Question

单击单选按钮时，我的应用程序崩溃了。无线电按钮是动态生成的。但是，当我提到那个按钮时，它会崩溃。

崩溃发生在这里显示小吃店。我相信什么时候当我为所选Button调用方法getText时。

我该如何解决？

这是我的代码：

public class ListActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    String[] filename = getApplicationContext().fileList();

    addRadioButtons(filename.length, filename);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            RadioGroup rd = (RadioGroup) findViewById(R.id.file_radio_group);
            int id_Btn = rd.getCheckedRadioButtonId() ;
            RadioButton selectedRB = (RadioButton) findViewById(id_Btn) ;

            Snackbar.make(view, "Replace with your own action "+selectedRB.getText().toString(), Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });



}
public void addRadioButtons(int number,String[] filenames) {

    for (int row = 0; row < 1; row++) {
        RadioGroup ll = new RadioGroup(this);
        ll.setOrientation(LinearLayout.VERTICAL);

        for (int i = 1; i <= number; i++) {
            RadioButton rdbtn = new RadioButton(this);
            rdbtn.setId((row * 2) + i);
            rdbtn.setText(filenames[i-1]);
            //rdbtn.setText("Radio " + rdbtn.getId());
            rdbtn.setTextSize(25);
            ll.addView(rdbtn);
        }
        ((ViewGroup) findViewById(R.id.file_radio_group)).addView(ll);
    }
}
}

这是我的Logcat

 11-01 19:04:26.460 6743-6743/alahdal.amjad.newloginproject E/AndroidRuntime: FATAL EXCEPTION: main
 Process: alahdal.amjad.newloginproject, PID: 6743
 java.lang.NullPointerExceptionat 
 alahdal.amjad.newloginproject.ListActivity$1.onClick(ListActivity.java:39)
 at android.view.View.performClick(View.java:4438)
 at android.view.View$PerformClick.run(View.java:18422)
 at android.os.Handler.handleCallback(Handler.java:733)
 at android.os.Handler.dispatchMessage(Handler.java:95)
 at android.os.Looper.loop(Looper.java:136)
 at android.app.ActivityThread.main(ActivityThread.java:5017)
 at java.lang.reflect.Method.invokeNative(Native Method)
 at java.lang.reflect.Method.invoke(Method.java:515)     atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
 at dalvik.system.NativeStart.main(Native Method)

无论如何，我不会＆＃39;知道它崩溃的原因。请帮忙

Answer 1

在这里，我不清楚你的要求，但是没有想到在xml中添加另一个无线电组。这是更正版本工作正常。

 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    final RadioGroup radioGroup = (RadioGroup) findViewById(R.id.file_radio_group);
    String[] filename = getApplicationContext().fileList();
    addRadioButtons(radioGroup, filename.length, filename);
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            int id_Btn = radioGroup.getCheckedRadioButtonId();
            for (int count = 0; count < radioGroup.getChildCount(); count++) {
                if (radioGroup.getChildAt(count).getId() == id_Btn) {
                    RadioButton radioButton = (RadioButton) radioGroup.getChildAt(count);
                    Snackbar.make(view, "Replace with your own action " + radioButton.getText().toString(), Snackbar.LENGTH_LONG)
                            .setAction("Action", null).show();
                }
            }
        }
    });
}

public void addRadioButtons(RadioGroup radioGroup, int number, String[] filenames) {
    radioGroup.setOrientation(LinearLayout.VERTICAL);
    for (int i = 1; i <= number; i++) {
        RadioButton rdbtn = new RadioButton(this);
        rdbtn.setId((i * 2) + i);
        rdbtn.setText(filenames[i - 1]);
        rdbtn.setTextSize(25);
        radioGroup.addView(rdbtn);
    }
}

Answer 2

如果未选择单选按钮 rd.getCheckedRadioButtonId() 将返回-1，这将不是任何视图的ID，因此findViewById无法找到视图。

在使用id_Btn查找视图之前检查-1。

public void onClick(View view) {
    RadioGroup rd = (RadioGroup) findViewById(R.id.file_radio_group);
    int id_Btn = rd.getCheckedRadioButtonId() ;
    if (id_Btn != -1) {
        RadioButton selectedRB = (RadioButton) findViewById(id_Btn) ;
    } else {
        //Handle case if no button is selected
    }

    Snackbar.make(view, "Replace with your own action "+selectedRB.getText().toString(), Snackbar.LENGTH_LONG)
                .setAction("Action", null).show();
    }

Answer 3

public class ListActivity extends AppCompatActivity {
private RadioGroup ll; 
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
String[] filename = getApplicationContext().fileList();

addRadioButtons(filename.length, filename);

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        RadioGroup rd = (RadioGroup) findViewById(R.id.file_radio_group);
        int id_Btn = rd.getCheckedRadioButtonId() ;
        RadioButton selectedRB = (RadioButton) findViewById(id_Btn) ;

        Snackbar.make(view, "Replace with your own action "+selectedRB.getText().toString(), Snackbar.LENGTH_LONG)
                .setAction("Action", null).show();
    }
});



}


  public void addRadioButtons(int number,String[] filenames) {

for (int row = 0; row < 1; row++) {
    ll = new RadioGroup(this);
    ll.setOrientation(LinearLayout.VERTICAL);

    for (int i = 1; i <= number; i++) {
        RadioButton rdbtn = new RadioButton(this);
        rdbtn.setId((row * 2) + i);
        rdbtn.setText(filenames[i-1]);
        //rdbtn.setText("Radio " + rdbtn.getId());
        rdbtn.setTextSize(25);
        ll.addView(rdbtn);
    }
    ((ViewGroup) findViewById(R.id.file_radio_group)).addView(ll);
}
}
}

我的应用程序崩溃列表单选按钮

3 个答案: