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[英]Adding a LinkedList to a LinkedList that contains LinkedLists and changing the added LinkedList
[英]linkedList is empty although elements added to it
我創建了一個包含一個按鈕的“ frame1”,因此,如果我單擊該按鈕,則執行按鈕操作的方法將檢查LinkedList是否為空,如果是,它將設置“ addEmployee”框架可見,其中包含radioButton調用addEmployees_Auto,並且單擊時,它將從frame1調用方法“ add_Auto”。 這應該填充frame1中的linkedList,但是如果我再次單擊該按鈕,LinkedList再次為空。 為什么? 不應該填充LinkedList嗎?
這是“ frame1”
public class Frame1 extends javax.swing.JFrame {
LinkedList <Employee>list2=new LinkedList <Employee>();
....
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
System.out.println("size="+list2.size());
if(list2.isEmpty())
new AddEmployees.setVisible(true);
}
public void addEmployees_Auto()
{
list2.add(new Employee(20910733,"Ahmed","Manager",2700));
list2.add(new Employee(20910835,"Omar","Teaacher",2100));
list2.add(new Employee(20910674,"Mohammed","Manager",3000));
list2.add(new Employee(20910955,"Kareem","",2700));
list2.add(new Employee(20910921,"Ameer","teacher",2500));
}
}
AddEmployee框架:
public class AddEmployees extends javax.swing.JFrame {
...
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt)
{
if(jRadioButton2.isSelected()){
new Frame1().addEmployees_Auto();
this.setVisible(false);
}
}
我認為這是因為您正在執行以下操作:
new Frame1()
每次在AddEmployees
類中,因此每次創建新的鏈表時,該鏈表始終為空。 您需要傳遞對Frame1
調用實例的引用,例如
new AddEmployees(this)
從Frame1
類,然后將適當的構造函數添加到您的AddEmployees
類,例如
public AddEmployees(JFrame parent) { ... }
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