[英]Having trouble making my first subclass in Java
我正在嘗試為我的Java課程制作一個Breakout游戲程序,該程序包含一系列彩色塊(磚)。 我已經成功完成了此任務,但現在我的教練希望我們添加不同的Bricks子類。 他想要的子類之一是ColorBrick,它繼承了Brick超類的所有行為,除了它具有每5個滴答變化一次的顏色數組。 構造函數采用顏色數組,而不是單一顏色。
這是我的Brick超類所擁有的:
package Breakout;
import java.awt.Color;
import java.awt.Graphics;
public class Brick {
public int x, y, i, j;
public Color c;
Brick[][] brick;
public Brick() {
}
public Brick(Color c, Brick[][] brick, int i, int j) {
this.c = c;
this.brick = brick;
this.x = i * 40;
this.y = j * 10 + 50;
this.i = i;
this.j = j;
}
public void tick() {
}
public void paint(Graphics g) {
g.setColor(c);
g.fillRect(x, y, Breakout.brickWidth, Breakout.brickHeight);
}
public void hit(Ball b) {
if (b.yThen > y + Breakout.brickHeight) {
b.yv = -b.yv;
b.yNow = 2 * (y + Breakout.brickHeight) - b.yNow;
}
if (b.yThen < y) {
b.yv = -b.yv;
b.yNow = 2 * (y) - b.yNow;
}
if (b.xThen > x + Breakout.brickWidth) {
b.xv = -b.xv;
b.xNow = 2 * (x + Breakout.brickWidth) - b.xNow;
}
if (b.xThen < x) {
b.xv = -b.xv;
b.xNow = 2 * (x) - b.xNow;
}
brick[i][j] = null;
}
}
到目前為止,這是我的colorBrick子類所擁有的:
package Breakout;
import java.awt.Color;
public class ColorBrick extends Brick {
Color colors[] = {Color.red, Color.green, Color.blue, Color.yellow};
public ColorBrick(Color[] colors, Brick[][] brick, int i, int j){
this.colors = colors;
this.brick = brick;
this.i = i;
this.j = j;
}
public void tick(){
}
}
在這一點上,我碰壁了,我不確定從這里開始該怎么做。 我的教練說,由於某種原因,tick方法在超類中需要為空。 如果需要為空,那他為什么要我們把它放在那里? 我也不確定應該在子類tick方法中添加什么。 我到底是朝着正確的方向前進,還是到目前為止我做的一切完全錯誤? 任何指導將不勝感激!
如果有用,這是我的主要突破代碼:
package Breakout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Breakout extends javax.swing.JFrame {
public static final int fieldHeight = 600;
public static final int fieldWidth = 400;
public int diameter = 5;
public int xNow = 200 - (diameter / 2);
public int yNow = 300 - (diameter - 2);
public int paddleWidth = 50;
public int paddleHeight = 5;
public int platform = 580;
public static int mousex;
public int mousey;
public static int brickWidth = 40;
public static int brickHeight = 10;
public Random randoms = new Random();
Brick[][] bricks = new Brick[arrayWide][arrayHigh];
public static boolean startUp;
public static int arrayWide = 10;
public static int arrayHigh = 5;
Ball ball = new Ball(200 - (diameter / 2), 20 /*300 - (diameter /2)*/, 0, 0, diameter, Color.white);
Paddle myPaddle = new Paddle(platform, paddleWidth, paddleHeight);
/**
* Creates new form Breakout
*/
public Breakout() {
initComponents();
clock.start();
}
public class MyPanel extends JPanel {
@Override
public void paint(Graphics g) {
super.paint(g);
if (startUp) {
ball.paint(g);
}
myPaddle.paint(g);
for (int i = 0; i < arrayWide; i++) {
for (int j = 0; j < arrayHigh; j++) {
if (bricks[i][j] != null) {
bricks[i][j].paint(g);
}
}
}
// Insert code to paint the scene here.
