我一直在試圖爲我的遊戲做一家商店。 這是不成功的。如何在使用Graphics2D嘗試在JPanel上呈現時如何解決此NullPointerException?
我試過drawComponent,沒有工作。 沒有錯誤,代碼執行,但沒有奏效。 現在我想要做的事:
private void render() {
Graphics2D g = (Graphics2D) graphics.getGraphics();
/////////////////////
g.drawImage(img, 0, 0, WIDTH, HEIGHT, null);
/////////////////////
g.dispose();
Graphics2D g2d = (Graphics2D) getGraphics();
g2d.drawImage(img, 0, 0, null);
g2d.dispose();
}
現在我得到G2D一個NullPointerException。 我試過了一切。
`Exception in thread "game" java.lang.NullPointerException
at com.johnythecarrot.game.Shop$DrawPane.access$2(Shop.java:123)
at com.johnythecarrot.game.Shop.render(Shop.java:154)
at com.johnythecarrot.game.Game.render(Game.java:75)
at com.johnythecarrot.game.Game.run(Game.java:112)
at java.lang.Thread.run(Unknown Source)`
我的目標是能夠有可點擊的按鈕。 它是DID的工作。但我幾乎每次都必須重新啓動。因爲大部分時間代碼甚至沒有執行。所以我試圖修復它。現在全都搞砸了。
這是它的代碼。 (DoubleInt是我的媒體庫的一部分,它無非只是X和Y更多。)
public class Shop {
public BuildWindow window;
public static JWindow w;
private int WIDTH = 860, HEIGHT = 440;
private BufferedImage graphics = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
public DrawPane drawPane;
public Shop() {
//window = new BuildWindow().setSize(new DoubleInt(100, 100)).at(wi, he).setTitle("Shop").setOpacity(1).setDragable(false).showEmpty(true);
w = new JWindow();
w.setOpacity(1);
w.setSize(WIDTH, HEIGHT);
w.setLocation(800, 800);
w.setVisible(false);
w.setAlwaysOnTop(true);
//graphics = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
}
private void createShop() {
/***Graphics2D g = (Graphics2D) graphics.getGraphics();
g.setColor(Color.blue);
g.drawString("hey", WIDTH-50, HEIGHT-50);
g.fillRect(0, 0, WIDTH, HEIGHT);*/
}
public class DrawPane extends JPanel {
int width = WIDTH;
int height = HEIGHT;
private ArrayList<Shape> buttons;
private Shape btn1 = new Rectangle2D.Double(20, 60, width/2, height-20);
private Shape btnClose = new Rectangle2D.Double(width-25, 5, 20, 20);
Point wCoords;
Point mCoords;
public DrawPane() {
buttons = new ArrayList<>();
buttons.add(btn1);
buttons.add(btnClose);
addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
super.mouseClicked(e);
for(Shape s : buttons) {
if(s.contains(e.getPoint())) {
System.out.println("Clicked " + s.getBounds());
if(s == btnClose) {
w.dispose();
}
}
}
}
@Override
public void mousePressed(MouseEvent e) {
mCoords = e.getPoint();
}
@Override
public void mouseReleased(MouseEvent arg0) {
mCoords = null;
}
});
addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent e) {
wCoords = e.getLocationOnScreen();
w.setLocation(wCoords.x - mCoords.x, wCoords.y - mCoords.y);
}
});
}
void repaintThis() {
repaint();
}
BufferedImage img = loadImageFrom.LoadImageFrom(Shop.class, "bar.png");
Graphics gb;
/**
* super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g.setColor(Color.red);
//g.fillRect(0, 0, width, 50);
g.drawImage(img, 0, 0, width, 50, null);
g.setColor(Color.WHITE);
g.drawString("SHOP", 15, 30);
g.drawString("X", width-20, 20);
for(Shape b : buttons) {
g2d.draw(b);
}
System.out.println("Built");
gb = g;
*/
private void render() {
Graphics2D g = (Graphics2D) graphics.getGraphics();
/////////////////////
g.drawImage(img, 0, 0, WIDTH, HEIGHT, null);
/////////////////////
g.dispose();
Graphics2D g2d = (Graphics2D) getGraphics();
g2d.drawImage(img, 0, 0, null);
g2d.dispose();
}
public void Build() {
Graphics g = gb;
Graphics2D g2d = (Graphics2D) g;
g.setColor(Color.red);
//g.fillRect(0, 0, width, 50);
g.drawImage(img, 0, 0, width, 50, null);
g.setColor(Color.WHITE);
g.drawString("SHOP", 15, 30);
g.drawString("X", width-20, 20);
for(Shape b : buttons) {
g2d.draw(b);
}
System.out.println("Built");
}
}
public void render(Graphics2D g) {
drawPane.render();
}
public void addDrawPane() {
drawPane = new DrawPane();
w.add(drawPane);
}
}
如果您需要獲得更多的代碼,只是問我。
看起來'grahpics'是'null' –
不應該'g'是'Graphics'對象嗎? –
使用paintComponent()的代碼更新你的問題好嗎? –