英文:
Why do i get an an error on paint method when the parameters are correct?
问题
import javax.swing.*;
import java.awt.*;
class Main extends JFrame {
class App extends JPanel {
Stage stage;
public App() {
setPreferredSize(new Dimension(900, 720));
stage = new Stage();
}
@Override
public void paint(Graphics g) {
stage.paint(g, getMousePosition());
}
}
public static void main(String[] args) throws Exception {
Main window = new Main();
window.run();
}
private Main() {
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
App canvas = new App();
this.setContentPane(canvas);
this.pack();
this.setVisible(true);
}
public void run() {
while (true) {
this.repaint();
}
}
}
import java.awt.*;
import java.util.Random;
public class Stage {
Grid grid;
Terrain sand;
Terrain oasis;
Terrain palm_tree;
Terrain wall;
Random RandomNo = new Random();
int number;
public Stage() {
grid = new Grid();
for (int i = 0; i < 20; i++) {
for (int j = 0; j < 20; j++) {
number = 1 + RandomNo.nextInt(10);
if (number <= 4) {
sand = new Sand(grid.cellAtColRow(i, j));
} else if (number == 1) {
oasis = new Oasis(grid.cellAtColRow(i, j));
} else if (number == 2) {
wall = new Wall(grid.cellAtColRow(i, j));
} else if (number == 3) {
palm_tree = new PalmTree(grid.cellAtColRow(i, j));
}
}
}
}
public void paint(Graphics g, Point mouseLoc) {
grid.paint(g, mouseLoc);
sand.paint(g);
oasis.paint(g);
wall.paint(g);
palm_tree.paint(g);
}
}
import java.awt.*;
class Grid {
//fields
Cell[][] cells = new Cell[20][20];
// constructor
public Grid() {
for (int i = 0; i < cells.length; i++) {
for (int j = 0; j < cells[i].length; j++) {
cells[i][j] = new Cell(10 + 35 * i, 10 + 35 * j);
}
}
}
// methods
public void paint(Graphics g, Point mousePos) {
for (int i = 0; i < cells.length; i++) {
for (int j = 0; j < cells[i].length; j++) {
cells[i][j].paint(g, mousePos);
}
}
}
public Cell cellAtColRow(int c, int r) {
return cells[c][r];
}
}
import java.awt.*;
class Cell extends Rectangle {
// fields
static int size = 35;
//constructors
public Cell(int x, int y) {
super(x, y, size, size);
}
//methods
void paint(Graphics g, Point mousePos) {
if (contains(mousePos)) {
g.setColor(Color.GRAY);
} else {
g.setColor(Color.WHITE);
}
g.fillRect(x, y, size, size);
g.setColor(Color.BLACK);
g.drawRect(x, y, size, size);
}
public boolean contains(Point p) {
if (p != null) {
return super.contains(p);
} else {
return false;
}
}
}
英文:
I am facing an issue with the paint method in the below program. The error "void Stage.paint(Graphic g, Point mouseloc)" and the error "paint cannot be resolved to a type". I have inputted the correct parameters and have set the fields and constructors properly. The error are in italics.Sorry i am new to coding and hopefully you can help me
import javax.swing.*;
import java.awt.*;
class Main extends JFrame {
class App extends JPanel {
Stage stage;
public App() {
setPreferredSize(new Dimension(900, 720));
stage = new Stage();
}
@Override
public void paint(Graphics g) {
*stage.paint(g, getMousePosition());*
}
}
public static void main(String[] args) throws Exception {
Main window = new Main();
window.run();
}
private Main() {
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
App canvas = new App();
this.setContentPane(canvas);
this.pack();
this.setVisible(true);
}
public void run() {
while (true) {
this.repaint();
}
}
}
import java.awt.*;
import java.util.Random;
public class Stage {
Grid grid;
Terrain sand;
Terrain oasis;
Terrain palm_tree;
Terrain wall;
Random RandomNo = new Random();
int number;
public Stage() {
grid = new Grid();
for(int i = 0;i<20;i++)
{
for (int j = 0; j < 20; j++) {
number = 1 + RandomNo.nextInt(10);
if (number <= 4) {
sand = new Sand(grid.cellAtColRow(i, j));
} else if (number == 1) {
oasis = new Oasis(grid.cellAtColRow(i, j));
} else if (number == 2) {
wall = new Wall(grid.cellAtColRow(i, j));
} else if (number == 3) {
palm_tree = new PalmTree(grid.cellAtColRow(i, j));
}
}
}
*public paint(Graphics g, Point mouseLoc){*
grid.paint(g, mouseLoc);
sand.paint(g);
oasis.paint(g);
wall.paint(g);
palm_tree.paint(g);
}
}
}
import java.awt.*;
class Grid {
//fields
Cell[][] cells = new Cell[20][20];
// constructor
public Grid(){
for(int i = 0; i < cells.length; i++){
for(int j = 0; j < cells[i].length; j++){
cells[i][j] = new Cell(10+35*i,10+35*j);
}
}
}
// methods
public void paint(Graphics g, Point mousePos){
for(int i = 0; i < cells.length; i++){
for(int j = 0; j < cells[i].length; j++){
cells[i][j].paint(g, mousePos);
}
}
}
public Cell cellAtColRow(int c, int r){
return cells[c][r];
}
}
import java.awt.*;
class Cell extends Rectangle {
// fields
static int size = 35;
//constructors
public Cell(int x, int y){
super(x,y,size,size);
}
//methods
void paint(Graphics g, Point mousePos){
if(contains(mousePos)){
g.setColor(Color.GRAY);
}
else {
g.setColor(Color.WHITE);
}
g.fillRect(x,y,size,size);
g.setColor(Color.BLACK);
g.drawRect(x,y,size,size);
}
public boolean contains(Point p){
if (p != null){
return super.contains(p);
} else {
return false;
}
}
}
答案1
得分: 0
第一个问题...
