I tried run on Windows 7 some old utility that depends on old JRE version.
I have last Java Runtime Environment 1.7.0_79 installed. When I attepmt to start application, I got an error:
"Sivus requires JRE 1.4 or later to run. You can download JRE
from...etc"
Is there a workaround to resolve/fix this or something of that nature?
Program main executable packed in SFX ZIP archive, I extracted files, and found Java file, which makes the check. There is a code:
public static boolean checkJavaVersion(){
boolean ok = false;
String version = System.getProperty("java.version");
if (version.indexOf("1.1") > -1) {
ok = false;
}
else if (version.indexOf("1.2") > -1) {
ok = false;
}
else if (version.indexOf("1.3") > -1) {
ok = false;
}
else if (version.indexOf("1.4") > -1) {
ok = true;
}
else if (version.indexOf("1.5") > -1) {
ok = true;
}
return ok;
}
public static void main(String[] args) {
boolean DEBUG = false;
try {
// check if JRE is over 1.4
if (checkJavaVersion() == false){
JOptionPane.showMessageDialog(
null,
"SiVuS requires JRE 1.4 (or later) to run.\n"
+"You can download the latest JRE from java.sun.com",
"Java Run Time Environment Error",
JOptionPane.WARNING_MESSAGE);
System.exit(1);
}
How to correct this issue and recompile the application again? Will the application that relies on JRE 1.4 work with current JRE?
An example of how I'm doing patches like this.
Fix code - you can add 1.6, 1.7, 1.8 to checkJavaVersion or remove this check at main method.
Put fixed java file in folder that matches package
Compile java file, for example:
call "C:\Program Files (x86)\Java\jdk1.7.0_79\bin\javac.exe" C:\test\mypackage\MyClass.java -cp C:\test\My.jar -source 1.4 -target 1.4
Get compiled class file and replace old file (backup it first)
First of all, I would recommend not using an old tool whose "provenance" is doubtful. Especially, not as a security scanner. Surely, you can find a tool that is newer, and better supported than this one ...
If you wish to proceed (and take a risk) then one approach would be to modify that class, recompile and rebuild the JAR file, as suggested by #Rustam.
Another approach would be to create a simple wrapper class with a main method that called System.setProperty to tweak the value of the "java.version" property, and then called the real main method.
Related
I'm having a problem with loading printer dll. I have a dll file from the printer manufacturer (JniPrinterStatusLib.dll). I wrote code like printer manufacturer suggested. The code is:
package com.printer.test
public class JniPrinterStatus {
static{
System.loadLibrary("JniPrinterStatusLib");
}
public native int GetStatus(String printer);
}
package com.printer.test
public class TestSample {
public static void main(String[] args) {
int status;
String printer = "MY PRINTER";
JniPrinterStatus jps = new JniPrinterStatus();
System.out.println("PRINTER NAME = " + printer);
status = jps.GetStatus(printer);
if (status == -1) {
System.out.println("status = -1");
}
else if (status == 0) {
System.out.println("status = NORMAL");
}
else if ((status & 0x00000080) != 0) {
System.out.println("status = PRINTER_STATUS_OFFLINE");
}
else if ((status & 0x00400000) != 0) {
System.out.println("status = PRINTER_STATUS_DOOR_OPEN");
}
else if ((status & 0x00000010) != 0) {
System.out.println("status = PRINTER_STATUS_PAPER_OUT");
}
else if ((status & 0x00000800) != 0) {
System.out.println("status = PRINTER_STATUS_OUTPUT_BIN_FULL");
}
else if ((status & 0x00000040) != 0) {
System.out.println("status = PRINTER_STATUS_PAPER_PROBLEM");
}
}
}
I used Eclipse to run the code, i put the dll library in the folder project and the error is
PRINTER NAME = MY PRINTER
Exception in thread "main" java.lang.UnsatisfiedLinkError: com.printer.test.JniPrinterStatus.GetStatus(Ljava/lang/String;)I
at com.printer.test.JniPrinterStatus.GetStatus(Native Method)
at com.printer.test.TestSample.main(TestSample.java:10)
If i move the source from the package "com.printer.test" to default package the code works and show:
PRINTER NAME = MY PRINTER
status = -1
I don't know how it's possible. If i compile and run the code from command prompt without package it works.
