A Technical I.T./DevOps Blog
Problem scenario
You want to write a basic Java program to test it out. How do you write a program to accept user input, specifically a number, and print it back to the screen (using the integer data type)?
Solution
1. Install the Java Development Kit if you have not installed it yet. If you are not sure you have it, run javac -version.
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Problem scenario
You have compiled the source code of a Java program into bytecode (with a .class extension). You try to run it (execute the bytecode) with a javac command (javac HelloWorld), but you get “error: Class names, ‘HelloWorld’, are only accepted if annotation processing is explicitly requested
1 error “
What should you do?
Solution
Run it with the java command like this (with no “.class” extension): java HelloWorld
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Continue reading “How Do You Run a Java Program That Has Compiled Successfully?”
Problem scenario
You run a Java program and receive “java.lang.classnotfoundexception oracle.jdbc.driver.oracledriver”. You need to get a program working despite reading that this driver has been deprecated. What should you do?
Solution
1. Find the JRE/lib/ext directory.
2. Place an ojdbc14.jar file (e.g., downloaded from Oracle.com or some trustworthy website) in that directory.
3. Without recompiling your program, run the Java program again.
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Problem scenario
You have no desktop GUI and a limited ability to install new applications other than the Java compiler. You are not be allowed to install a SQL command line client such as sqlconnect or a utility such as tnsping. What should you do to test the credentials, server name and port number to ensure they work to allow access to an Oracle database?
Solution
The overview is to use a Java program with the code provided below.
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Problem scenario
You get an error such as this on a Linux server:
“Caused by: java.lang.AbstractMethodError: Method oracle/jdbc/driver/OraclePrepreadStatementWrapper.setBinaryStream (IL java/io/InputStream;)V is abstract at oracle.jdbc.driver.OraclePreparedStatementWrapper.setBinaryStream (OraclePreparedStatementWrapper.java)”
What should you do?
Possible Solution #1
If you are doing Java coding, have you imported the packages needed for the line of Java code that is throwing this error?
Possible Solution #2
If you are using JBoss,
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Problem scenario
You run spark-shell in a Debian distribution of Linux (e.g., Ubuntu) but you receive this error:
Error: A JNI error has occurred, please check your installation and try again
Exception in thread “main” java.lang.ArrayIndexOutOfBoundsException: 64
at java.util.jar.JarFile.match(java.base@9-internal/JarFile.java:983)
at java.util.jar.JarFile.checkForSpecialAttributes(java.base@9-internal/JarFile.java:1017)
at java.util.jar.JarFile.isMultiRelease(java.base@9-internal/JarFile.java:399)
at java.util.jar.JarFile.getEntry(java.base@9-internal/JarFile.java:524)
at java.util.jar.JarFile.getJarEntry(java.base@9-internal/JarFile.java:480)
at jdk.internal.util.jar.JarIndex.getJarIndex(java.base@9-internal/JarIndex.java:114)
at jdk.internal.loader.URLClassPath$JarLoader$1.run(java.base@9-internal/URLClassPath.java:640)
at jdk.internal.loader.URLClassPath$JarLoader$1.run(java.base@9-internal/URLClassPath.java:632)
at java.security.AccessController.doPrivileged(java.base@9-internal/Native Method)
at jdk.internal.loader.URLClassPath$JarLoader.ensureOpen(java.base@9-internal/URLClassPath.java:631)
at jdk.internal.loader.URLClassPath$JarLoader.<init(java.base@9-internal/URLClassPath.java:606)
at jdk.internal.loader.URLClassPath$3.run(java.base@9-internal/URLClassPath.java:386)
at jdk.internal.loader.URLClassPath$3.run(java.base@9-internal/URLClassPath.java:376)
at java.security.AccessController.doPrivileged(java.base@9-internal/Native Method)
