android - 当我想从另一个 listView 创建 listView 时出错

Question

我有两个类(class)。在第一个类 ListDataActivityInterv 中，我想显示类 ListViewMultipleSelectionActivity 中的所有项目。所以我在第一个类，当我按下按钮添加时我想显示一个 listView(第二堂课)，检查一个，两个项目，当我按下发送按钮时出现在第一个类。我也想存储在表格中选择的这些项目。这是我的第一个类代码:

public class ListDataActivityInterv extends Activity{

    private ListView lsInterventiiView = null;
    private PacientiDB pacientiDB = null;
    private PacientiAdapter adapter = null;
    private ArrayList<Interventii> listInterventii = null;
    private Button buttonCreate2 = null;
    private String text = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.listviewinterventii);

         text = getIntent().getExtras().getString("Pacienti");
         TextView textView1 = (TextView) findViewById(R.id.textView2);
         textView1.setText(text);

         buttonCreate2 = (Button) findViewById(R.id.btnCreateInt);
         buttonCreate2.setOnClickListener(new OnClickListener() {

             @Override
                public void onClick(View v) {
                    Intent intent = new Intent(ListDataActivityInterv.this, ListViewMultipleSelectionActivity.class);
                    startActivity(intent);
                }
        });

            Bundle b = getIntent().getExtras();        
            String[] resultArr = b.getStringArray("selectedItems");       
            ListView lv = (ListView) findViewById(R.id.lsvListInterventii);        
            ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, resultArr);        
            lv.setAdapter(adapter);  
                    }

}

第二类:

public class ListViewMultipleSelectionActivity extends Activity implements
        OnClickListener {   
        Button button;   
        ListView listView;    
        ArrayAdapter<String> adapter; 
        public String text = null;
        private PacientiDB pacientiDB = null;

        /** Called when the activity is first created. */    
        @Override    
        public void onCreate(Bundle savedInstanceState) {       
            super.onCreate(savedInstanceState);        
            setContentView(R.layout.maincheckinterv);  
            text = getIntent().getExtras().getString("Pacienti");
            TextView text1 = (TextView) findViewById(R.id.textViewListInter);
            text1.setText(text);
            findViewsById();         
            String[] sports = getResources().getStringArray(R.array.sports_array);       
            adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_multiple_choice, sports);     
            listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);      
            listView.setAdapter(adapter);        
            button.setOnClickListener(this);    }    

        private void findViewsById() {        
            listView = (ListView) findViewById(R.id.list);       
            button = (Button) findViewById(R.id.testbutton);    }    

        public void onClick(View v) {    
            Interventii interventie = pacientiDB.getInterv(text);
            SparseBooleanArray checked = listView.getCheckedItemPositions();       
            ArrayList<String> selectedItems = new ArrayList<String>();        
            for (int i = 0; i < checked.size(); i++) {           

                int position = checked.keyAt(i);            

                if (checked.valueAt(i))                
                    selectedItems.add(adapter.getItem(position));        }       
            String[] outputStrArr = new String[selectedItems.size()];         
            for (int i = 0; i < selectedItems.size(); i++) {           
                outputStrArr[i] = selectedItems.get(i);  
                interventie = new Interventii();
                interventie.setDenumire(selectedItems.get(i));
                pacientiDB.insertI(interventie);
                }         
            Intent intent = new Intent(getApplicationContext(), ListDataActivityInterv.class);                
            Bundle b = new Bundle();       
            b.putStringArray("selectedItems", outputStrArr);             
            intent.putExtras(b);               
            startActivity(intent);    }
        }

我收到这个错误:

04-30 19:42:55.642: E/AndroidRuntime(4899): FATAL EXCEPTION: main
04-30 19:42:55.642: E/AndroidRuntime(4899): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.medicaldoi/com.example.medicaldoi.ListDataActivityInterv}: java.lang.NullPointerException
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.os.Handler.dispatchMessage(Handler.java:99)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.os.Looper.loop(Looper.java:123)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.app.ActivityThread.main(ActivityThread.java:4627)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at java.lang.reflect.Method.invokeNative(Native Method)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at java.lang.reflect.Method.invoke(Method.java:521)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at dalvik.system.NativeStart.main(Native Method)
04-30 19:42:55.642: E/AndroidRuntime(4899): Caused by: java.lang.NullPointerException
04-30 19:42:55.642: E/AndroidRuntime(4899):     at java.util.Arrays$ArrayList.<init>(Arrays.java:49)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at java.util.Arrays.asList(Arrays.java:171)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:125)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at com.example.medicaldoi.ListDataActivityInterv.onCreate(ListDataActivityInterv.java:45)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-30 19:42:55.642: E/AndroidRuntime(4899):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
04-30 19:42:55.642: E/AndroidRuntime(4899):     ... 11 more

有人可以帮助我吗？有人有其他想法吗？

Answer 1

您的字符串数组为空

        Bundle b = getIntent().getExtras();        
        String[] resultArr = b.getStringArray("selectedItems");  
        if(resultArr==null)
        finish();     
        ListView lv = (ListView) findViewById(R.id.lsvListInterventii);        
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, resultArr);        
        lv.setAdapter(adapter);

现在检查你的应用是否直接关闭，你的字符串数组是否为空。？？

您还可以检查 bundle 是否包含字符串数组......如果它包含数组则它是否为空。

b.containsKey(resultArr)