Where is the problem?
Thank you
From the javadoc for class UnsatisfiedLinkError...
Thrown if the Java Virtual Machine cannot find an appropriate
native-language definition of a method declared native.
That means that function Java_com_printer_test_JniPrinterStatus_GetStatus is not found.
Method loadLibrary in class java.lang.System usually searches the directories listed in the [System] property "java.library.path". For Windows machines, the value of this property is generally the value of the PATH environment variable.
So I suggest printing out the value of that property in your code to see whether it includes the directory containing your DLL. If it doesn't then you need to fix that, either by relocating the DLL or changing the PATH environment variable or launching your java program with the -Djava.library.path=... option. After that you need to check the signature of the native method. Dependency Walker is a tool I use at my work to accomplish this.
EDIT
Having re-read your question, I feel I did not accurately address your question, so let me add...
The default behaviour of Eclipse is to copy resource files, like DLLs, to the output folder. So if you put your DLL in folder src\com\printer\test, it will get copie to folder bin\com\printer\test. My guess is that the current, working directory, i.e. . is in your "java.library.path" which is why it works when your java code is in the default package.
Sorry, actually I wanted to write a comment, but as I'm still low on reputation, I have to try and guess an answer.
There should be no need to recompile the dll - it's just some native code to be invoked.
The java package of the class loading the dll should not make a difference, either.
You have to take care about your system architecture: A 64-bit dll file will fail in a 32-bit JRE and vice versa. Make sure, your JRE architecture matches the dll architecture.
Another thing to take into account is your working directory. Eclipse may use a working directory different from what you used when you ran you program from console.
Last but not least, please have a look at your java.library.path variable.
This page might also help: https://www.chilkatsoft.com/java-loadLibrary-Windows.asp
I covers all the details.
The expected package of the Java classes is hard-coded in the JNI library. In your case, it's the default package.
Let me expand on that. When one implements a native method in a JNI library, one has to create a public C function with a name in the following format:
Java_com_mypackage_MyClass_MyMethod
In other words, the JNI library can't provide methods for the classes in arbitrary packages - only for classes in packages that the JNI library authors had in mind.
In your case, it's the default one. The C function goes Java_JniPrinterStatus_GetStatus. If you call your class MyPrinterStatus, or place it into package com.foobar, the JNI run-time won't be able to associate the C function with the declared Java native method. That's just how JNI was designed.
For Openhab2 there is a binding add-on called RFXCOM. The problem however is that this add-on uses JD2XX which is not compatible with the ARM architecture of the Raspberry Pi.
I have found a Github repository with the source that you can use to compile a *.so file: https://github.com/0x6a77/JD2XX
A little change to the Makefile to use the correct Java path (zulu-8-armhf-embedded instead of (oracle-7).
Running sudo make jni creates a *.so file which I copied to /usr/lib (inside the java library path). However I still get the error that the Raspberry Pi can't open the shared library due to it being 32-bit. How can you compile a shared library that works for ARM with the source provided by the Github repository.
Error message:
java.lang.UnsatisfiedLinkError:
/var/lib/openhab2/tmp/libjd2xx5892592723514582617.so:
/var/lib/openhab2/tmp/libjd2xx5892592723514582617.so: cannot open shared object file:
No such file or directory (Possible cause: can't load IA 32-bit .so on a ARM-bit platform)
The Raspberry Pi has a fresh installation of Openhabian.
