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Thread: CheckBox/Spinner error Error

  1. #1
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    Default CheckBox/Spinner error Error

    For some reason, when i check for the input of the spinner using an array with a switch statement it does this weird thing. If i use any sort of "if-statement" "for-loop" any thing of that nature, it wont through an error, just when I open the virtual device it will say app has stopped working. When I remove the if-statement or for-loop it will work fine. The reason I need to use an if statement is because i want to check if the checkbox is checked.

    Heres my code:
    package com.example.gcfcalculator;
     
    import android.app.Activity;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.AdapterView;
    import android.widget.AdapterView.OnItemSelectedListener;
    import android.widget.ArrayAdapter;
    import android.widget.Button;
    import android.widget.CheckBox;
    import android.widget.EditText;
    import android.widget.Spinner;
    import android.widget.TextView;
     
    public class MainActivity extends Activity implements OnItemSelectedListener {
     
    	Spinner spinner;
    	String[] paths = {"Rectangle", "Circle", "Triangle"};
    	Button equals;
    	TextView parm1, parm2;
    	EditText value1, value2;
    	CheckBox checkArea, checkPerm;
    	Boolean checkedArea = false, checkedPerm = false;
     
     
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
     
            ArrayAdapter<String> adapter = new ArrayAdapter<String>(MainActivity.this,
    android.R.layout.simple_spinner_item, paths);
            spinner = (Spinner) findViewById(R.id.spinner);
            spinner.setAdapter(adapter);
            spinner.setOnItemSelectedListener(this);
     
        }
     
    	@Override
    	public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
    		int position = spinner.getSelectedItemPosition();
    		switch(position){
    		case 0:
    			//Rectangle
                            //Problem happens here!!!
    			if(checkArea.isChecked()){
                               System.out.println("Area is checked");
                            }
    			break;
    		case 1:
    			//Square
    			break;
    		case 2:
    			//Triangle
    			break;
    		}
     
    	}
     
    	@Override
    	public void onNothingSelected(AdapterView<?> arg0) {
    		// TODO Auto-generated method stub
     
    	}
     
    }


  2. #2
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    Default Re: CheckBox/Spinner error Error

    The issue is that checkedArea is never instantiated. You will either need to programatically create it or define is by findByView like you did with the spinner.

    checkedArea = (CheckBox)  findViewById(R.id.checkedArea);   //Whatever the id is in the xml layout


    Also, I'd advise using an anonymous class for the listener instead of implementing it at the activity level.

    spinner.setOnItemSelectedListener( new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) 
        {
              switch (position) {
                   //etc
              }
        }
     
     
        @Override
        public void onNothingSelected(AdapterView<?> parentView) {  }
    });

    Also, I'd advise using a string array in the strings.xml instead of defining it in code. IIRC eclipse will complain about defining strings like that.

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