Android应用程序崩溃从长时间闲置回来

Question

我是Android的新手。用户从长时间闲置返回时，我的应用程序崩溃我已阅读Android应用生命周期并调试应用。当用户从长时间闲置状态返回时，看起来我的应用程序在onCreate方法中崩溃。下面是我的onCreate代码。它获得从先前活动设置的全局变量（CustomerName）。然后，从基于CustomerName的SQLLite中提取数据以显示数据。我认为Android VM已经在用户返回活动时终止了该过程，但我认为当onCreate再次调用时该过程应该有效。任何帮助将不胜感激。

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.activity_report_review);
    intialize();
    adddynamiccheckboexes();

    //Initialize
    metrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metrics);
    panelWidth = (int) ((metrics.widthPixels)*0.75);

    headerPanel = (RelativeLayout) findViewById(R.id.header);
    headerPanelParameters = (LinearLayout.LayoutParams) headerPanel.getLayoutParams();
    headerPanelParameters.width = metrics.widthPixels;
    headerPanel.setLayoutParams(headerPanelParameters);

    menuPanel = (RelativeLayout) findViewById(R.id.menuPanel);
    menuPanelParameters = (FrameLayout.LayoutParams) menuPanel.getLayoutParams();
    menuPanelParameters.width = panelWidth;
    menuPanel.setLayoutParams(menuPanelParameters);

    slidingPanel = (LinearLayout) findViewById(R.id.slidingPanel);
    slidingPanelParameters = (FrameLayout.LayoutParams) slidingPanel.getLayoutParams();
    slidingPanelParameters.width = metrics.widthPixels;
    slidingPanel.setLayoutParams(slidingPanelParameters);

    CustomerName = ((GlobalVariables) this.getApplication()).getSomeVariable();
    //Check to see if CustName exist.  If not, go to Main screen
    CustomerName.trim();
    if (CustomerName.equals("null") || CustomerName.equals("")){
        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
        return;
    }

    assessHelper = new AssessmentDBAdaptor(this);
    assessHelper.open();
    String fCustomerName = CustomerName;
    fCustomerName = fCustomerName.replaceAll("''", "'");
    fCustomerName = fCustomerName.replaceAll("'", "''");
    Cursor AssessInfo = assessHelper.fetchAssessmentByExactName(fCustomerName);
    if (AssessInfo.moveToFirst()){
        City = AssessInfo.getString(AssessInfo.getColumnIndexOrThrow("City")).toString();
        State = AssessInfo.getString(AssessInfo.getColumnIndexOrThrow("State")).toString();
        AssessDate = AssessInfo.getString(AssessInfo.getColumnIndexOrThrow("CreatedDate")).toString();
        TA_Name = AssessInfo.getString(AssessInfo.getColumnIndexOrThrow("PresentedBy")).toString();       
        CustEmail = AssessInfo.getString(AssessInfo.getColumnIndexOrThrow("Email")).toString();       
    }else{
        Toast.makeText(getApplicationContext(), "Error: Unable to retrieve Assessment Information", Toast.LENGTH_SHORT).show();
    }

    ppHelper = new DBPlantPhoto(this);
    ppHelper.open();
    fCustomerName = CustomerName;
    fCustomerName = fCustomerName.replaceAll("''", "'");
    fCustomerName = fCustomerName.replaceAll("'", "''");
    Cursor sPP = ppHelper.fetchPlantPhotoByAssessment(fCustomerName);
    if (sPP.moveToFirst()){
        FileName = sPP.getString(sPP.getColumnIndexOrThrow("FileName")).toString();
    }else{
                //Toast.makeText(getApplicationContext(), "Error: Unable to retrieve Plant Photo", Toast.LENGTH_SHORT).show();
    }

    //Tien
    dbBulletHelper = new DBSlideBullet(this);
    dbBulletHelper.open();

    fCustomerName = CustomerName;
    fCustomerName = fCustomerName.replaceAll("''", "'");
    fCustomerName = fCustomerName.replaceAll("'", "''");
  Cursor cAssess = dbBulletHelper.fetchSlideInfobyCateandAssess("Best Practice Summary", fCustomerName);
if (cAssess.moveToFirst()){
      //Exist
    }else{
     //Not Exist
        DBSlideBullet entry = new DBSlideBullet(ReportReview.this); //call upon database pass in context of this class
        entry.open();
        entry.CreateEntry("Best Practice Summary", "Best Practice Summary", "1", " ", "", "" ,"" ,"", "", "", "", "", "", "", "", "", "", "", "", "", CustomerName, "" ); //Create Method in order to pass information into 
        entry.close();
    }
    cAssess = dbBulletHelper.fetchSlideInfobyCateandAssess("Current Product Overview", fCustomerName);
    if (cAssess.moveToFirst()){
      //Exist
    }else{
     //Not Exist
        DBSlideBullet entry = new DBSlideBullet(ReportReview.this); //call upon database pass in context of this class
        entry.open();
        entry.CreateEntry("Current Product Overview", "Current Product Overview", "1", " ", "", "" ,"" ,"", "", "", "", "", "", "", "", "", "", "", "", "", CustomerName, "" ); //Create Method in order to pass information into 
        entry.close();
    }
    cAssess = dbBulletHelper.fetchSlideInfobyCateandAssess("Major Improvement Areas", fCustomerName);
    if (cAssess.moveToFirst()){
      //Exist
    }else{
     //Not Exist
        DBSlideBullet entry = new DBSlideBullet(ReportReview.this); //call upon database pass in context of this class
        entry.open();
        entry.CreateEntry("Major Improvement Areas", "Major Improvement Areas - Review", "1", " ", "", "" ,"" ,"", "", "", "", "", "", "", "", "", "", "", "", "", CustomerName, "" ); //Create Method in order to pass information into 
        entry.close();
    }
    cAssess = dbBulletHelper.fetchSlideInfobyCateandAssess("Next Steps", fCustomerName);
    if (cAssess.moveToFirst()){
      //Exist
    }else{
     //Not Exist
        DBSlideBullet entry = new DBSlideBullet(ReportReview.this); //call upon database pass in context of this class
        entry.open();
        entry.CreateEntry("Next Steps", "Next Steps", "1", " ", "", "" ,"" ,"", "", "", "", "", "", "", "", "", "", "", "", "", CustomerName, "" ); //Create Method in order to pass information into 
        entry.close();
    }


    Bundle gotBasket = getIntent().getExtras();
    Storage = gotBasket.getStringArray("Storage");
    ProductApp = gotBasket.getStringArray("ProductApp");
    StandardProc = gotBasket.getStringArray("StandardProc");
    Training = gotBasket.getStringArray("Training");
    Contamination = gotBasket.getStringArray("Contamination");
    OilCondition = gotBasket.getStringArray("OilCondition");
    ReliabilityAssessment = gotBasket.getStringArray("ReliabilityAssessment");
    Planning = gotBasket.getStringArray("Planning");

    //Get User and Customer Email
    upHelper = new UserProfileDBAdaptor(this);
    upHelper.open();
    Cursor cUP = upHelper.fetchAllUserProfile();
    cUP.moveToFirst();
    UserEmail = cUP.getString(cUP.getColumnIndexOrThrow("Email")).toString();
    upHelper.close();

}

Answer 1

android可能会从内存中丢弃整个应用程序（即如果需要内存）。

这样，变量CustomerName的内容可能为null，调用trim（）方法可能会导致nullpionterexception。

CustomerName = ((GlobalVariables) this.getApplication()).getSomeVariable();
CustomerName.trim();