Link to the issue on Github: https://github.com/openhab/openhab2-addons/issues/2316#issuecomment-304795652
EDIT:
11:00:52.291 [ERROR] [rnal.discovery.RFXComBridgeDiscovery] - Error occurred during discovery
java.io.IOException: device not found (2)
at jd2xx.JD2XX.listDevices(Native Method)
at jd2xx.JD2XX.listDevicesByDescription(JD2XX.java:785)
at org.openhab.binding.rfxcom.internal.discovery.RFXComBridgeDiscovery.discoverRfxcom(RFXComBridgeDiscovery.java:89)
at org.openhab.binding.rfxcom.internal.discovery.RFXComBridgeDiscovery.startScan(RFXComBridgeDiscovery.java:66)
at org.eclipse.smarthome.config.discovery.AbstractDiscoveryService.startScan(AbstractDiscoveryService.java:199)
at org.eclipse.smarthome.config.discovery.internal.DiscoveryServiceRegistryImpl.startScan(DiscoveryServiceRegistryImpl.java:382)
at org.eclipse.smarthome.config.discovery.internal.DiscoveryServiceRegistryImpl.startScans(DiscoveryServiceRegistryImpl.java:358)
at org.eclipse.smarthome.config.discovery.internal.DiscoveryServiceRegistryImpl.startScan(DiscoveryServiceRegistryImpl.java:216)
at org.eclipse.smarthome.io.rest.core.discovery.DiscoveryResource.scan(DiscoveryResource.java:84)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)[:1.8.0_121]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)[:1.8.0_121]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)[:1.8.0_121]
at java.lang.reflect.Method.invoke(Method.java:498)[:1.8.0_121]
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:160)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)[157:org.glassfish.jersey.core.jersey-common:2.22.2]
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)[157:org.glassfish.jersey.core.jersey-common:2.22.2]
at org.glassfish.jersey.internal.Errors.process(Errors.java:315)[157:org.glassfish.jersey.core.jersey-common:2.22.2]
at org.glassfish.jersey.internal.Errors.process(Errors.java:297)[157:org.glassfish.jersey.core.jersey-common:2.22.2]
at org.glassfish.jersey.internal.Errors.process(Errors.java:267)[157:org.glassfish.jersey.core.jersey-common:2.22.2]
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)[157:org.glassfish.jersey.core.jersey-common:2.22.2]
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)[158:org.glassfish.jersey.core.jersey-server:2.22.2]
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)[155:org.glassfish.jersey.containers.jersey-container-servlet-core:2.22.2]
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)[155:org.glassfish.jersey.containers.jersey-container-servlet-core:2.22.2]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)[155:org.glassfish.jersey.containers.jersey-container-servlet-core:2.22.2]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)[155:org.glassfish.jersey.containers.jersey-container-servlet-core:2.22.2]
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)[155:org.glassfish.jersey.containers.jersey-container-servlet-core:2.22.2]
at com.eclipsesource.jaxrs.publisher.internal.ServletContainerBridge.service(ServletContainerBridge.java:76)[10:com.eclipsesource.jaxrs.publisher:5.3.1.201602281253]
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:812)[81:org.eclipse.jetty.servlet:9.2.19.v20160908]
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:587)[81:org.eclipse.jetty.servlet:9.2.19.v20160908]
at org.ops4j.pax.web.service.jetty.internal.HttpServiceServletHandler.doHandle(HttpServiceServletHandler.java:71)[172:org.ops4j.pax.web.pax-web-jetty:4.3.0]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577)[79:org.eclipse.jetty.security:9.2.19.v20160908]
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.ops4j.pax.web.service.jetty.internal.HttpServiceContext.doHandle(HttpServiceContext.java:287)[172:org.ops4j.pax.web.pax-web-jetty:4.3.0]
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515)[81:org.eclipse.jetty.servlet:9.2.19.v20160908]
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.ops4j.pax.web.service.jetty.internal.JettyServerHandlerCollection.handle(JettyServerHandlerCollection.java:80)[172:org.ops4j.pax.web.pax-web-jetty:4.3.0]
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.eclipse.jetty.server.Server.handle(Server.java:499)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:257)[80:org.eclipse.jetty.server:9.2.19.v20160908]
at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:544)[72:org.eclipse.jetty.io:9.2.19.v20160908]
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635)[83:org.eclipse.jetty.util:9.2.19.v20160908]
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555)[83:org.eclipse.jetty.util:9.2.19.v20160908]
at java.lang.Thread.run(Thread.java:745)[:1.8.0_121]
11:01:02.868 [WARN ] [e.sshd.server.channel.ChannelSession] - Unknown pty opcode value: 42
In the JD2XX.java file, you can see the mechanism how to load a dll, so or some other type of library depending on OS.
