Java JFrame布局在重新打开时不断变化

Question

所以我在我的Java应用程序中发现了JFrames之一的这个奇怪的事情，似乎在我重新打开布局后，我的组件的定位只是改变了。我习惯使用springLayout来定位我的组件，在我的应用程序中大约12帧，这是我第一次看到这样的事情发生。

这是我的代码：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.DecimalFormat;
import java.text.NumberFormat;

public class Edits extends JFrame implements ActionListener{
    //change price
    JLabel currentPrice = new JLabel("Current Price");
    JLabel changePrice = new JLabel("New Price");
    JFormattedTextField oldprice = new JFormattedTextField(new DecimalFormat("#0.000"));
    JFormattedTextField newprice = new JFormattedTextField(new DecimalFormat("#0.000"));
    JButton okPrice = new JButton("Save Changes");
    JButton closePrice = new JButton("Close");

    //change user info
    JLabel currentUser = new JLabel();
    JLabel changeUser = new JLabel();
    JLabel currentPass = new JLabel();
    JLabel changePass = new JLabel();
    JLabel confirmPass = new JLabel();
    JTextField oldUser = new JTextField();
    JTextField newUser = new JTextField();
    JPasswordField oldPass = new JPasswordField();
    JPasswordField newPass = new JPasswordField();
    JPasswordField confirmNewPass = new JPasswordField();
    JButton okUser = new JButton("Save Changes");
    JButton closeUser = new JButton("Close");

    //change purchased quantity
    JLabel currentQte = new JLabel();
    JLabel changeQte = new JLabel();
    JFormattedTextField oldQte = new JFormattedTextField(NumberFormat.getIntegerInstance());
    JFormattedTextField newQte = new JFormattedTextField(NumberFormat.getIntegerInstance());
    JButton okQte = new JButton("Save Changes");
    JButton closeQte = new JButton("Close");

    public Edits() {
        super();
    }

    public void changePrice() {
        //init frame
        this.setTitle("Chnage Medicine's Price");
        this.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        JFrame.setDefaultLookAndFeelDecorated(false);
        Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
        this.setLocation(dim.width/6-this.getSize().width/2, dim.height/16-this.getSize().height/2);
        this.setSize(350, 170);
        this.setResizable(false);
        this.setVisible(true);
        //init sizes
        Dimension labels = new Dimension(100,25);
        Dimension inputs = new Dimension(200,25);
        Dimension btn = new Dimension(80,35);
        Dimension btn1 = new Dimension(120,35);
        //Labels size
        currentPrice.setSize(labels);
        currentPrice.setMaximumSize(labels);
        currentPrice.setMinimumSize(labels);
        currentPrice.setPreferredSize(labels);
        changePrice.setSize(labels);
        changePrice.setMaximumSize(labels);
        changePrice.setMinimumSize(labels);
        changePrice.setPreferredSize(labels);
        //inputs size
        oldprice.setSize(inputs);
        oldprice.setMaximumSize(inputs);
        oldprice.setMinimumSize(inputs);
        oldprice.setPreferredSize(inputs);
        newprice.setSize(inputs);
        newprice.setMaximumSize(inputs);
        newprice.setMinimumSize(inputs);
        newprice.setPreferredSize(inputs);
        //button sizes
        okPrice.setSize(btn1);
        okPrice.setMaximumSize(btn1);
        okPrice.setMinimumSize(btn1);
        okPrice.setPreferredSize(btn1);
        closePrice.setSize(btn);
        closePrice.setMaximumSize(btn);
        closePrice.setMinimumSize(btn);
        closePrice.setPreferredSize(btn);
        this.add(currentPrice);
        this.add(oldprice);
        this.add(changePrice);
        this.add(newprice);
        this.add(okPrice);
        this.add(closePrice);
        //set layout
        SpringLayout layout = new SpringLayout();
        this.setLayout(layout);
        //old label
        layout.putConstraint(SpringLayout.NORTH, currentPrice, 15, SpringLayout.NORTH, this);
        layout.putConstraint(SpringLayout.WEST, currentPrice, 20, SpringLayout.WEST, this);
        //old input
        layout.putConstraint(SpringLayout.NORTH, oldprice, 15, SpringLayout.NORTH, this);
        layout.putConstraint(SpringLayout.WEST, oldprice, 10, SpringLayout.EAST, currentPrice);
        //new label
        layout.putConstraint(SpringLayout.NORTH, changePrice, 15, SpringLayout.SOUTH, currentPrice);
        layout.putConstraint(SpringLayout.WEST, changePrice, 20, SpringLayout.WEST, this);
        //new input
        layout.putConstraint(SpringLayout.NORTH, newprice, 15, SpringLayout.SOUTH, currentPrice);
        layout.putConstraint(SpringLayout.WEST, newprice, 10, SpringLayout.EAST, changePrice);
        //OK 
        layout.putConstraint(SpringLayout.NORTH, okPrice, 15, SpringLayout.SOUTH, newprice);
        layout.putConstraint(SpringLayout.WEST, okPrice, 65, SpringLayout.WEST, this);
        //close
        layout.putConstraint(SpringLayout.NORTH, closePrice, 15, SpringLayout.SOUTH, newprice);
        layout.putConstraint(SpringLayout.WEST, closePrice, 20, SpringLayout.EAST, okPrice);
    }

    @Override
    public void actionPerformed(ActionEvent e) {

    }

}

这是我想要的布局图片：

这就是持续发生的事情：

有谁知道什么是错的？