Question

I have an ArrayList of Path values. I need to convert it into String values and know what all coordinates were covered in the Path.
Here’s the code that I worked up:

private ArrayList<Path> pointsToDraw = new ArrayList<Path>();
private List<String> stringPoints ;



synchronized(pointsToDraw){
                    for(Path path : pointsToDraw)
                    {
                        stringPoints.add(String.valueOf(path));
                    }

                    TextView b1Text = (TextView) findViewById(R.id.GText);
                    for(String s : stringPoints)
                    {
                        b1Text.setText(s);
                    }
                    }

I get an exception during runtime. The following is the log content :

02-21 18:18:29.323: E/AndroidRuntime(512): FATAL EXCEPTION: main
02-21 18:18:29.323: E/AndroidRuntime(512): java.lang.NullPointerException
02-21 18:18:29.323: E/AndroidRuntime(512):  at learn.myandroidapp.hr.HRCanvas$1.onClick(HRCanvas.java:78)
02-21 18:18:29.323: E/AndroidRuntime(512):  at android.view.View.performClick(View.java:3511)
02-21 18:18:29.323: E/AndroidRuntime(512):  at android.view.View$PerformClick.run(View.java:14105)
02-21 18:18:29.323: E/AndroidRuntime(512):  at android.os.Handler.handleCallback(Handler.java:605)
02-21 18:18:29.323: E/AndroidRuntime(512):  at android.os.Handler.dispatchMessage(Handler.java:92)
02-21 18:18:29.323: E/AndroidRuntime(512):  at android.os.Looper.loop(Looper.java:137)
02-21 18:18:29.323: E/AndroidRuntime(512):  at android.app.ActivityThread.main(ActivityThread.java:4424)
02-21 18:18:29.323: E/AndroidRuntime(512):  at java.lang.reflect.Method.invokeNative(Native Method)
02-21 18:18:29.323: E/AndroidRuntime(512):  at java.lang.reflect.Method.invoke(Method.java:511)
02-21 18:18:29.323: E/AndroidRuntime(512):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
02-21 18:18:29.323: E/AndroidRuntime(512):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
02-21 18:18:29.323: E/AndroidRuntime(512):  at dalvik.system.NativeStart.main(Native Method)

Where am I going wrong? Please help!

Answer 1

stringPoints has not been allocated a list.

Change:

private List<String> stringPoints ;

to:

private List<String> stringPoints = new ArrayList<String>();