java - My lifecycle codes not compiling -


for each callback events (oncreate(), onstart()... ), record callback event triggered in log(use log.d); message written log should defined in “strings.xml” , getresources.getstring() should used retrieve message

implement onsaveinstancestate , onrestoreinstancestate – track number of times onsaveinstancestate being called, in onrestoreinstancestate, print value log file

tag “log” statement should defined in strings.xml , set using getresources.getstring()

package com.csci235labs.rob_lifecycles;  import android.os.bundle; import android.support.v7.app.appcompatactivity; import android.util.log;  public class mainactivity extends appcompatactivity {  string tag = getresources().getstring(r.string.app_name); //logcat tag string activitystate; int instancetimes; //number of times instance called string act_keys;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      //recover instance state     if(savedinstancestate!=null)     {         activitystate = savedinstancestate.getstring(act_keys);     }     else     {         instancetimes=0;         act_keys="";     }      setcontentview(r.layout.activity_main);   }  @override protected void onrestoreinstancestate(bundle savedinstancestate) {     super.onrestoreinstancestate(savedinstancestate); }  @override protected void onsaveinstancestate(bundle outstate) {     instancetimes++;     activitystate=string.valueof(instancetimes);      outstate.putstring(act_keys,activitystate);      super.onsaveinstancestate(outstate); }   @override protected void onstart() {     super.onstart();     //logs event message     string eventmessage=getresources().getstring(r.string.on_start_str);     log.d(tag,eventmessage); }  @override protected void onresume() {     super.onresume();     //logs event message     string eventmessage=getresources().getstring(r.string.on_resume_str);     log.d(tag,eventmessage); }  @override protected void onpause() {     super.onpause();     //logs event message     string eventmessage=getresources().getstring(r.string.on_pause_str);     log.d(tag,eventmessage); }  @override protected void onstop() {     super.onstop();     //logs event message     string eventmessage=getresources().getstring(r.string.on_stop_str);     log.d(tag,eventmessage); }  @override protected void ondestroy() {     super.ondestroy();     //logs event message     string eventmessage=getresources().getstring(r.string.on_destroy_str);     log.d(tag,eventmessage);  } }

xml file:

<resources>   <string name="app_name">rob_lifecycles</string>   <string name="app_str">teststring</string>   <string name="on_create_str">oncreate() method</string>   <string name="on_start_str">onstart() method</string>   <string name="on_resume_str">onresume() method</string>   <string name="on_pause_str">onpause() method</string>   <string name="on_stop_str">onstop() method</string>   <string name="on_destroy_str">ondestroy() method</string>   <string name="action_settings">settings</string> </resources>

remove tag initialization outside , move oncreate() because context.getresources() give null pointer exception in case

public class mainactivity extends appcompatactivity {  string tag; string activitystate; int instancetimes; //number of times instance called string act_keys;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);       setcontentview(r.layout.activity_main);     tag = getresources().getstring(r.string.app_name); //logcat tag     //recover instance state     if(savedinstancestate!=null)     {        activitystate = savedinstancestate.getstring(act_keys);     }     else     {        instancetimes=0;        act_keys="";     } }

Comments

Post a Comment

Popular posts from this blog

Sort a complex associative array in PHP -

this question has answer here: php sort array subarray value 5 answers i have associative array in php like: $newarray1 = array ( [producta] => array ( [link] => http://sanjosespartan.com/blog/products/agile-java-development/ [visitcount] => 4 ) [productd] => array ( [link] => http://sanjosespartan.com/blog/products/intro-to-go/ [visitcount] => 1 ) [productg] => array ( [link] => http://sanjosespartan.com/blog/products/node-js-for-developers/ [visitcount] => 1 ) [productb] => array ( [link] => http://sanjosespartan.com/blog/products/beginning-mysql/ [visitcount] => 1 ) [productc] => array ( [link] => http://sanjosespartan.com/blog/products/computer-networks/ [visitcount] => 1 ) ...
Read more

vb.net - How to ignore if a cell is empty nothing -

how use roscolor() ignore value (like empty cell) ? color row if value upper 5 when there nothing in cell, want ignore roscolor() apply, how? public sub roscolor() integer = 0 quotedatagridview1.rows.count() - 1 step +1 dim val integer val = quotedatagridview1.rows(i).cells(3).value if val = vbempty quotedatagridview1.rows(i).defaultcellstyle.backcolor = color.white elseif val < 5 quotedatagridview1.rows(i).defaultcellstyle.backcolor = color.red elseif val > 5 , val < 10 quotedatagridview1.rows(i).defaultcellstyle.backcolor = color.lightyellow end if next end sub you can check empty value following public sub roscolor() integer = 0 quotedatagridview1.rows.count() - 1 step +1 dim val = quotedatagridview1.rows(i).cells(3).value if isdbnull(val) or val nothing quotedatagridview1.rows(i).defaultcellstyle.backcolor = color.white ...
Read more

recursion - Can every recursive algorithm be improved with dynamic programming? -

i first year undergraduate csc student looking competitive programming. recursion involves defining , solving sub problems. understand, top down dynamic programming (dp) involves memoizing solutions sub problems reduce time complexity of algorithm. can top down dp used improve efficiency of every recursive algorithm overlapping sub problems? dp fail work , how can identify this? the short answer is: yes. however, there constraints. obvious 1 recursive calls must overlap. i.e. during execution of algorithm, recursive function must called multiple times same parameters. lets truncate recursion tree memoization. can use memoization reduce number of calls. however, reduction of calls comes price. need store results somewhere. next obvious constraint need have enough memory. comes not-so obvious constraint. memory access requires time. first need find result stored , maybe copy location. in cases, might faster let recursion calculate result instead of loading somewher...
Read more