用JAVA编写一个简单的屏幕变色程序，当用户单击“变色”按钮时，窗口颜色就自动地变成另外一种颜色。

import javaawt;

import javaawtevent;

import javaapplet;

public class ColorChange extends Applet implements MouseListener

{Button btn=new Button("变色");

public void init()

{btnaddMouseListener(this);

thisadd(btn);}//将鼠标事件注册

public void mouseEntered(MouseEvent e){

}

public void mouseExited(MouseEvent e){

setBackground(Colorwhite);}

public void mousePressed(MouseEvent e)

{}

public void mouseReleased(MouseEvent e)

{}

public void mouseClicked(MouseEvent e){

setBackground(Colorgreen);

repaint();

}

}

声明是指对象，定义才是指类比较好理解。

java里如何声明一个颜色类对象。

java里如何定义一个颜色类。

如果是第一种的话:   javaawtColor color;

如果是 第二种就是自定义类，需要看具体需求来，或者可以参考javaawtColor的源码。

import javaawt;

import javaawtevent;

public class adjustcolor implements AdjustmentListener, WindowListener {

Frame f=new Frame("调整颜色");

Label l1=new Label("调整滚动条，会改变初始颜色",LabelCENTER);

Label l2=new Label("此处显示颜色值",LabelCENTER);

Label l3=new Label("红",LabelCENTER);

Label l4=new Label("绿",LabelCENTER);

Label l5=new Label("蓝",LabelCENTER);

Scrollbar scr1=new Scrollbar(ScrollbarHORIZONTAL,0,10,0,265);

Scrollbar scr2=new Scrollbar(ScrollbarHORIZONTAL,0,10,0,265);

Scrollbar scr3=new Scrollbar(ScrollbarHORIZONTAL,0,10,0,265);

public adjustcolor(){

fadd(l1);

fadd(l2);

fadd(l3);

fadd(l4);

fadd(l5);

fadd(scr1);

fadd(scr2);

fadd(scr3);

fsetSize(400,350);

fsetVisible(true);

faddWindowListener(this);

fsetResizable(false);

l1setBackground(ColorGREEN);

scr1setBounds(35,225,360,25);

scr2setBounds(35,255,360,25);

scr3setBounds(35,285,360,25);

l1setBounds(0,0,400,200);

l2setBounds(0,310,400,30);

l3setBounds(0,225,30,30);

l4setBounds(0,255,30,30);

l5setBounds(0,285,30,30);

scr1addAdjustmentListener(this);

scr2addAdjustmentListener(this);

scr3addAdjustmentListener(this);

l1setBackground(ColorGREEN);

scr1setBackground(ColorRED);

scr2setBackground(ColorGREEN);

scr3setBackground(Colorblue);

}

public void adjustmentValueChanged(AdjustmentEvent e){

int a=scr1getValue();

int b=scr2getValue();

int c=scr3getValue();

l1setBackground(new Color(a,b,c)) ;

l2setText("红"+" "+"绿"+" "+"蓝"+" "+a+" "+b+" "+c);

l1setText(null);

}

public static void main(String[] args){

new adjustcolor();

}

public void windowActivated(WindowEvent arg0) {

// TODO Auto-generated method stub

}

public void windowClosed(WindowEvent arg0) {

}

public void windowClosing(WindowEvent arg0) {

Systemexit(0);

}

public void windowDeactivated(WindowEvent arg0) {

// TODO Auto-generated method stub

}

public void windowDeiconified(WindowEvent arg0) {

// TODO Auto-generated method stub

}

public void windowIconified(WindowEvent arg0) {

// TODO Auto-generated method stub

}

public void windowOpened(WindowEvent arg0) {

// TODO Auto-generated method stub

}

}

这是源代码 应该是你想要的

主类不需要更改，只需改一下Circlejava我呢见

import javaawtColor;

import javaawtGraphics;

import javaawtGridLayout;

import javaxswingJPanel;

public class Circle extends JPanel

{

public void paintComponent( Graphics g )

{

superpaintComponent( g );

int numFlag=0;

for ( int topLeft = 0; topLeft < 80; topLeft += 10 )

{

numFlag++;

if(numFlag%2==0)

gsetColor(Colorblue);//改变颜色

else

gsetColor(Colorwhite);//改变颜色

int radius = 160 - ( topLeft 2 );

gfillOval(topLeft + 10, topLeft + 25, radius, radius);//这是画圆

//gfillArc( topLeft + 10, topLeft + 25, radius, radius, 0, 360 );

}

thissetBackground(Colorred);

