从先前的微调器选择的项目动态更改微调器中的字符串名称

Question

我想动态更改微调器中的字符串名称 android 来自之前微调器选择的项目。

这是我的 Activity class:

public class SelectionActivity extends AppCompatActivity implements View.OnClickListener {

    final String LOG = "Selection";
    private Spinner spBranch;
    private Spinner spSection;
    private Spinner spSemester,spSubject;
    private Button btnSend;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.selection);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);


        spBranch = (Spinner) findViewById(R.id.spBranch1);
        spSection = (Spinner) findViewById(R.id.spSection1);
        spSemester = (Spinner) findViewById(R.id.spSemester1);
        spSubject=(Spinner) findViewById(R.id.spSubject1);
        String[] items1 = new String[]{"CSE", "EEE", "EE", "ECE", "MECH", "CIVIL"};
        ArrayAdapter<String> adapter1 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, items1);
        spBranch.setAdapter(adapter1);
        String[] items2 = new String[]{"A", "B", "C", "D", "E", "F"};
        ArrayAdapter<String> adapter2 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, items2);
        spSection.setAdapter(adapter2);
        String[] items3 = new String[]{"1st", "2nd", "3rd", "4th", "5th", "6th", "7th", "8th"};
        ArrayAdapter<String> adapter3 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, items3);
        spSemester.setAdapter(adapter3);

        String[] items4 = new String[]{"Math 1", "Programming in C", "Thermodynamics", "Communication English", "Physics", "Basic Electronics"};
        String[] items5 = new String[]{"Chemistry", "Data Structure", "Mechanics", "Buiseness English", "Basic Electrical Engineering l ", "Math 2"};
        if(spSemester.getSelectedItem().toString().equals("1st"))
        {

            ArrayAdapter<String> adapter4 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item,items4);
            spSubject.setAdapter(adapter4);

        }
        else{

            ArrayAdapter<String> adapter4 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item,items5);
            spSubject.setAdapter(adapter4);

        }
        btnSend = (Button) findViewById(R.id.btnSend);

    } 



    @Override
    public void onClick(View v) {
        Intent in = new Intent(SelectionActivity.this, ListActivity.class);
        startActivity(in);
        HashMap postData = new HashMap();
        postData.put("txtBranch", spBranch.getSelectedItem().toString());
        postData.put("txtSection", spSection.getSelectedItem().toString());
        postData.put("txtSemester", spSemester.getSelectedItem().toString());

    }
}

我在这行 r 处遇到错误 spSubject.setAdapter(adapter4); 刚接触andorid，有没有其他方法可以做到这一点

Answer 1

尝试使用此代码了解是否选择了 spSemester 微调器中的第一个索引

if(spSemester.getSelectedItemPosition() == 1)
{

    ArrayAdapter<String> adapter4 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item,items4);
    spSubject.setAdapter(adapter4);

 }
 else{

    ArrayAdapter<String> adapter4 = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item,items5);
                spSubject.setAdapter(adapter4);

}

Answer 2

请注意，您发布的所有代码将在 Activity 创建时立即运行。这就是 onCreate() 方法的重点。当用户在任何 Spinner 中选择一个新项目时，什么都不会发生。如果您希望 Spinner 更动态地更改，您需要添加适当的事件侦听器。特别是，您需要实施 AdapterView.OnItemSelectedListener. An example is shown here。我建议创建单独的 classes 来实现监听器接口，而不是在你的 activity class.

上实现它

从先前的微调器选择的项目动态更改微调器中的字符串名称

Change the string names in spinner dynamically from previous spinner chosen item

android

spinner

android-spinner