Update: I don't know why this solution is not work any more ( I just tested on Android 23). Please use the solution of Saurabh PareekSaurabh Pareek instead. Here it is:
InputMethodManager imm = (InputMethodManager) getSystemService(Activity.INPUT_METHOD_SERVICE);
//Hide:
imm.toggleSoftInput(InputMethodManager.HIDE_IMPLICIT_ONLY, 0);
//Show
imm.toggleSoftInput(InputMethodManager.SHOW_IMPLICIT, 0);
Old answer:
//Show soft-keyboard:
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
//hide keyboard :
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);