Question

您好我开发了一个Android应用程序，我从mysql中检索类别并将它们设置为自定义数组列表并将它们显示为按钮。

现在我想从本地sqlite数据库中提取相同的类别并将它们显示为按钮。但在第一种情况下，我创建了一个自定义列表数组，我分配了响应并将项目添加到该列表并显示为按钮。

但是当我试图从本地sqlite数据库中检索它时，我没有得到如何将值添加到数组列表

这就是我从mysql中检索的方式

 @Override
    protected void onPostExecute(String resp) {
        progressDialog.dismiss();
        if(resp ==null) {
            if (categoriesResp != null) {
                //Toast.makeText(getApplicationContext(), ""+categoriesResp, 5000).show();
                updateUi(categoriesResp.response);
            } else
                Toast.makeText(Categories.this, "Something went wrong",   Toast.LENGTH_LONG).show();
        }else

            if(!Utils.isNetConnected(Categories.this))
                Utils.showDialog(Categories.this);
            else
            Toast.makeText(Categories.this, resp, Toast.LENGTH_LONG).show();

    }
}

这是我的Uiupdate（）方法

    private void Uiupdate(List<Category> response) {
    int i = 0;
    for(Category category:response){
        LayoutInflater inflater = getLayoutInflater();
        View row = inflater.inflate(R.layout.my_category, null, false);
        Button button = (Button) row.findViewById(R.id.buttonCategory);
        button.setText(category.CategoryName);
        button.setTag(category.CategoryID);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(Utils.isNetConnected(Categories.this)) {
                    Intent intent = new Intent(Categories.this, MainActivity.class);
                    intent.putExtra("categoryId", (String) v.getTag());
                    intent.putExtra("categoryName", ((Button) v).getText());

                    startActivity(intent);
                }else
                    Utils.showDialog(Categories.this);
            }
        });
        if(i%2 == 0)
            button.setBackgroundResource(R.drawable.label_with_arrow);
        else
            button.setBackgroundResource(R.drawable.field_with_arrow);
        i++;
        categoriesContainer.addView(row);
    }

}

这是我的本地sqlite方法

 public void loadCategories()
{
    Toast.makeText(getApplicationContext(), "Loaded", 5000).show();
    db = this.openOrCreateDatabase("tafrider", MODE_PRIVATE, null);
    c = db.rawQuery("SELECT CategoryID,CategoryName FROM categories WHERE EventID= 0  and status= 1 ",null);
    List<Category> categories = new ArrayList<Category>();
    while(c.moveToNext()){ 
       categoryName = c.getString(c.getColumnIndex("CategoryName"));

       Category c1 = new Category();
       c1.CategoryName= categoryName;
       Category.add(c1);
       // Toast.makeText(getApplicationContext(), ""+categoryName, 5000).show();

    } 
    Toast.makeText(getApplicationContext(), ""+categories.size(), 5000).show();
    updateUi(categories);

}

在这里，我面临category.add（categoryName）显示错误的问题怎么解决这个问题..？

Answer 1

就像

一样

List<Categories> categories = new ArrayList<Categories>();
while(c.moveToNext()){ 
   categoryName = c.getString(c.getColumnIndex("CategoryName"));
Categories categoryObject=new Categories();
 categoryObject.CategoryName=categoryName;

    categories.add(categoryObject);
   // Toast.makeText(getApplicationContext(), ""+categoryName, 5000).show();

}

categoryName是字符串的类型，您将其添加到类别为

的列表中

for(Category category:response){
    LayoutInflater inflater = getLayoutInflater();
    View row = inflater.inflate(R.layout.my_category, null, false);
    Button button = (Button) row.findViewById(R.id.buttonCategory);
    button.setText(category.CategoryName);
    button.setTag(category.CategoryID);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(Utils.isNetConnected(Categories.this)) {
                Intent intent = new Intent(Categories.this, MainActivity.class);
                intent.putExtra("categoryId", (String) v.getTag());
                intent.putExtra("categoryName", ((Button) v).getText());

                startActivity(intent);
            }else
                Utils.showDialog(Categories.this);
        }
    });
    if(i%2 == 0)
        button.setBackgroundResource(R.drawable.label_with_arrow);
    else
        button.setBackgroundResource(R.drawable.field_with_arrow);
    i++;
    categoriesContainer.addView(row);
}

Answer 2

问题是您使用List初始化了Category，如此List<Category> list = new ArrayList<Category>();。但您尝试添加String而不是Category。您需要做的是将初始化更改为List<String> list = new ArrayList<String>();或添加Category而不是String。

修改在回复您的评论。没有添加类别。在loadCategories()方法中，我看到了此代码

while(c.moveToNext()){ categoryName = c.getString(c.getColumnIndex("CategoryName"));// This is String not a category. You need to change here categories.add(categoryName); // Adding as String }

将此更改为

while(c.moveToNext()){ categoryName = c.getString(c.getColumnIndex("CategoryName")) // Init Category Categories caObj=new Categories(); caObj.yourCategoryName=categoryName; categories.add(caObj); // Now you adding as Cateogry }

如何将项添加到android中的自定义数组列表中

2 个答案: