Java中的JPanel的函数setBounds()的用法误解

class CoraseButtonPanel extends JPanel{ public CoraseButtonPanel(){ this.setLayout(null); this.setBounds(0,0,512,512); this.setBorder( BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.BLACK,1), "Coarse Adjustment",TitledBorder.DEFAULT_POSITION,TitledBorder.TOP,new java.awt.Font("Times New Roman",0,20))); CoraseStartButton=new JButton("Start"); CoraseStartButton.setSize(80,30); CoraseStartButton.setBounds(180,460,80,30); CorasePreceedButton = new JButton("Preceed"); CorasePreceedButton.setSize(100,30); CorasePreceedButton.setBounds(280,460,100,30); CoraseCancleButton = new JButton("Cancle"); CoraseCancleButton .setSize(80,30); CoraseCancleButton.setBounds(400,460,80,30); CorasePreceedButton.setEnabled(false); CoraseCancleButton.setEnabled(false); CoraseStartButton.addActionListener(new CoraseStartAction()); CorasePreceedButton.addActionListener(new CorasepreceedAction()); CoraseCancleButton.addActionListener(new CorasecancleAction()); add(CoraseStartButton); add(CorasePreceedButton); add(CoraseCancleButton); } } class Joint1ButtonPanel extends JPanel{ public Joint1ButtonPanel(){ this.setLayout(null); this.setBounds(512,0,512,512); this.setBorder(BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.BLACK,1), "Joint1 Adjustment",TitledBorder.DEFAULT_POSITION,TitledBorder.TOP,new java.awt.Font("Times New Roman",0,20))); Joint1BackButton=new JButton("Back"); Joint1BackButton.setSize(80,30); Joint1BackButton.setBounds(700,460,80,30); Joint1PreceedButton = new JButton("Preceed"); Joint1PreceedButton.setSize(100,30); Joint1PreceedButton.setBounds(800,460,100,30); Joint1CancleButton = new JButton("Cancle"); Joint1CancleButton.setSize(80,30); Joint1CancleButton.setBounds(900,460,80,30); Joint1BackButton.setEnabled(false); Joint1PreceedButton.setEnabled(false); Joint1CancleButton .setEnabled(false); Joint1BackButton.addActionListener(new Joint1BackAction()); Joint1PreceedButton.addActionListener(new Joint1PreceedAction()); Joint1CancleButton.addActionListener(new Joint1CancleAction()); add(Joint1BackButton); add(Joint1PreceedButton); add(Joint1CancleButton); } }