java - FlowLayout.CENTER 未使组件居中

Question

我使用 FlowLayout.CENTER 将字符串和一些复选框居中，但它没有将它们居中。我以前用过这个并且效果很好。这是代码:

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

public class pizza extends JFrame {
//row 1
  JPanel row1 = new JPanel();
  JLabel select = new JLabel("Please select the size you would like"); 
//row 2
  JPanel row2 = new JPanel();
  JCheckBox ninein = new JCheckBox("9 inch, $5.00", false);
  JCheckBox twelvein = new JCheckBox("12 inch, $10.00", false);
  JCheckBox seventeenin = new JCheckBox("17 inch, $15.00", false);
//row 3
  JPanel row3 = new JPanel();
  JLabel toppingslab = new JLabel("Please select your toppings");
  JCheckBox cheese = new JCheckBox("Cheese, .50");
  JCheckBox pepperoni = new JCheckBox("Pepperoni, .50");
  JCheckBox onions = new JCheckBox("Onions, .50");
  JCheckBox peppers = new JCheckBox("Peppers, .50");
  JCheckBox bacon = new JCheckBox("Bacon! Free (because it's bacon)");
//row4
  JPanel row4 = new JPanel();
  JLabel totallab = new JLabel("Total");
  JTextField total = new JTextField(10);

public pizza(){
    setTitle("Pizza Ordering");
    setSize(500,500);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setVisible(true);
  total.setEnabled(false);

FlowLayout one = new FlowLayout(FlowLayout.CENTER);
  setLayout(one);

  row1.add(select);
  add(row1);

  row2.add(ninein);
  row2.add(twelvein);
  row2.add(seventeenin); 
  add(row2);

GridLayout two = new GridLayout(6,2);
  row3.setLayout(two);

  row3.add(toppingslab);
  row3.add(cheese);
  row3.add(pepperoni);
  row3.add(onions);
  row3.add(peppers);
  row3.add(bacon);
  add(row3);

FlowLayout three = new FlowLayout(FlowLayout.RIGHT);
  setLayout(three);

  row4.add(totallab);
  row4.add(total);
  add(row4);  
    } 
public static void main(String[] args) {
    pizza pizz = new pizza();
}
}

RIGHT 或 LEFT 都没有什么区别，它只是将其向右对齐。

Answer 1

所有组件都右对齐的原因是您在此处将 JFrame 的布局重置为 FlowLayout.RIGHT:

FlowLayout three = new FlowLayout(FlowLayout.RIGHT);
setLayout(three);

这取代了之前对居中对齐组件的调用。