Question

我正在使用Android和Spinners，我需要一些帮助。我有一个创建两个微调器和一个按钮的类。第一个微调器是我的类别，第二个是我的子类别。我想要做的是动态更新第二个微调器（spinner2）。我一直在尝试使用adapter2.clear（），但崩溃了android，错误“无法启动活动componentinfo不支持的操作”

这是我的代码：

public class MyClass extends MyBaseClass
{
    int category;
    int sub_category;
    ArrayAdapter<String> adapter2;


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.quizes);

        //CATEGORY INFO
        final String[] items1 = new String[] {"One", "Two", "Three"};
        final Spinner spinner1 = (Spinner) findViewById(R.id.spinner1);
        ArrayAdapter<String> adapter1 = new ArrayAdapter<String>(this,
                    android.R.layout.simple_spinner_item, items1);
        adapter1.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner1.setAdapter(adapter1);

        //SUBCATEGORY INFO
        final String[] items2 = new String[] {"SOne", "STwo", "SThree"};
        final Spinner spinner2 = (Spinner) findViewById(R.id.spinner2);
        adapter2 = new ArrayAdapter<String>(this,
                    android.R.layout.simple_spinner_item, items2);
        adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner2.setAdapter(adapter2);


        // Capture our button from layout
        Button button = (Button)findViewById(R.id.button1);
        // Register the onClick listener with the implementation above
        button.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                // do something when the button is clicked



                startActivity(new Intent(MyClass.this, GoToOtherClass.class));
              } 
        });


        //SELECTOR CONTROL FOR SPINNER1 {CATEGORY}
        spinner1.setOnItemSelectedListener(new OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
                MyClass.this.category = spinner1.getSelectedItemPosition();

        //OTHER STUFF


            }
            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
            }
        });

        //SELECTOR CONTROL FOR SPINNER2 {SUB-CATEGORY}
        spinner2.setOnItemSelectedListener(new OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {

                MyClass.this.sub_category = spinner2.getSelectedItemPosition();

        //OTHER STUFF

            }
            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);
        return true;
    }
}

我理解.clear（）/。add（）方法，但是每当我尝试clear（）/ add（）我的程序崩溃时，我需要做些什么才能解决问题所以我可以更改spinner2的内容我的子类别清单？任何建议都会有所帮助，因为我花了几个小时做以下事情：

对象t = adapter2.getitem（0）; spinner2.remove（（String）t）;

或者adapter2.clear（）以及其他一些技巧，我没有进一步的想法。我还在学习android。我曾尝试在stackoverflow和google上查看其他帖子，但不确定如何让他们的想法有效。

Answer 1

更改第二个微调器的内容后，需要调用adapter2.notifyDataSetChanged()。如果没有该调用，UI将不会使用Spinner的新内容进行更新，并且您也可能在引用不存在的内容时遇到问题。

Answer 2

试试此代码..

public class MainActivity extends Activity {

Spinner sp1,sp2;
ArrayAdapter<String> adp1,adp2;
List<String> l1,l2;
int pos;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    l1=new ArrayList<String>();

    l1.add("A");
    l1.add("B");

    sp1= (Spinner) findViewById(R.id.spinner1);
    sp2= (Spinner) findViewById(R.id.spinner2);

    adp1=new ArrayAdapter<String> (this,android.R.layout.simple_dropdown_item_1line,l1);
    adp1.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line);
    sp1.setAdapter(adp1);

    sp1.setOnItemSelectedListener(new OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> arg0, View arg1,
                int arg2, long arg3) {
            // TODO Auto-generated method stub
            pos=arg2;
            add();

        }

        private void add() {
            // TODO Auto-generated method stub
            Toast.makeText(getBaseContext(), ""+pos, Toast.LENGTH_SHORT).show();

            switch(pos)
            {
            case 0:
                l2= new ArrayList<String>();                    
                l2.add("A 1");
                l2.add("A 2");

                adp2=new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_dropdown_item_1line,l2);
                adp2.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line);
                sp2.setAdapter(adp2);

                select();

                break;
            case 1:
                l2= new ArrayList<String>();                    
                l2.add("B 1");
                l2.add("B 2");

                adp2=new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_dropdown_item_1line,l2);
                adp2.setDropDownViewResource(android.R.layout.simple_dropdown_item_1line);
                sp2.setAdapter(adp2);

                select();

                break;
            }

        }

        private void select() {
            // TODO Auto-generated method stub

            sp2.setOnItemSelectedListener(new OnItemSelectedListener() {

                @Override
                public void onItemSelected(AdapterView<?> arg0, View arg1,
                        int arg2, long arg3) {
                    // TODO Auto-generated method stub
                    Toast.makeText(getBaseContext(), "Test "+arg2, Toast.LENGTH_SHORT).show();

                }

                @Override
                public void onNothingSelected(AdapterView<?> arg0) {
                    // TODO Auto-generated method stub

                }
            });

        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0) {
            // TODO Auto-generated method stub

        }
    });
    }

}

Android动态微调器更新

2 个答案: