将数组从一个类中的ArrayList获取到另一个类

时间:2016-03-07 20:17:58

标签: java swing user-interface arraylist

所以我试图将存储在一个类Liquor的ArrayList中的数据显示到另一个类Bar中。 ArrayList保存5个字符串(酒的名称)和5个整数(每种酒的量)。当我运行代码来显示信息时,我得到一个很长的错误:

  

线程“AWT-EventQueue-0”中的异常java.lang.NullPointerException     at barinventory.BarInv.jButtonDisplayActionPerformed(BarInv.java:355)     at barinventory.BarInv.access $ 200(BarInv.java:8)at   barinventory.BarInv $​​ 3.actionPerformed(BarInv.java:219)at   javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)     在   javax.swing.AbstractButton中的$ Handler.actionPerformed(AbstractButton.java:2348)     在   javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)     在   javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)     在   javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)     在java.awt.Component.processMouseEvent(Component.java:6535)at   javax.swing.JComponent.processMouseEvent(JComponent.java:3324)at   java.awt.Component.processEvent(Component.java:6300)at   java.awt.Container.processEvent(Container.java:2236)at   java.awt.Component.dispatchEventImpl(Component.java:4891)at   java.awt.Container.dispatchEventImpl(Container.java:2294)at   java.awt.Component.dispatchEvent(Component.java:4713)at   java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)     在   java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)     at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)     在java.awt.Container.dispatchEventImpl(Container.java:2280)at   java.awt.Window.dispatchEventImpl(Window.java:2750)at   java.awt.Component.dispatchEvent(Component.java:4713)at   java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)at at   java.awt.EventQueue.access $ 500(EventQueue.java:97)at   java.awt.EventQueue $ 3.run(EventQueue.java:709)at   java.awt.EventQueue $ 3.run(EventQueue.java:703)at   java.security.AccessController.doPrivileged(Native Method)at   java.security.ProtectionDomain $ JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)     在   java.security.ProtectionDomain $ JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)     在java.awt.EventQueue $ 4.run(EventQueue.java:731)at   java.awt.EventQueue $ 4.run(EventQueue.java:729)at   java.security.AccessController.doPrivileged(Native Method)at   java.security.ProtectionDomain $ JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)     在java.awt.EventQueue.dispatchEvent(EventQueue.java:728)at   java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)     在   java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)     在   java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)     在   java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)     在   java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)     at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)   BUILD STOPPED(总时间:12秒)

我的酒类:

final class Liquor
{
    //String[] liquor = {"Vodka", "Whiskey", "Rum", "Gin", "Brandy"};
    private final String vodka, whiskey, rum, gin, brandy;
    private final int vCount, wCount, rCount, gCount, bCount;
    ArrayList<Liquor> liquors = new ArrayList<>();

//    public Liquor(ArrayList<Liquor> liquors)
//    {
//        
//        this.vodka = "Vodka";
//        this.whiskey = "Whiskey";
//        this.rum = "Rum";
//        this.gin = "Gin";
//        this.brandy = "Brandy";
//        this.vCount = getVC();
//        this.wCount = getWC();
//        this.rCount = getRC();
//        this.gCount = getGC();
//        this.bCount = getBC();
//    } was trying to pass it through the ArrayList itself... Didn't work.
      //The stock number kept being read in as 0.



    public Liquor(String vodka, String whiskey, String rum, String gin, 
            String brandy, int v, int w, int r, int g, int b)
    {
        this.vodka = vodka;
        this.whiskey = whiskey;
        this.rum = rum;
        this.gin = gin;
        this.brandy = brandy;
        this.vCount = v;
        this.wCount = w;
        this.rCount = r;
        this.gCount = g;
        this.bCount = b;
    }

    public String getV()
    {
        return vodka;
    }

    public String getW()
    {
        return whiskey;
    }

    public String getR()
    {
        return rum;
    }

    public String getG()
    {
        return gin;
    }

    public String getB()
    {
        return brandy;
    }

    public int getVC()
    {
        return vCount;
    }

    public int getWC()
    {
        return wCount;
    }

    public int getRC()
    {
        return rCount;
    }

    public int getGC()
    {
        return gCount;
    }

    public int getBC()
    {
        return bCount;
    }

    @Override
    public String toString()
    {
        return "\nLiquor currently in stock:\n" + vodka + ": " + vCount + "\n" +
                whiskey + ": " + wCount + "\n" + rum + ": " + rCount + "\n" +
                gin + ": " + gCount + "\n" + brandy + ": " + bCount;
    }
}

我的酒吧课程:

class Bar
{
    private final String barLoc, barName;
    private final boolean music, food;
    //ArrayList<Liquor> liquor;

    public Bar(String l, String n, boolean m, boolean f)
    {
        this.barLoc = l;
        this.barName = n;
        this.music = m;
        this.food = f;
    }

    //ArrayList<Liquor> liquor = new ArrayList<>();
    private Liquor liquor;

    public Liquor getLiquor()
    {
        return liquor;
    }

    @Override
    public String toString()
    {
        return "The " + barLoc + " bar is named: " + barName + "\nLive music: " 
                + music + "\nFood Service: " + food;
    } 
}

用于显示的代码:

for(int i=0; i<bars.size(); i++)
        {
            jTextAreaDisplay.append(jTextAreaDisplay.getText() 
                    + bars.get(i).toString() + bars.get(i).getLiquor().toString() 
                    + "\n\n");

        }

我认为这个问题与初始化我的Bar类中的private Liquor liquor;有关,我已经尝试过不同的方法。但是地图册无法做到正确。任何帮助将不胜感激!

示例运行:

  

(barLocation)栏名为:(barName)

     

现场音乐:(真或假)

     

食品服务:(真或假)

     

现有的白酒:

     伏特加:(库存量)

     

威士忌:(库存量)

     

朗姆酒:(库存量)

     杜松子酒:(库存量)

     

白兰地:(库存量)

2 个答案:

答案 0 :(得分:0)

据我所见,你从来没有初始化酒。

初始化看起来像这样

Liquor liquor = new Liquor("data", "data", ...);

我没有达到创造一个含有更多液体(伏特加等)的单一酒对象的目的。但也许你有理由。 如果没有,那么我会设计不同的酒,因为你所做的并不像现实。 通常情况下,酒类应该具有这样的属性:

public String name;
public double alcohol;

然后我会在你的栏中创建一个Liquors的ArrayList并用一些值填充它。

ArrayList<Liquor> liquors = new ArrayList<Liquor>();
//Fill with something like 4 liquors i call them vodka 0, 1, 2 and 3 and fill them with the alcohol value of 40
for(int i = 0; i < 4; i++){
  liquors.add(new Liquor("Wodka"+i, 40));
}

现在我的fill方法显然要求你的Liquid类有一个带2个参数的构造函数(String name,int alcohol)

答案 1 :(得分:0)

您尚未初始化Liquor对象。请尝试以下语句

private Liquor liquor=new Liquor("vodka",""...,1,2,..);