1. 程式人生 > >java將集合轉換為陣列(二維陣列)

java將集合轉換為陣列(二維陣列)

public class ListToArray {
    /**
     * 獲取物件屬性,返回一個字串陣列
     * 
     * @param o 物件
     * @return String[] 字串陣列
     */
    private String[] getFiledName(Object o) {
        try {
            Field[] fields = o.getClass().getDeclaredFields();
            String[] fieldNames = new String[fields.length];
            for (int i = 0; i < fields.length; i++) {
                fieldNames[i] = fields[i].getName();
            }
            return fieldNames;
        } catch (SecurityException e) {
            e.printStackTrace();
            System.out.println(e.toString());
        }
        return null;
    }

    
    /**
     * 使用反射根據屬性名稱獲取t屬性的get方法
     * 
     * @param fieldName 屬性名稱
     * @param o 操作物件
     * @return List<Method> get方法
     */
    
    private List<Method> getGetField(String[] fieldNames, Object o) {
       
            List<Method> methods=new ArrayList<Method>();
            for (String fieldName : fieldNames) {
                String firstLetter = fieldName.substring(0, 1).toUpperCase();
                String getter = "get" + firstLetter + fieldName.substring(1);
                Method method = null;
                try {
                    method = o.getClass().getMethod(getter, new Class[] {});
                } catch (NoSuchMethodException e) {
                    System.out.println("屬性不存在");
                    continue;
                }
                //Object value = method.invoke(o, new Object[] {});
                methods.add(method);
            }
            return methods;
        
    }
    /**
     * 將list集合轉換為二維string陣列
     * 
     * @param list 要轉換的集合
     * @return String[][] 返回的sting陣列
     */
    
    public String[][] listToArrayWay(List list) {
        Object o=list.get(0);
        
        String[] filedNames = getFiledName(o);
        int filedNum=filedNames.length;
        int listSize=list.size();
        List<Method> methods=getGetField(filedNames, o);
        
        String[][] arrs=new String[listSize][filedNum];
        int i=0;
        for (Object object : list) {
            int j=0;
            for (Method method : methods) {
                Object value=null;
                try {
                    value = method.invoke(object, new Object[] {});
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    System.out.println("屬性不存在"+e);
                }
                arrs[i][j]=(String) value;
                j++;
            }
            i++;
        }
       
        return arrs;
    }

}