Android studio错误:java.lang.NullPointerException [重复]

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这个问题在这里已有答案:

我正在尝试从用户那里获取输入并创建给定数字的列表。我收到java.lang.NULLpointerException但我在代码中找不到任何错误。将用户输入从MainActivity传递到选择器Activity。主要活动完美无缺。

主要信息

公共类MainActivity扩展AppCompatActivity {

DatePicker dp;
EditText et;
Button b;
String d;
int e;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);
    dp = (DatePicker)findViewById(R.id.datePicker3);
    et = (EditText)findViewById(R.id.editText);
    b = (Button)findViewById(R.id.button);
    d = dp.toString();

    //final int k = Integer.parseInt(e);
    //Integer.
    b.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent i = new Intent(MainActivity.this, selector.class);
            Bundle extras = new Bundle();
            e = Integer.parseInt(et.getText().toString());
            i.putExtra("date",d);
            i.putExtra("number", e);
            i.putExtras(extras);


            startActivity(i);










        }
    });





}

}

Selector Acitivity公共类选择器扩展AppCompatActivity {

Button b;
TextView abs;

String []as;
boolean[] pora;
ArrayList<Integer> mabs = new ArrayList<>();


@Override
protected void onCreate(Bundle savedInstanceState) {


    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_selector);
    b=(Button)findViewById(R.id.btnOrder);
    abs=(TextView)findViewById(R.id.tvItemSelected);
    Bundle extras = getIntent().getExtras();


    int result = extras.getInt("number",5);
    String v2 =Integer.toString(result);
    abs.setText(v2);

    as = new String[result+1];
    for(int i=1;i<=result;i++)
    {

        as[i]=Integer.toString(i);
    }
    abs.append(as[2]);

    pora=new boolean[as.length];
    b.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View view) {

            AlertDialog.Builder mBuilder = new AlertDialog.Builder(selector.this);

            mBuilder.setTitle("kjsr7c attendace");


            mBuilder.setMultiChoiceItems(as, pora, new DialogInterface.OnMultiChoiceClickListener(){
                @Override

                public void onClick(DialogInterface dialogInterface, int position, boolean isChecked) {
                    if(isChecked){

                        mabs.add(position);

                    }else{

                        mabs.remove((Integer.valueOf(position)));

                    }

                }

            });



            mBuilder.setCancelable(false);

            mBuilder.setPositiveButton("OK", new DialogInterface.OnClickListener() {

                @Override

                public void onClick(DialogInterface dialogInterface, int which) {

                    String item = "";

                    for (int i = 1; i < mabs.size(); i++) {

                        item = item + as[mabs.get(i)];

                        if (i != mabs.size() - 1) {

                            item = item + ", ";

                        }

                    }

               abs.setText(item);

                }

            });



            mBuilder.setNegativeButton("DISMISS", new DialogInterface.OnClickListener() {

                @Override

                public void onClick(DialogInterface dialogInterface, int i) {

                    dialogInterface.dismiss();

                }

            });



            mBuilder.setNeutralButton("CLEAR", new DialogInterface.OnClickListener() {

                @Override

                public void onClick(DialogInterface dialogInterface, int which) {

                    for (int i = 1; i < pora.length; i++) {

                        pora[i] = false;

                        mabs.clear();

                      abs.setText("");

                    }

                }

            });



            AlertDialog mDialog = mBuilder.create();

            mDialog.show();

        }

    });

}

}

logcat的

FATAL EXCEPTION: main
                                                                         Process: com.example.sankar.kjsr7c, PID: 3945
                                                                         java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
                                                                             at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:409)
                                                                             at android.widget.ArrayAdapter.getView(ArrayAdapter.java:371)
                                                                             at android.support.v7.app.AlertController$AlertParams$1.getView(AlertController.java:974)
                                                                             at android.widget.AbsListView.obtainView(AbsListView.java:2363)
                                                                             at android.widget.ListView.measureHeightOfChildren(ListView.java:1326)
                                                                             at android.widget.ListView.onMeasure(ListView.java:1233)
                                                                             at android.view.View.measure(View.java:19857)
                                                                             at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
                                                                             at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                                             at android.view.View.measure(View.java:19857)
                                                                             at android.support.v7.widget.AlertDialogLayout.tryOnMeasure(AlertDialogLayout.java:133)
                                                                             at android.support.v7.widget.AlertDialogLayout.onMeasure(AlertDialogLayout.java:63)
                                                                             at android.view.View.measure(View.java:19857)
                                                                             at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
                                                                             at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                                             at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
                                                                             at android.view.View.measure(View.java:19857)
                                                                             at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
                                                                             at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                                             at android.view.View.measure(View.java:19857)
                                                                             at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
                                                                             at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                                             at android.view.View.measure(View.java:19857)
                                                                             at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
                                                                             at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
                                                                             at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
                                                                             at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
                                                                             at android.view.View.measure(View.java:19857)
                                                                             at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6083)
                                                                             at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
                                                                             at com.android.internal.policy.DecorView.onMeasure(DecorView.java:689)
                                                                             at android.view.View.measure(View.java:19857)
                                                                             at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2275)
                                                                             at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1339)
                                                                             at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1619)
                                                                             at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1254)
                                                                             at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6337)
                                                                             at android.view.Choreographer$CallbackRecord.run(Choreographer.java:874)
                                                                             at android.view.Choreographer.doCallbacks(Choreographer.java:686)
                                                                             at android.view.Choreographer.doFrame(Choreographer.java:621)
                                                                             at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:860)
                                                                             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:6119)
                                                                             at java.lang.reflect.Method.invoke(Native Method)
                                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
                                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
答案

在使用Integer.parseInt之前检查EditText是否为空。最有可能的是,Empty EditText将为getText()操作返回null。

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