如果不声明在Java中正确评估布尔？ [英] if Statement not evaluating boolean correctly in Java?
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问题描述
我做一个简单的游戏，你在屏幕上移动球，并尽量避免在屏幕上的其它块。
I'm making a simple game where you move a ball on a screen and try to avoid other blocks on the screen.
我遇到的问题是，当我尝试评估你是否接触到另一个块，我的if语句总是返回的第一个结果不管是什么我布尔等于。
这里是我评价该语句的方法
The problem i'm having is that when I try to evaluate whether you are touching another block, my if statement always returns the first result no matter what my boolean equals. Here is the method where I evaluate the statement
public void actionPerformed(ActionEvent evt) {
//Move the ball
myY = myY - 5;
if(myY < 0){
myY = 0;
}
//test if it is intersecting
boolean sect = testIntersection(r, playa);
System.out.println(sect);
if(sect = true){
cir = Color.BLACK;
System.out.println("Intersected");
}else{
cir = Color.RED;
}
playa.setFrame(myX, myY, 30,30);
repaint();
}
下面是code那发送的教派的布尔的部分：
Here is the section of code that sends the sect Boolean:
public static boolean testIntersection(Shape shapeA, Shape shapeB) {
Area areaA = new Area(shapeA);
areaA.intersect(new Area(shapeB));
return !areaA.isEmpty();
}
下面是整个code：
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import javax.swing.JFrame;
import javax.swing.Timer;
import java.lang.Object;
public class moving extends Canvas implements ActionListener{
Timer up = new Timer(10, this);
Timer down = new Timer(10, this);
Timer left = new Timer(10, this);
Timer right = new Timer(10, this);
int sected;
int myX = 400;
int myY = 400;
Ellipse2D playa = new Ellipse2D.Double(myX, myY, 30, 30);
Rectangle r = new Rectangle(20,33,20, 100);
boolean sect = testIntersection(r, playa);
Color cir = new Color(0,0,0);
public moving() {
setSize(new Dimension(500, 500));
final int width = getWidth();
final int height = getHeight();
up.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
myY = myY - 5;
if(myY < 0){
myY = 0;
}
boolean sect = testIntersection(r, playa);
System.out.println(sect);
if(sect = true){
System.out.println("intersected!!!!!1");
}else{
cir = Color.RED;
}
playa.setFrame(myX, myY, 30,30);
repaint();
}
});
down.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
myY = myY + 5;
if(myY > height - 30){
myY = height - 30;
}
boolean sect = testIntersection(r, playa);
System.out.println(sect);
if(sect = true){
System.out.println("intersected");
}else{
cir = Color.RED;
}
playa.setFrame(myX, myY, 30,30);
repaint();
}
});
left.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
myX = myX - 5;
if(myX < 0){
myX = 0;
}
boolean sect = testIntersection(r, playa);
System.out.println(sect);
if(sect = true){
System.out.println("intersected");
}else{
cir = Color.RED;
}
playa.setFrame(myX, myY, 30,30);
repaint();
}
});
right.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
myX = myX + 5;
if(myX > width - 30){
myX = width - 30;
}
boolean sect = testIntersection(r, playa);
System.out.println(sect);
if(sect = true){
System.out.println("intersected");
}else{
cir = Color.RED;
}
playa.setFrame(myX, myY, 30,30);
repaint();
}
});
addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent evt) {
moveIt(evt);
}
public void keyReleased(KeyEvent evt) {
NomoveIt(evt);
}
});
}
public void moveIt(KeyEvent evt) {
switch (evt.getKeyCode()) {
case KeyEvent.VK_DOWN:
down.start();
break;
case KeyEvent.VK_UP:
up.start();
break;
case KeyEvent.VK_LEFT:
left.start();
break;
case KeyEvent.VK_RIGHT:
right.start();
break;
}
repaint();
}
public void NomoveIt(KeyEvent evt) {
switch (evt.getKeyCode()) {
case KeyEvent.VK_DOWN:
down.stop();
break;
case KeyEvent.VK_UP:
up.stop();
break;
case KeyEvent.VK_LEFT:
left.stop();
break;
case KeyEvent.VK_RIGHT:
right.stop();
break;
}
repaint();
}
public static void main(String[] args) {
JFrame frame = new JFrame("Basic Game");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
moving ex = new moving();
frame.getContentPane().add(ex);
frame.pack();
frame.setResizable(false);
frame.setVisible(true);
ex.requestFocus();
}
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
if(sect = true){
g.setColor(cir);
}else{
g.setColor(cir);
}
g2.fill(playa);
g.setColor(Color.black);
g2.fill(r);
}
public static boolean testIntersection(Shape shapeA, Shape shapeB) {
Area areaA = new Area(shapeA);
areaA.intersect(new Area(shapeB));
return !areaA.isEmpty();
}
请告诉我，我在做什么错在这里！
Please tell me what I am doing wrong here!!!
谢谢！
推荐答案
您需要
if (sect == true) { // compares sect with true and checks the result
而不是
if (sect = true) { // sets sect to true and then checks it
即使更好是使用
if (sect) { // checks sect
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