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这是TeacherLoginPage.java，oncreate 通过从数据库中获取数据来设置布局。在onCreate 方法中，我使用setid() 方法分配了复选框的ID。这里的问题是当我单击更新按钮时，应用程序强制关闭。我认为这条线cbArray.add((CheckBox) findViewById(resId));是行不通的。我应该写成（R.id.resId）吗？

TeacherLoginPage.java

    LinearLayout my_layout = (LinearLayout) findViewById(R.id.layout_checklist);

    for (int i = 0; i < Array_Count; i++) {
        TableRow row = new TableRow(this);
        row.setId(i);
        row.setLayoutParams(new LayoutParams(
                android.widget.TableRow.LayoutParams.FILL_PARENT,
                android.widget.TableRow.LayoutParams.WRAP_CONTENT));

        CheckBox checkBox = new CheckBox(this);

        checkBox.setId(i);
        checkBox.setText(Roll_array.get(i));
        row.addView(checkBox);
        my_layout.addView(row);
    }  

 public void onClick(View v) {
        // TODO Auto-generated method stub

        ArrayList<CheckBox> cbArray = new ArrayList<CheckBox>();
        int[] cvalue = null;
        for (int j = 0; j < Array_Count; j++) {
            int resId = getResources().getIdentifier(String.valueOf(j), "id", getPackageName());
            cbArray.add((CheckBox) findViewById(resId));
            cvalue[j] = toNumericalValue(cbArray.get(j).isChecked());
        }
        insertAttendanceDatabase(TeacherLoggedInPage.this, cvalue);

    }

    private void insertAttendanceDatabase(
            TeacherLoggedInPage teacherLoggedInPage, int[] cvalue) {
        // TODO Auto-generated method stub

        SQLiteDatabase db = myDb.getWritableDatabase();

        int length = cvalue.length;

        ContentValues cv = new ContentValues();
        cv.put("teacher_id", t_id);
        cv.put("time", DateFormat.getDateTimeInstance().format(new Date()));
        for (int i = 0; i < cvalue.length; i++) {

            cv.put(Roll_array.get(i), cvalue[i]);
        }

        try {
            db.insert(DbHelper.ATTENDANCE_TABLE, null, cv);

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    private int toNumericalValue(boolean checked) {
        // TODO Auto-generated method stub
        if (checked)
            return 1;
        else
            return 0;
    }

这是LogCat

08-12 04:17:14.970: D/AndroidRuntime(385): Shutting down VM
08-12 04:17:14.999: W/dalvikvm(385): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
08-12 04:17:15.009: E/AndroidRuntime(385): FATAL EXCEPTION: main
08-12 04:17:15.009: E/AndroidRuntime(385): java.lang.ClassCastException: android.widget.TableRow
08-12 04:17:15.009: E/AndroidRuntime(385):  at com.example.attendancesystem.TeacherLoggedInPage.onClick(TeacherLoggedInPage.java:123)
08-12 04:17:15.009: E/AndroidRuntime(385):  at android.view.View.performClick(View.java:2408)
08-12 04:17:15.009: E/AndroidRuntime(385):  at android.view.View$PerformClick.run(View.java:8816)
08-12 04:17:15.009: E/AndroidRuntime(385):  at android.os.Handler.handleCallback(Handler.java:587)
08-12 04:17:15.009: E/AndroidRuntime(385):  at android.os.Handler.dispatchMessage(Handler.java:92)
08-12 04:17:15.009: E/AndroidRuntime(385):  at android.os.Looper.loop(Looper.java:123)
08-12 04:17:15.009: E/AndroidRuntime(385):  at android.app.ActivityThread.main(ActivityThread.java:4627)
08-12 04:17:15.009: E/AndroidRuntime(385):  at java.lang.reflect.Method.invokeNative(Native Method)
08-12 04:17:15.009: E/AndroidRuntime(385):  at java.lang.reflect.Method.invoke(Method.java:521)
08-12 04:17:15.009: E/AndroidRuntime(385):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-12 04:17:15.009: E/AndroidRuntime(385):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-12 04:17:15.009: E/AndroidRuntime(385):  at dalvik.system.NativeStart.main(Native Method)
08-12 04:17:38.108: I/Process(385): Sending signal. PID: 385 SIG: 9
4

4 回答 4

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您正在尝试将 aTableRow转换为 a CheckBox。确保 id 指向一个CheckBox

于 2013-08-12T09:00:05.997 回答
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您的问题是您设置了两次 ID：

row.setId(i);

然后

checkBox.setId(i);

如果你这样做findViewById(resId)，那么它会返回它找到的第一个带有这个 ID 的元素，它是 a TableRow，而不是CheckBox你期望的 a 。因此ClassCastException.

于 2013-08-12T09:26:48.247 回答
0

重点是，您TableRow之前分配了 id，但是当您从 resId 检索时，您将其转换CheckBox为导致问题的原因。检查这个：

for (int i = 0; i < Array_Count; i++) {
        TableRow row = new TableRow(this);
        row.setId(i);
        row.setLayoutParams(new LayoutParams(
                android.widget.TableRow.LayoutParams.FILL_PARENT,
                android.widget.TableRow.LayoutParams.WRAP_CONTENT));

和这个：

ArrayList<CheckBox> cbArray = new ArrayList<CheckBox>();
        int[] cvalue = null;
        for (int j = 0; j < Array_Count; j++) {
            int resId = getResources().getIdentifier(String.valueOf(j), "id", getPackageName());
            cbArray.add((CheckBox) findViewById(resId));
            cvalue[j] = toNumericalValue(cbArray.get(j).isChecked());
        }

希望能帮助到你。

于 2013-08-12T09:04:07.010 回答
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您正在为 TableRow 和 Checkbox 分配相同的 id。作为

 row.setId(i);

 checkBox.setId(i);

只是评论//row.setId(i);

于 2013-08-12T09:04:07.287 回答