java - (Hash-)Map has entry, get delivers null -

i have no idea happening here. have hashmap following keyset of size 4:

steps.keyset() (java.util.hashmap$keyset) [init_fzlist, init_data, install_database, prompt_geraeteid] 

init_fzlist, init_data, install_database , prompt_geraeteid values of enum.

also entryset delivers 4 entries.

steps.entryset() (java.util.hashmap$entryset) [init_fzlist=de.ansat.terminal.activity.widgets.pendingcheckbox{b50cb4e0 v.e..... ......i. 24,524-456,666},  init_data=de.ansat.terminal.activity.widgets.pendingcheckbox{b50c8748 v.e..... ......i. 24,350-456,524},  install_database=de.ansat.terminal.activity.widgets.pendingcheckbox{b508e288 v.e..... ......i. 24,68-456,209},  prompt_geraeteid=de.ansat.terminal.activity.widgets.pendingcheckbox{b50c59b0 v.e..... ......i. 24,209-456,350}] 

but if this:

steps.get(install_database)  null 

the map returns null , of cause nullpointerexception if try work resulting object.

this running in android activity. i'm using android 4.2.2 on api level 17

[edit]

private map<installsteps, pendingcheckbox> steps = new hashmap<installsteps, pendingcheckbox>(); 

is field of activity class.

i have several asynctasks working on map, represents progress of installation process.

pendingcheckbox view extending linearlayout.

[edit2] steps filled in oncreate(..) way:

    pendingcheckbox installdb = new pendingcheckbox(installactivity.this);     installdb.settext(install_database);     installdb.setchecked(false);     installdb.setlayoutparams(layoutparams);     root.addview(installdb);     steps.put(installsteps.install_database, installdb); 

has idea might cause behaviour? i'm completly stuck. tip appreciated!

you can use enummap instead of hashmap.

a specialized map implementation use enum type keys. of keys in enum map must come single enum type specified, explicitly or implicitly, when map created.

as far code concerned , remember:

1. the hashcode of objects in map should not change once added map. implementation of equals() , hashcode() required.

2. check if put(key,value) object key before get(key)ing value.