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我在计算器类中更新JFrame的背景颜色时遇到问题。 “frame.getContentPane（）。setBackground（Color.BLACK）;”方法调用不更新帧的背景颜色外观。相反，背景颜色保持不变;灰白色。该代码相当容易找到位于第一个方法“public void addComponents”。先谢谢你。JFrame不更新背景颜色
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
public static JFrame frame = new JFrame("Calculator");
public JPanel panel = new JPanel(new GridLayout(6,0,4,4));
public double currentNumber, nextNumber, total;
public boolean numberPresent = false;
public boolean addition = false, subtraction = false, multiplication = false, division = false;
public void addComponents(int x, int y) {
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(x,y);
frame.getContentPane().setBackground(Color.BLACK);
frame.setLocationRelativeTo(null);
frame.setResizable(false);
JButton button1 = new JButton("0");
button1.addActionListener(this);
button1.setActionCommand("ZERO");
button1.setPreferredSize(new Dimension(20,20));
JButton button2 = new JButton("1");
button2.addActionListener(this);
button2.setActionCommand("ONE");
button2.setPreferredSize(new Dimension(20,20));
JButton button3 = new JButton("2");
button3.addActionListener(this);
button3.setActionCommand("TWO");
button3.setPreferredSize(new Dimension(20,20));
JButton button4 = new JButton("3");
button4.addActionListener(this);
button4.setActionCommand("THREE");
button4.setPreferredSize(new Dimension(20,20));
JButton button5 = new JButton("4");
button5.addActionListener(this);
button5.setActionCommand("FOUR");
button5.setPreferredSize(new Dimension(20,20));
JButton button6 = new JButton("5");
button6.addActionListener(this);
button6.setActionCommand("FIVE");
button6.setPreferredSize(new Dimension(20,20));
JButton button7 = new JButton("6");
button7.addActionListener(this);
button7.setActionCommand("SIX");
button7.setPreferredSize(new Dimension(20,20));
JButton button8 = new JButton("7");
button8.addActionListener(this);
button8.setActionCommand("SEVEN");
button8.setPreferredSize(new Dimension(20,20));
JButton button9 = new JButton("8");
button9.addActionListener(this);
button9.setActionCommand("EIGHT");
button9.setPreferredSize(new Dimension(20,20));
JButton button10 = new JButton("9");
button10.addActionListener(this);
button10.setActionCommand("NINE");
button10.setPreferredSize(new Dimension(20,20));
JButton button11 = new JButton("CLEAR");
button11.addActionListener(this);
button11.setActionCommand("CLEAR");
button11.setPreferredSize(new Dimension(20,20));
JButton button12 = new JButton("+");
button12.addActionListener(this);
button12.setActionCommand("+");
button12.setPreferredSize(new Dimension(20,20));
JButton button13 = new JButton("-");
button13.addActionListener(this);
button13.setActionCommand("-");
button13.setPreferredSize(new Dimension(20,20));
JButton button14 = new JButton("x");
button14.addActionListener(this);
button14.setActionCommand("x");
button14.setPreferredSize(new Dimension(20,20));
JButton button15 = new JButton("/");
button15.addActionListener(this);
button15.setActionCommand("/");
button15.setPreferredSize(new Dimension(20,20));
JButton button16 = new JButton("=");
button16.addActionListener(this);
button16.setActionCommand("=");
button16.setPreferredSize(new Dimension(20,20));
panel.add(button8);
panel.add(button9);
panel.add(button10);
panel.add(button5);
panel.add(button6);
panel.add(button7);
panel.add(button2);
panel.add(button3);
panel.add(button4);
panel.add(button1);
panel.add(button12);
panel.add(button13);
panel.add(button16);
panel.add(button14);
panel.add(button15);
panel.add(button11);
frame.setContentPane(panel);
frame.setVisible(true);
}
public void actionPerformed(ActionEvent ea) {
String action = ea.getActionCommand();
if (numberPresent = true && action.equals("ZERO")) {
nextNumber = currentNumber;
currentNumber = 0;
System.out.print("0");
}
if (numberPresent = false && action.equals("ZERO")) {
currentNumber = 0;
numberPresent = true;
System.out.print("0");
