编程创建的复选框上的NULL对象参考错误

Question

我有一个程序，该程序根据事先活动中的用户输入以编程方式创建复选框。当正确制作复选框时，当需要检查它们是否被检查时，我会收到一个空对象参考错误。我非常清楚，有类似的线程，但是所有线程都包含非常具体的答案，也没有解决我的问题。

 //this part is in the OnCreate portion of the activity   
String [] winQuest;
        winQuest = getResources().getStringArray(R.array.windowQuestions);

        for (int i = 0; i < winQuest.length; i++) {
            TableRow row = new TableRow(this);
            //row.setId(i);
            row.setLayoutParams(basicParams);
            TextView questionText = new TextView(this);
            questionText.setText(winQuest[i]);
            questionText.setTextColor(getColor(R.color.black));
            questionText.setId(R.id.questionText + i);
            row.addView(questionText);
            TableRow row2 = new TableRow(this);
            //row2.setId(i);
            row2.setLayoutParams(basicParams);
            CheckBox checkBox = new CheckBox(this);
            String boxId = i + "1000";
            int id = Integer.parseInt(boxId);
            checkBox.setId(id);
            checkBox.setText(simpleAns[0]);
            row2.addView(checkBox);
            //subChecks.add(checkBox);
            TableRow row3 = new TableRow(this);
            //row3.setId(i);
            row3.setLayoutParams(basicParams);
            CheckBox checkBox2 = new CheckBox(this);
            String boxId2 = i + "2000";
            int id2 = Integer.parseInt(boxId2);
            checkBox.setId(id2);
            checkBox2.setText(simpleAns[1]);
            row3.addView(checkBox2);
            //subChecks.add(checkBox2);
            TableRow row4 = new TableRow(this);
            //row4.setId(i);
            row4.setLayoutParams(basicParams);
            CheckBox checkBox3 = new CheckBox(this);
            String boxId3 = i + "3000";
            int id3 = Integer.parseInt(boxId3);
            checkBox.setId(id3);
            checkBox3.setText(simpleAns[2]);
            row4.addView(checkBox3);
            //subChecks.add(checkBox3);
            TableRow row5 = new TableRow(this);
            //row5.setId(i);
            row5.setLayoutParams(basicParams);
            EditText addtlNotesText = new EditText(this);
            addtlNotesText.setHint(getResources().getString(R.string.notes));
            String textId4 = i + "4000";
            int id4 = Integer.parseInt(textId4);
            checkBox.setId(id4);
            row5.addView(addtlNotesText);
            noteText.add(addtlNotesText);
            rootLayout.addView(row);
            rootLayout.addView(row2);
            rootLayout.addView(row3);
            rootLayout.addView(row4);
            rootLayout.addView(row5);
        }

    //this part happens OnClick
    String [] winQuest;
                winQuest = getResources().getStringArray(R.array.windowQuestions);
                for(int i = 0; i < winQuest.length; i++){
                    fieldNoteResponses = "";
                    String subCheck = i + "1000";
                    String subCheck2 = i + "2000";
                    String subCheck3 = i + "3000";
                    int box = Integer.parseInt(subCheck);
                    final CheckBox subChecked1 = findViewById(box);
                    int box2 = Integer.parseInt(subCheck2);
                    final CheckBox subChecked2 = findViewById(box2);
                    int box3 = Integer.parseInt(subCheck3);
                    final CheckBox subChecked3 = findViewById(box3);
                        if (subChecked1.isChecked()) {
                            fieldNoteResponses = "Yes";
                        }
                        if (subChecked2.isChecked()){
                            fieldNoteResponses = "No";
                        }
                        if (subChecked3.isChecked()) {
                            fieldNoteResponses = "Not Applicable";
                        }
                    String addNotes = "";
                    String textCheck = i + "4000";
                    int textId = Integer.parseInt(textCheck);
                    final EditText addText = findViewById(textId);
                    addNotes = addText.getText().toString();
    }

运行此代码时，我在" if（subchecked1.ischecked（））"一部分上获得了null对象引用。

在这里参考是错误：

    E/AndroidRuntime: FATAL EXCEPTION: main
              Process: redcaribou.abbphotoorganizerv2, PID: 4942
              java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.widget.CheckBox.isChecked()' on a null object reference
                  at redcaribou.abbphotoorganizerv2.FirstCheckList.onClick(FirstCheckList.java:394)
                  at android.view.View.performClick(View.java:5623)
                  at android.view.View$PerformClick.run(View.java:22433)
                  at android.os.Handler.handleCallback(Handler.java:751)
                  at android.os.Handler.dispatchMessage(Handler.java:95)
                  at android.os.Looper.loop(Looper.java:154)
                  at android.app.ActivityThread.main(ActivityThread.java:6314)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:872)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762)

Answer 1

问题在您的findViewById(box)和其他FindViewById（）方法调用中。您需要在此处提供XML元素ID；像findViewById(R.id.checkBox1)。它实际上解决了int值。我建议您在findviewbyid（）中进行一些阅读。