以下代码会报 空指针异常,高手帮忙看下我就是想把自定义的一个类的对象存到一个ArrayList里面,然后需要的时候读出来把以下所有代码放在一个.java 文件里就可以了,
import java.util.ArrayList;
import java.awt.*;
public class Bullet {
public static void main(String[] args)
{
Bullet bullet = new Bullet();
bullet.drawMe();
}
private ArrayList<bulletInfo> bulletArray = new ArrayList<bulletInfo>(); //网上看别人的类似问题
//private ArrayList<bulletInfo> bulletArray =null;会报空指针异常,可是我
//没有这样写 public Bullet(){
int x=1,y=2,z=3;
bulletArray.add(new bulletInfo(x,y,z)); //是不是这个add出问题??
}
public void drawMe(){
for(int i = 0;i < bulletArray.size();i++)
{
System.out.println(bulletArray.get(i).getBulletPosition().x);
}
}
}class bulletInfo {
private Point bulletLocate;
private int selfDirection ;
public bulletInfo(int a,int b,int direction){
this.selfDirection = direction;
this.bulletLocate.x = a;
this.bulletLocate.y = b;
}
public Point getBulletPosition(){
return bulletLocate;
}
public int getBulletDirection(){
return selfDirection;
}}
import java.util.ArrayList;
import java.awt.*;
public class Bullet {
public static void main(String[] args)
{
Bullet bullet = new Bullet();
bullet.drawMe();
}
private ArrayList<bulletInfo> bulletArray = new ArrayList<bulletInfo>(); //网上看别人的类似问题
//private ArrayList<bulletInfo> bulletArray =null;会报空指针异常,可是我
//没有这样写 public Bullet(){
int x=1,y=2,z=3;
bulletArray.add(new bulletInfo(x,y,z)); //是不是这个add出问题??
}
public void drawMe(){
for(int i = 0;i < bulletArray.size();i++)
{
System.out.println(bulletArray.get(i).getBulletPosition().x);
}
}
}class bulletInfo {
private Point bulletLocate;
private int selfDirection ;
public bulletInfo(int a,int b,int direction){
this.selfDirection = direction;
this.bulletLocate.x = a;
this.bulletLocate.y = b;
}
public Point getBulletPosition(){
return bulletLocate;
}
public int getBulletDirection(){
return selfDirection;
}}
import java.util.ArrayList;
import java.awt.*;public class Bullet {
public static void main(String[] args) {
Bullet bullet = new Bullet();
bullet.drawMe();
} private ArrayList<bulletInfo> bulletArray = new ArrayList<bulletInfo>(); // 网上看别人的类似问题 // private ArrayList <bulletInfo> bulletArray =null;会报空指针异常,可是我
// 没有这样写 public Bullet() { int x = 1, y = 2, z = 3; bulletArray.add(new bulletInfo(x, y, z)); // 是不是这个add出问题??
} public void drawMe() { for (int i = 0; i < bulletArray.size(); i++) {
System.out.println(bulletArray.get(i).getBulletPosition().x); }
}
}class bulletInfo { private Point bulletLocate=new Point();
private int selfDirection; public bulletInfo(int a, int b, int direction) { this.selfDirection = direction;
this.bulletLocate.x = a;
this.bulletLocate.y = b; } public Point getBulletPosition() {
return bulletLocate;
} public int getBulletDirection() {
return selfDirection;
}}
this.bulletLocate.x = a;
this.bulletLocate.y = b;
前面加上:
this.bulletLocate = new Point();