}
if (numberPresent = true && action.equals("ONE")) {
nextNumber = currentNumber;
currentNumber = 1;
System.out.print("1");
}
if (numberPresent = false && action.equals("ONE")) {
currentNumber = 1;
numberPresent = true;
System.out.print("1");
}
if (numberPresent = true && action.equals("TWO")) {
nextNumber = currentNumber;
currentNumber = 2;
System.out.print("2");
}
if (numberPresent = false && action.equals("TWO")) {
currentNumber = 2;
numberPresent = true;
System.out.print("2");
}
if (numberPresent = true && action.equals("THREE")) {
nextNumber = currentNumber;
currentNumber = 3;
System.out.print("3");
}
if (numberPresent = false && action.equals("THREE")) {
currentNumber = 3;
numberPresent = true;
System.out.print("3");
}
if (numberPresent = true && action.equals("FOUR")) {
nextNumber = currentNumber;
currentNumber = 4;
System.out.print("4");
}
if (numberPresent = false && action.equals("FOUR")) {
currentNumber = 4;
numberPresent = true;
System.out.print("4");
}
if (numberPresent = true && action.equals("FIVE")) {
nextNumber = currentNumber;
currentNumber = 5;
System.out.print("5");
}
if (numberPresent = false && action.equals("FIVE")) {
currentNumber = 5;
numberPresent = true;
System.out.print("5");
}
if (numberPresent = true && action.equals("SIX")) {
nextNumber = currentNumber;
currentNumber = 6;
System.out.print("6");
}
if (numberPresent = false && action.equals("SIX")) {
currentNumber = 6;
numberPresent = true;
System.out.print("6");
}
if (numberPresent = true && action.equals("SEVEN")) {
nextNumber = currentNumber;
currentNumber = 7;
System.out.print("7");
}
if (numberPresent = false && action.equals("SEVEN")) {
currentNumber = 7;
numberPresent = true;
System.out.print("7");
}
if (numberPresent = true && action.equals("EIGHT")) {
nextNumber = currentNumber;
currentNumber = 8;
System.out.print("8");
}
if (numberPresent = false && action.equals("EIGHT")) {
currentNumber = 8;
numberPresent = true;
System.out.print("8");
}
if (numberPresent = true && action.equals("NINE")) {
nextNumber = currentNumber;
currentNumber = 9;
System.out.print("9");
}
if (numberPresent = false && action.equals("NINE")) {
currentNumber = 9;
numberPresent = true;
System.out.print("9");
}
if (action.equals("CLEAR")) {
currentNumber = 0;
nextNumber = 0;
total = 0;
System.out.println("CLEARED");
}
if (action.equals("=")) {
numberPresent = false;
if (addition) {
System.out.println(" = " + (currentNumber + nextNumber));
total = (currentNumber + nextNumber);
currentNumber = total;
addition = false;
}
if (subtraction) {
System.out.println(" = " + (nextNumber - currentNumber));
total = (currentNumber - nextNumber);
currentNumber = total;
subtraction = false;
}
if (multiplication) {
System.out.println(" = " + (currentNumber * nextNumber));
total = (currentNumber * nextNumber);
currentNumber = total;
multiplication = false;
}
if (division) {
System.out.println(" = " + (nextNumber/ currentNumber));
total = (nextNumber/currentNumber);
currentNumber = total;
division = false;
}
}
if (action.equals("+")) {
addition = true;
System.out.print(" + ");
}
else if (action.equals("-")) {
subtraction = true;
System.out.print(" - ");
}
else if (action.equals("x")) {
multiplication = true;
System.out.print(" x ");
}
else if (action.equals("/")) {
division = true;
System.out.print("/");
}
}
public static void main(String[] args) {
System.out.println("Only handles 1 digit inputs at once. *Almost* Fully Functional");
Calculator calc = new Calculator();
calc.addComponents(260, 325);
}
}
哇..它不应该需要大约280 LOC显示 “无法设置BG”！为了更快地获得更好的帮助，请发布[MCVE]（http://stackoverflow.com/help/mcve）（最小，完整，可验证示例）。 –
1）请参阅[我是否应避免使用Swing中的set（Preferred | Maximum | Minimum）Size方法？]（http://stackoverflow.com/q/7229226/418556）（是）。按钮是使用大字体或给按钮大利润。对于方形按钮，扩展组件或使用方形图标（并且不包含文本）。 2）另请参阅[工作计算器]（http://stackoverflow.com/a/7441804/418556）。 –
我会记住任何未来的问题。感觉就像展示整个编码部分，以降低背景颜色变化抑制的可能性。事实证明，这只是一个菜鸟的错误，它可能会在几秒钟的阅读和“Ctrl + X”+“Ctrl + V”中被阻止。我会尽量保持简短，以便将来解决问题。 –