J2ME常用功能代码片断

原创

曹观沧海 2023-02-08 09:31:17 ©著作权

文章标签 j2me primitive image null immutable 文章分类 Python 后端开发

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1：IO读写

因为J2ME只支持有限的几个IO类，要用这几个类满足自己的需求确实不容易。

try
     {
            InputStream is = new Object().getClass().getResourceAsStream("/52.txt");
            ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
            byte[] bytes = new byte[128];
            int size;
            while( (size = is.read(bytes)) != -1 ){
                 baos.write(bytes, 0, size);
            }
           data = baos.toByteArray();
           iSize = data.length;
           contentCan = new contentCanvas(new String(data));
           is.close();
           is = null;
           baos.close();
           baos = null;
     }
     catch (Exception e)
     {
          e.printStackTrace();
     }

2：字符串转换成整数或其它primitive类型

image_1_num = Integer.parseInt(str3.substring(0,str3.indexOf("-")));
  image_2_num = Integer.parseInt(str3.substring(str3.indexOf("-")+1));

用了无数次了，但每次还是忘记。

3：ChoiceGroup的一个小问题

看API文档

public ChoiceGroup(String label, int choiceType, String[] stringElements, Image[] imageElements)

Creates a new ChoiceGroup, specifying its title, the type of the

ChoiceGroup, and an array of

Strings and

Images to be used as its initial contents.

The type must be one of EXCLUSIVE, MULTIPLE, or POPUP. The IMPLICIT type is not allowed for ChoiceGroup.

The stringElements array must be non-null and every array element must also be non-null. The length of the stringElements array determines the number of elements in the ChoiceGroup. The imageElements array may be null to indicate that the ChoiceGroup elements have no images. If the imageElements array is non-null, it must be the same length as the stringElements array. Individual elements of the imageElements array may be null in order to indicate the absence of an image for the corresponding ChoiceGroup element. Non-null elements of the imageElements array may refer to mutable or immutable images.