我的应用崩溃与列表单选按钮

Question

当我单击单选按钮时，我的应用程序崩溃了。单选按钮是动态生成的。但是，当我提到该按钮时，它会崩溃。

崩溃发生在这里，当显示小吃栏时。我相信当 当我为所选按钮调用方法获取文本时。

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);
    }
}
}

这是我的日志猫

 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，我不知道它为什么崩溃。请帮忙

Answer 1

你

去吧，我不清楚你的要求，但不要想到在 xml 中已经有一个单选组中添加另一个单选组。这是更正的版本工作正常。

 @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，这不是任何视图的 ID，因此findViewById找不到视图。

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);
}
}
}