at jdk.internal.loader.URLClassPath.getLoader(java.base@9-internal/URLClassPath.java:375)
at jdk.internal.loader.URLClassPath.getLoader(java.base@9-internal/URLClassPath.java:352)
at jdk.internal.loader.URLClassPath.getResource(java.base@9-internal/URLClassPath.java:218)
at jdk.internal.loader.BuiltinClassLoader$3.run(java.base@9-internal/BuiltinClassLoader.java:463)
at jdk.internal.loader.BuiltinClassLoader$3.run(java.base@9-internal/BuiltinClassLoader.java:460)
at java.security.AccessController.doPrivileged(java.base@9-internal/Native Method)
at jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(java.base@9-internal/BuiltinClassLoader.java:459)
at jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(java.base@9-internal/BuiltinClassLoader.java:406)
at jdk.internal.loader.BuiltinClassLoader.loadClass(java.base@9-internal/BuiltinClassLoader.java:364)
at jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(java.base@9-internal/ClassLoaders.java:184)
at java.lang.ClassLoader.loadClass(java.base@9-internal/ClassLoader.java:419)
at sun.launcher.LauncherHelper.loadMainClass(java.base@9-internal/LauncherHelper.java:585)
at sun.launcher.LauncherHelper.checkAndLoadMain(java.base@9-internal/LauncherHelper.java:497)
How do you solve this?
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Continue reading “How Do You Troubleshoot the Spark-Shell Error “A JNI error has occurred”?”
Problem scenario
You want to install Maven with a script. You want the script to work regardless of what distribution of Linux you are using (e.g., Ubuntu/Debian, RedHat (including CentOS/Fedora), or SUSE). How do you write a script to install the latest version of Maven?
Solution
Update: This script was updated on 9/23/19.
1. Create this file in /tmp/ and call it maven.sh.
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Continue reading “How Do You Install Maven on Any Type of Linux?”
Problem scenario
You want a Bash script to install Java on Linux. (If you want to install Java on Windows, see this posting.) You want it to work regardless if it is a Linux that is part of the Debian/Ubuntu family, RedHat family (e.g., CentOS/Fedora), or SUSE. What do you do to write a universal script to make it easy for other systems administrators to install Java (or potentially automate the process across several servers)?
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Continue reading “How Do You Install Java on Any Type of Linux with a Script?”
Problem scenario
You want to list the instrumented JVMs on your Linux OS. Therefore you want to run the command jps. What package(s) do you need to install?
Solution
For CentOS/RedHat/Fedora run this:
sudo yum -y install java-1.8.0-openjdk-devel
For Linux SUSE run this:
sudo zypper -n install java-1_8_0-openjdk-devel
For Ubuntu/Debian Linux run this:
sudo apt-get -y install openjdk-8-jdk-headless default-jre
If you want to learn more about the Java process status tool,
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Problem scenario
You need to install Java version 8 on a Windows 64 bit server. How do you do this with PowerShell?
Solution
1. Open PowerShell ISE as Administrator.
2. Run this script:
# This is a modified version of PowerShell code taken from this site:
# https://skarlso.github.io/2015/06/30/powershell-can-also-be-nice-or-installing-java-silently-and-waiting/
$JDK_VER=”1u151″
$JDK_FULL_VER=”8u151-b12″
$JDK_PATH=”1.8.0_151″
$source86 = “http://download.oracle.com/otn-pub/java/jdk/$JDK_FULL_VER/jdk-$JDK_VER-windows-i586.exe”
$source64 = “http://javadl.oracle.com/webapps/download/AutoDL?BundleId=230542_2f38c3b165be4555a1fa6e98c45e0808”
$destination86 = “C:\Program Files (x86)\$JDK_VER-x86.exe”
$destination64 = “C:\Program Files (x86)\$JDK_VER-x64.exe”
$client = new-object System.Net.WebClient
$cookie = “oraclelicense=accept-securebackup-cookie”
$client.Headers.Add([System.Net.HttpRequestHeader]::Cookie,
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Continue reading “How Do You Install Java Version 8 on a Windows 64 Bit Server with PowerShell?”