从另一个方法获取String [英] Get String from another method

问题描述

我有2个方法，第一个显示所选值的方法，来自我的JList（列表）的索引。我想要做的是将selectedValue - s - 发送到CreateMap方法。我试过这段代码，但是s变量是null。为什么？

I have 2 methods, the first one where i display selected value, index from my JList(list). What i want to do is to send selectedValue - s - to CreateMap method. I tried this code, but s variable is null. Why?

public void actionPerformed(ActionEvent e)
    {
        int index = 0;

        if(e.getActionCommand().equals("Check")){ //if button is pressed

            index = list.getSelectedIndex();
            System.out.println("Index selected" + index);
            String s = (String) list.getSelectedValue();
            System.out.println("Value Selected " +s);

            createMap();

    }

}


     private Map<String, Integer>createMap()
     {
         Map<String, Integer> graphicsMap = new HashMap<>();

         for(LaneInformation l:graphics.laneInfos )
         {
             if (l.getEllipse().contains(graphics.startX, graphics.startY)) {
                 graphicsMap.put(this.s, graphics.startX);


             }

         }

         return graphicsMap;     
     }

推荐答案

我假设你有2个字符串变量名为 s ，一个全局变量和一个本地变量 actionPerformed 。

I assume you have 2 String variables called s, one global and one local in actionPerformed.

更改行

String s = (String) list.getSelectedValue();

到

this.s = (String) list.getSelectedValue();

它应该有效。确保你有一个名为 String s 的全局变量。

And it should work. Be sure you have a global variable called String s.

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