首先，public paint(Graphics g, Point mouseLoc){ 不是一个有效的声明，你缺少了返回类型。
应该是 public void paint(Graphics g, Point mouseLoc) {
第二个问题，你有一个放置错误的 }，这意味着 paint 实际上被声明在构造函数内部...
public Stage() {
grid = new Grid();
for(int i = 0;i<20;i++)
{
for (int j = 0; j < 20; j++) {
number = 1 + RandomNo.nextInt(10);
if (number <= 4) {
sand = new Sand(grid.cellAtColRow(i, j));
} else if (number == 1) {
oasis = new Oasis(grid.cellAtColRow(i, j));
} else if (number == 2) {
wall = new Wall(grid.cellAtColRow(i, j));
} else if (number == 3) {
palm_tree = new PalmTree(grid.cellAtColRow(i, j));
}
}
}
public paint(Graphics g, Point mouseLoc){
grid.paint(g, mouseLoc);
sand.paint(g);
oasis.paint(g);
wall.paint(g);
palm_tree.paint(g);
}
}
应该更像是...
public Stage() {
grid = new Grid();
for(int i = 0;i<20;i++)
{
for (int j = 0; j < 20; j++) {
number = 1 + RandomNo.nextInt(10);
if (number <= 4) {
sand = new Sand(grid.cellAtColRow(i, j));
} else if (number == 1) {
oasis = new Oasis(grid.cellAtColRow(i, j));
} else if (number == 2) {
wall = new Wall(grid.cellAtColRow(i, j));
} else if (number == 3) {
palm_tree = new PalmTree(grid.cellAtColRow(i, j));
}
}
}
}
public void paint(Graphics g, Point mouseLoc){
grid.paint(g, mouseLoc);
sand.paint(g);
oasis.paint(g);
wall.paint(g);
palm_tree.paint(g);
}
英文:
Two problems...
First public paint(Graphics g, Point mouseLoc){ is not a valid declaration, you're missing the return type.
It should be public void paint(Graphics g, Point mouseLoc) {
Second, you have a misplaced }, which means that paint is actually been declared inside the constructor...
public Stage() {
grid = new Grid();
for(int i = 0;i<20;i++)
{
for (int j = 0; j < 20; j++) {
number = 1 + RandomNo.nextInt(10);
if (number <= 4) {
sand = new Sand(grid.cellAtColRow(i, j));
} else if (number == 1) {
oasis = new Oasis(grid.cellAtColRow(i, j));
} else if (number == 2) {
wall = new Wall(grid.cellAtColRow(i, j));
} else if (number == 3) {
palm_tree = new PalmTree(grid.cellAtColRow(i, j));
}
}
}
public paint(Graphics g, Point mouseLoc){
grid.paint(g, mouseLoc);
sand.paint(g);
oasis.paint(g);
wall.paint(g);
palm_tree.paint(g);
}
}
It should be more like...
public Stage() {
grid = new Grid();
for(int i = 0;i<20;i++)
{
for (int j = 0; j < 20; j++) {
number = 1 + RandomNo.nextInt(10);
if (number <= 4) {
sand = new Sand(grid.cellAtColRow(i, j));
} else if (number == 1) {
oasis = new Oasis(grid.cellAtColRow(i, j));
} else if (number == 2) {
wall = new Wall(grid.cellAtColRow(i, j));
} else if (number == 3) {
palm_tree = new PalmTree(grid.cellAtColRow(i, j));
}
}
}
}
public void paint(Graphics g, Point mouseLoc){
grid.paint(g, mouseLoc);
sand.paint(g);
oasis.paint(g);
wall.paint(g);
palm_tree.paint(g);
}
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