static {
String dataModel = System.getProperty("sun.arch.data.model");
String osName = System.getProperty("os.name").toLowerCase();;
StringBuilder lib = new StringBuilder("/jni/");
if (osName.contains("win"))
lib.append("win/");
else if (osName.contains("linux"))
lib.append("linux/");
else if (osName.contains("mac"))
lib.append("mac/");
else
throw new UnsatisfiedLinkError("Loading JD2XX JNI: Unsupported operating system ("+osName+")");
if (dataModel.equals("32"))
lib.append("x86_32/");
else if (dataModel.equals("64"))
lib.append("x86_64/");
else
throw new UnsatisfiedLinkError("Loading JD2XX JNI: Unknown runtime data model ("+dataModel+")");
if (osName.contains("win"))
lib.append("jd2xx.dll");
else if (osName.contains("linux"))
lib.append("libjd2xx.so");
else if (osName.contains("mac"))
lib.append("libjd2xx.jnilib");
try {
NativeUtils.loadLibraryFromJar(lib.toString());
} catch (IOException e) {
throw new UnsatisfiedLinkError(e.getMessage());
}
}
The loadLibraryFromJar method from NativeUtils creates temp directory and copy the right library for OS to temp directory then call the System.load method eventually.
So, I think you should modify this part of source code like the code as follows, if possible.
static
{
System.load("/var/lib/openhab2/tmp/libjd2xx5892592723514582617.so");
}
or
static
{
System.load("/usr/lib/libjd2xx5892592723514582617.so");
}
There are several ways to make this job work re-setting the 'java.library.path' order to indicate the /usr/lib directory first then use the code below.
Or you can rename the library name, libjd2xx5892592723514582617.so to libjd2xx.so in the /usr/lib which is usually in the 'LD_LIBRARY_PATH' variable.
then, our code in the JD2XX.java can be used instead,
static
{
System.loadLibrary("jd2xx");
}
I think it works..
Running the "Update current installation" option, how do I obtain the version info from the prior installation? I've been through the API and the closest thing I've seen is the public static interface ApplicationRegistry.ApplicationInfo.
Edit
This is how I am currently going about it. It works but am not sure if this is the most feasible method.
import com.install4j.api.ApplicationRegistry;
ApplicationRegistry.ApplicationInfo[] AppInfo = ApplicationRegistry.getApplicationInfoById(context.getApplicationId());
return AppInfo[0].getVersion();
You could use the
static ApplicationRegistry.ApplicationInfo getApplicationInfoByDir(java.io.File dir)
Checks if the specified directory contains an application installed by install4j and retrieves information about it.
This will return a ApplicationInfo instead of the ApplicationInfo[].
As an example, the following script checks if the same version is already installed:
// The value returned by context.getInstallationDirectory() will be
// the last installation directory if the user has already installed the application
ApplicationRegistry.ApplicationInfo applicationInfo =
ApplicationRegistry.getApplicationInfoByDir(context.getInstallationDirectory());
if (applicationInfo == null) {
// The application has never been installed before
return true;
}
// The version of this installer is contained in a system installer variable
String myVersion = (String)context.getVariable("sys.version");
if (applicationInfo.getVersion().equals(myVersion)) {
// In that case the current version is already installed.
Util.showErrorMessage("The current version is already installed in this directory");
// By returning "false", the action will fail and the installer will quit.
// Note that you have to set the "Failure strategy" property of your
// "Run script" action to "Quit on error", otherwise the installer will continue.
return false;
} else {
return true;
}
This could for example be used in a "Run script" action in the "Startup" node of the installer.
Is there a way to check if a specific program is installed on Windows using Java?
I'm trying to develop a Java program that automatically creates zip archives by using the code line command from 7-Zip.
So, I would like to check in Java if on my windows OS '7-Zip' is already installed. No check for running apps or if OS is Windows or Linux. I want to get a bool (true/false) if '7-Zip' is installed on Windows.
The library Apache Commons has a class called SystemUtils - full documentation is available at https://commons.apache.org/proper/commons-lang/javadocs/api-2.6/org/apache/commons/lang/SystemUtils.html.
