CODEWITHSUNDEEP
java
Dangling Cruze
Dangling Cruze

Reputation: 3443

Autoboxing can't convert an int to an Integer

I am a complete beginner and I'm trying to learn java. I read about the concept of Autoboxing and Unboxing here.

I am working on java version 1.8.0_05 and using Eclipse.

The code is :

class Test {
    public static void main(String[] args) {
        Integer iob = 100; // shows error -> Type mismatch: Cannot convert from int to Integer
    }
}

Thanks for the help.

Upvotes: 8

Views: 11442

Answers (3)

Federico Piazza
Federico Piazza

Reputation: 31035

Autoboxing feature is available since Java 1.5.

Make sure that you are running at least Java 1.5.

Otherwise you need new Integer(100) or Integer.valueOf(100). Or just declare it as int instead of Integer.

What you can do is to check the PATH and JAVA_HOME using:

Object obj = System.getenv();
System.out.println(obj);

You should get an output like:

{JAVA_MAIN_CLASS_5612=org.eclipse.jdt.internal.junit.runner.RemoteTestRunner, SHELL=/bin/bash, TMPDIR=/var/folders/zw/n554nzl151sgtr5rqftblcjm0000gn/T/, com.apple.java.jvmMode=client, __CF_USER_TEXT_ENCODING=0x1F5:0:0, APP_ICON_5439=../Resources/sts.icns, PATH=/usr/bin:/bin:/usr/sbin:/sbin:/Users/fede/jdk1.8/bin, JAVA_HOME=/Users/fede/jdk1.8/, USER=fede, com.apple.java.jvmTask=CommandLine_Manual.java, HOME=/Users/fede, LOGNAME=fede, Apple_PubSub_Socket_Render=/tmp/launch-5UzUjs/Render, SSH_AUTH_SOCK=/tmp/launch-2okgJL/Listeners, __CHECKFIX1436934=1, JAVA_STARTED_ON_FIRST_THREAD_5439=1}

That can help figuring out what is happening

Upvotes: 0

Ryan J
Ryan J

Reputation: 8323

You need to have your language level set to at least 1.5/5.0 to take advantage of autoboxing/unboxing.

Change your settings in Project --> Properties --> Java Compiler, chances are, it's not set to the right level.

Note this is NOT directly tied to the version of the JDK you're using, it simply means the level in which your java code will be interpreted as if it were no higher than the language level version, using any particular version of the JDK that is at least at or higher than the given language level setting.

IE: you're using JDK 1.8+, setting your language level to 5.0 means you will only be able to use java features that are up to JDK 1.5.

Upvotes: 21

Chris Martin
Chris Martin

Reputation: 30756

Sounds like you have the wrong language level set in Eclipse.

See @Override gives error in eclipse? :

to change the language level go To Project > Properties > Java Compiler and set the language level there. You may need to click to enable project specific settings.

Upvotes: 1

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