// Use methods in the Graphics class to do the painting
// Remember coordinates use (0,0) at the top left
}
}
public Timer clock = new Timer(50, new ActionListener() { // 50ms delay between ticks
public void actionPerformed(ActionEvent e) {
tick(); // Write a method named tick to advance your game
jPanel1.repaint();
}
}); // panel is the name of the JPanel that displays the game
public void launchball() {
}
public void tick() {
ball.move();
Brick brick2 = brickAt(ball);
if (brick2 != null) {
brick2.hit(ball);
}
myPaddle.move(mousex);
myPaddle.bounce(ball);
System.out.println();
}
public Brick brickAt(Ball b) {
int j = (int) (b.yNow - 50) / 10;
int i = (int) (b.xNow / 40);
if (i < arrayWide && i >= 0 && j < arrayHigh && j >= 0) {
return (bricks[i][j]);
}
return null;
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jPopupMenu1 = new javax.swing.JPopupMenu();
jPanel2 = new javax.swing.JPanel();
jPanel1 = new MyPanel();
jLabel1 = new javax.swing.JLabel();
start = new javax.swing.JButton();
org.jdesktop.layout.GroupLayout jPanel2Layout = new org.jdesktop.layout.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(0, 100, Short.MAX_VALUE)
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(0, 100, Short.MAX_VALUE)
);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jPanel1.setBackground(new java.awt.Color(0, 0, 0));
jPanel1.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
public void mouseMoved(java.awt.event.MouseEvent evt) {
mouseMove(evt);
}
});
org.jdesktop.layout.GroupLayout jPanel1Layout = new org.jdesktop.layout.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(0, 400, Short.MAX_VALUE)
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(0, 600, Short.MAX_VALUE)
);
jLabel1.setFont(new java.awt.Font("Hobo Std", 1, 24)); // NOI18N
jLabel1.setForeground(new java.awt.Color(153, 51, 255));
jLabel1.setText("Breakout");
start.setFont(new java.awt.Font("Hobo Std", 0, 13)); // NOI18N
start.setForeground(new java.awt.Color(255, 51, 0));
start.setText("Start");
start.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
startActionPerformed(evt);
}
});
org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(layout.createSequentialGroup()
.add(layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(layout.createSequentialGroup()
.add(164, 164, 164)
.add(jLabel1))
.add(layout.createSequentialGroup()
.add(15, 15, 15)
.add(jPanel1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))
.add(layout.createSequentialGroup()
.add(175, 175, 175)
.add(start)))
.addContainerGap(17, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
.add(layout.createSequentialGroup()
.add(16, 16, 16)
.add(jLabel1)
.addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED)
.add(jPanel1, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED)
.add(start)
.addContainerGap(10, Short.MAX_VALUE))
);
pack();
}// </editor-fold>
private void mouseMove(java.awt.event.MouseEvent evt) {
mousex = evt.getX();
mousey = evt.getY();
}
private void startActionPerformed(java.awt.event.ActionEvent evt) {
startUp = true;
ball.xNow = 200 - (diameter / 2);
ball.yNow = 300 - (diameter - 2);
ball.xv = 0;
ball.yv = 8;
for (int i = 0; i < arrayWide; i++) {
for (int j = 0; j < arrayHigh; j++) {
if ((j % 2 == 0 && i % 2 == 0) || (j % 2 == 1 && i % 2 == 1)) {
bricks[i][j] = new Brick(Color.magenta, bricks, i, j);
} else {
bricks[i][j] = new Brick(Color.gray, bricks, i, j);
}
}
}
}
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(Breakout.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Breakout.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Breakout.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Breakout.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Breakout().setVisible(true);
}
});
}
由於這聽起來像homework.classwork,所以我不會詳細介紹。
大概,某事(TBD)將每5秒(或定期)調用一次tick()。 普通的Brick
什么都不做。 您的ColorBrick
應該每5秒鍾更改為下一個顏色。 它需要以某種方式知道它的當前顏色,然后更改為下一個。
Brick
需要有一個空的tick
方法,以便另一個類只需要處理Bricks。 調用tick
的類不需要知道它是Brick
還是ColorBrick
。 tick
的行為由運行時類指定; 這是多態性-相關類對同一方法調用做出不同反應的能力。
子類tick
方法需要跟蹤已生成的tick數量。 必要時,它將更改Color變量c
。
我可能要進行的另一項更改是在您的ColorBrick
構造函數中:利用super
調用超類構造函數,以免重復您的代碼。
另外,聲明實例變量( c
, x
, y
等) protected
以便只有類本身和子類才能直接訪問它們。
tick方法需要在超類上存在,因為我想這樣做的目的是針對每個存在的Brick都將調用tick()(可能在主Breakout類中,可能在循環中)。 超類中的tick()方法指定“默認”行為,該行為不執行任何操作。 對於您的ColorBrick類,當調用刻度時,顏色需要每五個刻度更改一次,因此您需要在子類(ColorBrick)中指定這種特殊的行為方式。
為此,ColorBrick需要一種方法來計數tick()被調用的次數。 添加了可以執行此操作的代碼后,您就可以考慮在某些刻度上更改ColorBrick的顏色:您的ColorBrick已經“知道”它的當前顏色,因為它是從Brick擴展而來的,Brick具有Color屬性( c),因此是在某些價格變動時更改該值的情況。
我已經故意離開了這個模糊的地方,因為我不想為您完成任務,但是請隨時提出任何問題。
您需要在ColorBrick
實現您的tick
方法,如下所示:
private int i = 0;
public void tick(){
c = colors[i++ % colors.length];
}
現在,在制作圖形應用程序時,您可以簡單地使用Brick
類來創建ColorBricks
。 例如,添加多塊磚砌成一堵牆:
Brick[][] wall = new Brick[5][5];
上面數組中的某些Brick
可能是ColorBrick
。 這允許為每個Brick
對象具有通用接口,即tick()
方法。 但是對於ColorBrick
此方法實際上會更改Brick
的顏色,就像其他Brick
它什么也不做!
您可以做更多諸如DancingBrick
類的事情,這些事情在每次tick
之后都會改變大小。 您不需要對圖形實現進行徹底的更改即可添加不同種類的Brick
因為它使用的基本類型為Brick
。
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