In this library you have the following static boolean properties at your disposal:
SystemUtils.IS_OS_LINUX
SystemUtils.IS_OS_WINDOWS
The unix-like solution would be to simply try to run the program with --version flag (on windows probably the /? or - like in the 7zip case - without any at all) and check whether it fails, or what the return code will be.
Something like:
public boolean is7zipInstalled() {
try {
Process process = Runtime.getRuntime().exec("7zip.exe");
int code = process.waitFor();
return code == 0;
} catch (Exception e) {
return false;
}
}
I assume that you're talking about Windows. As Java is intended to be a platform-independent language and the way how to determine it differs per platform, there's no standard Java API to check that. You can however do it with help of JNI calls on a DLL which crawls the Windows registry. You can then just check if the registry key associated with the software is present in the registry. There's a 3rd party Java API with which you can crawl the Windows registry: jRegistryKey.
Here's an SSCCE with help of jRegistryKey:
package com.stackoverflow.q2439984;
import java.io.File;
import java.util.Iterator;
import ca.beq.util.win32.registry.RegistryKey;
import ca.beq.util.win32.registry.RootKey;
public class Test {
public static void main(String... args) throws Exception {
RegistryKey.initialize(Test.class.getResource("jRegistryKey.dll").getFile());
RegistryKey key = new RegistryKey(RootKey.HKLM, "Software\\Mozilla");
for (Iterator<RegistryKey> subkeys = key.subkeys(); subkeys.hasNext();) {
RegistryKey subkey = subkeys.next();
System.out.println(subkey.getName()); // You need to check here if there's anything which matches "Mozilla FireFox".
}
}
}
If you however intend to have a platformindependent application, then you'll also have to take into account the Linux/UNIX/Mac/Solaris/etc. (in other words: anywhere where Java is able to run) ways to detect whether FF is installed. Else you'll have to distribute it as a Windows-only application and do a System#exit() along with a warning whenever System.getProperty("os.name") is not Windows.
Sorry, I don't know how to detect in other platforms whether FF is installed or not, so don't expect an answer from me for that ;)
This is the second time I've tried to use the PrintWriter#printf method, and I get this error message:
The method printf(String, Object[]) in the type PrintStream is not applicable for the argument (String, String)
The code I'm using has two classes.
This is the first class:
class apples4 {
public static void main(String[] args) {
tuna4 tuna4Object = new tuna4("Kelsey");
tuna4Object.saying();
}
}
This is the second class:
public class tuna4 {
private String girlName;
public tuna4(String name) {
girlName=name;
}
public void setName(String name) {
girlName=name;
}
public String getName() {
return girlName;
}
public void saying(){
System.out.printf("Your first girlfriend was %s\n", getName() );
}
}
Check your compliance level...
PrintStream#printf method is available since Java SE 5. Looks like your code is being compiled/evaluated by Java 4 or prior.
Review your JDK installation and/or your IDE settings about how it is compiling/evaluating your code.
By the way, if using Eclipse and Java 8, Eclipse needs a plugin to recognize Java 8 applications, so by default the evaluator will downgrade your project to Java 1.4. This happened to me and I solved it by installing an update in Eclipse Kepler. Eclipse Luna (latest Eclipse version)says that it supports Java 8, but didn't work for me (not sure if I followed the right steps or did something wrong, but went back to Kepler and works fine).
It might sound weird, but you can cast the return value of your getName() method to Object:
System.out.printf("Your first girlfriend was %s\n", (Object) getName());
Or (to create the requested array) even
System.out.printf("Your first girlfriend was %s\n", new Object[] {(Object) getName()} );
could help.
I'm sorry about my previous post saying I had the same problem, I didn't read the "before you post read this" dialog box that says don't do that. Well, after a lot of time looking around for the answer, I figured it out myself. In Preferences->Java->Compiler box, there is a button in the top left corner called "Configure Project Specific Settings...". Click it and either change the compliance level to >= Java 1.5, or turn it off. Boom, fixed.
you might need to change the execution environment if it's not already java SE 1.8
it might be CDC or sth else , so u need to change it to java SE 1.8
details in picture 1.expand ur project then 2.right click on JRE System Library and choose properties finally 3. if the environment is not java SE 1.8 ,change it to become so