}

}

代码如下：

import javaawtDimension;

import javaawtFlowLayout;

import javautilHashMap;

import javautilMap;

import javaxswingJComboBox;

import javaxswingJFrame;

import javaxswingJTextField;

public class App extends JFrame {

private JComboBox<String> cbxColors;

private JTextField txtName;

private Map<String, Color> colorMap;

public App() {

thissetSize(300, 100);

thissetLocationRelativeTo(null);

thissetDefaultCloseOperation(JFrameEXIT_ON_CLOSE);

thissetLayout(new FlowLayout());

colorMap = new HashMap<>();

colorMapput("红", ColorRED);

colorMapput("绿", ColorGREEN);

colorMapput("蓝", ColorBLUE);

colorMapput("黄", ColorYELLOW);

cbxColors = new JComboBox(colorMapkeySet()toArray());

cbxColorssetPreferredSize(new Dimension(50, 23));

cbxColorsaddItemListener(e -> {

Color color = colorMapget(egetItem());

txtNamesetBackground(color);

});

thisadd(cbxColors);

txtName = new JTextField();

txtNamesetPreferredSize(new Dimension(100, 23));

txtNamesetBackground(ColorRED);

thisadd(txtName);

}

public static void main(String[] args) {

new App()setVisible(true);

}

}

运行结果：

参考。JColorChooser

可以用Java Swing里面的颜色选择器：JColorChooser

例子如下：

public class Color extends javaxswingJFrame {

public Color() {

initComponents();

}

@SuppressWarnings("unchecked")

// <editor-fold defaultstate="collapsed" desc="Generated Code">

private void initComponents() {

jColorChooser1 = new javaxswingJColorChooser();

setDefaultCloseOperation(javaxswingWindowConstantsEXIT_ON_CLOSE);

orgjdesktoplayoutGroupLayout layout = new orgjdesktoplayoutGroupLayout(getContentPane());

getContentPane()setLayout(layout);

layoutsetHorizontalGroup(

layoutcreateParallelGroup(orgjdesktoplayoutGroupLayoutLEADING)

add(layoutcreateSequentialGroup()

addContainerGap()

add(jColorChooser1, orgjdesktoplayoutGroupLayoutPREFERRED_SIZE, orgjdesktoplayoutGroupLayoutDEFAULT_SIZE, orgjdesktoplayoutGroupLayoutPREFERRED_SIZE)

addContainerGap(orgjdesktoplayoutGroupLayoutDEFAULT_SIZE, ShortMAX_VALUE))

);

layoutsetVerticalGroup(

layoutcreateParallelGroup(orgjdesktoplayoutGroupLayoutLEADING)

add(layoutcreateSequentialGroup()

add(jColorChooser1, orgjdesktoplayoutGroupLayoutPREFERRED_SIZE, orgjdesktoplayoutGroupLayoutDEFAULT_SIZE, orgjdesktoplayoutGroupLayoutPREFERRED_SIZE)

addContainerGap(46, ShortMAX_VALUE))

);

pack();

}// </editor-fold>

public static void main(String args[]) {

javaawtEventQueueinvokeLater(new Runnable() {

public void run() {

new Color()setVisible(true);

}

});

}

// Variables declaration - do not modify

private javaxswingJColorChooser jColorChooser1;

// End of variables declaration

}

本来是在drawcomponent这个里边使用setBackground，你想啊drawcomponent是继承JComponent的所以它是一个容器，所以它同样有setBackground这个方法来设置它的背景颜色

但是因为你在设置它本身为一个画布，因为你用了paintComponent(Graphics g)

这个方法，所以setBackground这个方法即使你用了也看不到很大的效果。但是有一种取代的方法就是在paintComponent(Graphics g)方法中首先就用Graphics 所含有的方法gsetColor(Colorblack);来设置背景颜色再用gfillRect(0, 0, thisgetWidth(), thisgetHeight());来填满整个容器，这就达到了设置背景目的。然后你再gsetColor(其他颜色);来绘制其它图形

具体代码:(在你以上的代码上修改了点)

public void paintComponent(Graphics g)

{

Graphics2D g2=(Graphics2D)g;

gsetColor(Colorblack);//这里设置背景颜色

gfillRect(0, 0, thisgetWidth(), thisgetHeight());//这里填充背景颜色

double x=100;

double y=100;

double w=200;

double h=150;

Rectangle2D rect=new Rectangle2DDouble(x,y,w,h);

g2setPaint(Colorwhite);//这里是你设置其他笔触颜色

g2draw(rect);

Ellipse2D ellipse=new Ellipse2DDouble();

ellipsesetFrame(rect);

g2draw(ellipse);

Point2D p1=new Point2DDouble(x-40,y-30);

Point2D p2=new Point2DDouble(x+w+40,y+h+30);

g2draw(new Line2DDouble(p1,p2));

double centerx=rectgetCenterX();

double centery=rectgetCenterY();

double radius=150;

Ellipse2D circle=new Ellipse2DDouble();

circlesetFrameFromCenter(centerx,centery,centerx+125,centery+125);

g2draw(circle);

}

测试结果图

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