How to run a single applications(JShell) on JDK 9, and all other on JDK 8?

Question

I am trying to work with jshell of Java 9. So for that i installed the JDK 9 on my Mac, where i already had the JDK 8 installed.

All my projects, workspaces, Hadoop, Spark and dependent APIs are using JDK 8. So for the current scenario, i can not move all my projects to work with JDK 9.

So what i want is a small utility or a smart way to switch between JDK 8 and JDK 9 on demand basis.

For the time being, what i am doing is:

1. Open a terminal.

   biz=data.frame(
   
       year=query1$YEAR,
       ProdNm=query1$PROD_NM,
       Total = as.numeric(as.character(query1$TOTAL)),
       Sold_that_day = query1$QTY,
       Month = query1$MONTHNAME,
       Weekand= query1$WEEKNAME,
       AreaName=query1$AREA_NAME,
       Manufacturer=query1$MFG,
       stringsAsFactors = FALSE
     )
   
   
     # Total sales By year In  2017 #
   
   
       totalsales="select year(RETAIL_STR_SALES_DETAIL.SALE_DATE) as YEAR,
         monthname(RETAIL_STR_SALES_DETAIL.SALE_DATE) AS MONTHNAME
         ,round(sum(RETAIL_STR_SALES_DETAIL.total),2) as TOTAL
   
         from retail_str_sales_detail where year(RETAIL_STR_SALES_DETAIL.SALE_DATE)='2017'
         group by year(RETAIL_STR_SALES_DETAIL.SALE_DATE),
         monthname(RETAIL_STR_SALES_DETAIL.SALE_DATE)";
   
   
         totalsalesbyyear <- fetch(dbSendQuery(conn,totalsales), -1)
   
   
   
             bizmonthly=data.frame(
   
                   MonthName=factor(totalsalesbyyear$MONTHNAME,levels = month.name),
                   Year=totalsalesbyyear$YEAR,
                   MonthTotal=as.numeric(as.character(totalsalesbyyear$TOTAL))
                 )
   
                 print(bizmonthly)
   

2. Set the JAVA_HOME temporarily to jdk 9

   kv:micro-tab karan.verma$ echo $JAVA_HOME
   /Library/Java/JavaVirtualMachines/jdk1.8.0_144.jdk/Contents/Home
   

3. start the jshell

   kv:Home karan.verma$ export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk-9.0.1.jdk/Contents/Home
   

4. close the terminal when done. That means, the global JAVA_HOME works now.

   kv:Home karan.verma$ jshell
      |  Welcome to JShell -- Version 9.0.1
      |  For an introduction type: /help intro
   

So, my question is, Is there is any better approach to do it? Or this is the a good practice to do such kind of things? Please suggest.

Answer 1

您可以编写脚本。重置环境并在路径中启动jshell。

           GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestEmail()
                .build();
        mGoogleSignInClient = GoogleSignIn.getClient(fragLogin.this._main, gso);


mSignInGoogle0.setOnClickListener(new OnClickListener()
        {
            @Override
            public void onClick(View view)
            {
                Intent signInIntent = mGoogleSignInClient.getSignInIntent();
                startActivityForResult(signInIntent, RC_SIGN_IN);

            }
        });

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    // Result returned from launching the Intent from GoogleSignInClient.getSignInIntent(...);
    if (requestCode == RC_SIGN_IN) {
        // The Task returned from this call is always completed, no need to attach
        // a listener.
        Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
        handleSignInResult(task);
    }
}


private void handleSignInResult(Task<GoogleSignInAccount> completedTask) {
    try {
        GoogleSignInAccount account = completedTask.getResult(ApiException.class);

        // Signed in successfully, show authenticated UI.
        if (account != null)
        {
            mPasswordView.setVisibility(View.GONE);
            mPasswordView.setVisibility(View.GONE);
        }
        updateUI(account);
    } catch (ApiException e) {
        e.printStackTrace();
        // The ApiException status code indicates the detailed failure reason.
        // Please refer to the GoogleSignInStatusCodes class reference for more information.
        Log.w(TAG, "signInResult:failed code=" + e.getStatusCode());
        lib.ShowMessage(getContext(), getString(R.string.googleloginnotsuccessfull) + "\n" + getString(R.string.ErrorCode) + GoogleSignInStatusCodes.getStatusCodeString(e.getStatusCode()) + ":" + e.getStatusCode(), getString(R.string.Error));
        updateUI(null);
    }
}

Answer 2

这是我解决问题的方法：

1. 卸载JDK 9，安装jdk 8，然后安装jdk 9。

2. 为版本8和9添加相应的JAVA_HOME路径。为其设置别名，并将Java 8设置为默认JDK。

   export JAVA_8_HOME=$(/usr/libexec/java_home -v1.8)
   export JAVA_9_HOME=$(/usr/libexec/java_home -v1.9)
   
   alias java8='export JAVA_HOME=$JAVA_8_HOME'
   alias java9='export JAVA_HOME=$JAVA_9_HOME'
   
   #default java8
   export JAVA_HOME=$JAVA_8_HOME
   

3. 现在只需使用别名设置Java 8或Java 9即可在版本之间进行切换，如下所示：

   java8
   java9