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分享程序员开发的那些事...
且构网 - 分享程序员编程开发的那些事

使用数组列表的Andr​​oid微调数据绑定

更新时间:2023-11-16 12:44:46

ArrayAdapter 尽量显示你的位置 -objects为字符串(这将导致十六进制值),通过调用Object.toString()$c$c>-method.它的默认实现返回:

The ArrayAdapter tries to display your Location-objects as strings (which causes the Hex-values), by calling the Object.toString()-method. It's default implementation returns:

[...]组成的类的名称的字符串,它的对象   是一个实例,该符号字符'@',和无符号   十六进制重的对象的哈希code presentation。

[...] a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object.

为了让 ArrayAdadpter 显示一些项目列表中真正有用的,你可以覆盖的toString() - 方法返回一些有意义的:

To make the ArrayAdadpter show something actually useful in the item list, you can override the toString()-method to return something meaningful:

@Override
public String toString(){
  return "Something meaningful here...";
}


另一种方式做,这是,延长 BaseAdapter 实施 SpinnerAdapter 创建自己的适配器,它知道,在的ArrayList 元素是对象,以及如何使用这些对象的属性。


Another way to do this is, to extend BaseAdapter and implement SpinnerAdapter to create your own Adapter, which knows that the elements in your ArrayList are objects and how to use the properties of those objects.

我是打了一下周围,我设法获得一些工作:

I was playing around a bit and I managed to get something to work:

public class Main extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // Create and display a Spinner:
        Spinner s = new Spinner(this);
        AbsListView.LayoutParams params = new AbsListView.LayoutParams(
                ViewGroup.LayoutParams.FILL_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT
        );
        this.setContentView(s, params);
        // fill the ArrayList:
        List<Guy> guys = new ArrayList<Guy>();
        guys.add(new Guy("Lukas", 18));
        guys.add(new Guy("Steve", 20));
        guys.add(new Guy("Forest", 50));
        MyAdapter adapter = new MyAdapter(guys);
        // apply the Adapter:
        s.setAdapter(adapter);
        // onClickListener:
        s.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            /**
             * Called when a new item was selected (in the Spinner)
             */
            public void onItemSelected(AdapterView<?> parent,
                                       View view, int pos, long id) {
                Guy g = (Guy) parent.getItemAtPosition(pos);
                Toast.makeText(
                        getApplicationContext(),
                        g.getName()+" is "+g.getAge()+" years old.",
                        Toast.LENGTH_LONG
                ).show();
            }

            public void onNothingSelected(AdapterView parent) {
                // Do nothing.
            }
        });
    }

    /**
     * This is your own Adapter implementation which displays
     * the ArrayList of "Guy"-Objects.
     */
    private class MyAdapter extends BaseAdapter implements SpinnerAdapter {

        /**
         * The internal data (the ArrayList with the Objects).
         */
        private final List<Guy> data;

        public MyAdapter(List<Guy> data){
            this.data = data;
        }

        /**
         * Returns the Size of the ArrayList
         */
        @Override
        public int getCount() {
            return data.size();
        }

        /**
         * Returns one Element of the ArrayList
         * at the specified position.
         */
        @Override
        public Object getItem(int position) {
            return data.get(position);
        }

        @Override
        public long getItemId(int i) {
            return i;
        }
        /**
         * Returns the View that is shown when a element was
         * selected.
         */
        @Override
        public View getView(int position, View recycle, ViewGroup parent) {
            TextView text;
            if (recycle != null){
                // Re-use the recycled view here!
                text = (TextView) recycle;
            } else {
                // No recycled view, inflate the "original" from the platform:
                text = (TextView) getLayoutInflater().inflate(
                        android.R.layout.simple_dropdown_item_1line, parent, false
                );
            }
            text.setTextColor(Color.BLACK);
            text.setText(data.get(position).name);
            return text;
        }


    }

    /**
     * A simple class which holds some information-fields
     * about some Guys.
     */
    private class Guy{
        private final String name;
        private final int age;

        public Guy(String name, int age){
            this.name = name;
            this.age = age;
        }

        public String getName() {
            return name;
        }

        public int getAge() {
            return age;
        }
    }
}

我完全注释的code,如果你有任何问题,请不要犹豫,问他们。

I fully commented the code, if you have any questions, don't hesitate to ask them.