      if(tf[index].getText().length() != 0) 
      { 
      showStatus(a[index] + " should be empty"); // Diplays error message in status area 
      tf[index].getTextField().requestFocus(); // Places focus in JTextField 
      return true; 
      } 
      else return false; 
     } // end for 
     } // end if 

     if (i == 3 && i2 == 3) // checks hourly first time 
     { 
     if(tf[3].getText().length() != 0) 
     { 
      showStatus(a[3] + " field should be empty"); 
      tf[3].getTextField().requestFocus(); 
      return true; 
     } 
     } // end if 

     if(i == 6 && i2 == 7) // checks hourly second time 
     {  
     for (int index = 6; index <= 7; index++) 
     { 
      if(tf[index].getText().length() != 0) 
      { 
      showStatus(a[index] + " field should be empty"); 
      tf[index].getTextField().requestFocus(); 
      return true; 
      } 

     } // end for 
     } // end if 

     if(i == 3 && i2 == 5) // checks commissioned 
     {  
     for (int index = 3; index <= 5; index++) 
     { 
      if(tf[index].getText().length() != 0) 
      { 
      showStatus(a[index] + " field should be empty"); 
      tf[index].getTextField().requestFocus(); 
      return true; 
      } 

     } // end for 
     } // end if 

     return false; 
    } 

    public void actionPerformed(ActionEvent e) 
    { 
     showStatus(""); 

     if (e.getSource() == cl) // Executes clear button is clicked 
     { 
     for (int i = 0; i < FIELDS; i++) 
     { 
      tf[i].getTextField().setText(""); 
      tf[0].getTextField().requestFocus(); 
     } 
     } // End clear if  

     if (e.getSource() != cl) 
     { 

     if(e.getSource() == sd) // checks for salaried employee 
     { 
      showStatus("Salaried"); 
      fieldsExist(0,3); 
      fieldsEmpty(4,7, s); 
      ta.append("lol"); 
     } // end salaried 

     if(e.getSource() == hr) // checks for hourly employee 
     { 
      showStatus("Hourly"); 
      fieldsExist(0,2); 
      fieldsExist(4,5); 
      fieldsEmpty(3,3, s); 
      fieldsEmpty(6,7, s); 
     } // end hourly 

     if(e.getSource() == cm) // checks for commissioned employee 
     { 
      showStatus("Commissioned"); 
      fieldsExist(0,2); 
      fieldsExist(6,7); 
      fieldsEmpty(3,5, s); 
     } // end commisssioned 
     } // end if 
    } // End of actionPerformed 

} 

，這是Person類

public abstract class Person 
{ 
    private int i; // private instance variables 

    public Person(int i) // one constructor 
    { 


    } 




    public String toString() {return ??? ;} // toString method 

} 

Answer 1

它看起來像你的Person類需要像firstName和lastName字符串變量。這是我將用於我的人類：

public class Person extends EmployeesApplet { 
    private int i; // private instance variables 
    private String firstName; 
    private String lastName; 

    public Person(int i) // one constructor 
    { 
     firstName = ""; 
     lastName = ""; 
    } 

    public String getFirstName() 
    { 
     return firstName; 
    } 

    public void setFirstName(String firstName) 
    { 
     this.firstName = firstName; 
    } 

    public String getLastName() 
    { 
     return lastName; 
    } 

    public void setLastName(String lastName) 
    { 
     this.lastName = lastName; 
    } 

    public String toString() 
    { 
     return getfirstName() + " " + getLastName(); 
    } // toString method 

}