invalid target release: 1.7
You need to set JAVA_HOME to your jdk7 home directory, for example on Microsoft Windows: “C:\Program Files\Java\jdk1.7.0_40” or on OS X: /Library/Java/JavaVirtualMachines/jdk1.7.0_40.jdk/Contents/Home
java-7
What is the difference between PermGen and Metaspace?
The main difference from a user perspective – which I think the previous answer does not stress enough – is that Metaspace by default auto increases its size (up to what the underlying OS provides), while PermGen always has a fixed maximum size. You can set a fixed maximum for Metaspace with JVM parameters, but … Read more
Why does the difference between 30 March and 1 March 2020 erroneously give 28 days instead of 29?
The problem is that because of Daylight Saving Time shift (on Sunday, March 8, 2020), there are 28 days and 23 hours between those dates. TimeUnit.DAYS.convert(…) truncates the result to 28 days. To see the problem (I’m in US Eastern time zone): SimpleDateFormat fmt = new SimpleDateFormat(“dd-MM-yyyy HH:mm:ss”); long diff = fmt.parse(“30-03-2020 00:00:00”).getTime() – fmt.parse(“1-03-2020 … Read more
Java: int array initializes with nonzero elements
Here we are faced with a bug in the JIT-compiler. Compiler determines that the allocated array is filled after allocation in Arrays.fill(…), but the check for uses between the allocation and the fill is faulty. So, compiler performs an illegal optimization – it skips zeroing of allocated array. This bug is placed in Oracle bug … Read more
How to set IntelliJ IDEA Project SDK
For a new project select the home directory of the jdk eg C:\Java\jdk1.7.0_99 or C:\Program Files\Java\jdk1.7.0_99 For an existing project. 1) You need to have a jdk installed on the system. for instance in C:\Java\jdk1.7.0_99 2) go to project structure under File menu ctrl+alt+shift+S 3) SDKs is located under Platform Settings. Select it. 4) click … Read more
How should I use try-with-resources with JDBC?
I realize this was long ago answered but want to suggest an additional approach that avoids the nested try-with-resources double block. public List<User> getUser(int userId) { try (Connection con = DriverManager.getConnection(myConnectionURL); PreparedStatement ps = createPreparedStatement(con, userId); ResultSet rs = ps.executeQuery()) { // process the resultset here, all resources will be cleaned up } catch (SQLException … Read more
Can Java 8 code be compiled to run on Java 7 JVM?
No, using 1.8 features in your source code requires you to target a 1.8 VM. I just tried the new Java 8 release and tried compiling with -target 1.7 -source 1.8, and the compiler refuses: $ javac Test -source 1.8 -target 1.7 javac: source release 1.8 requires target release 1.8
How to set -source 1.7 in Android Studio and Gradle
Java 7 support was added at build tools 19. You can now use features like the diamond operator, multi-catch, try-with-resources, strings in switches, etc. Add the following to your build.gradle. android { compileSdkVersion 19 buildToolsVersion “19.0.0” defaultConfig { minSdkVersion 7 targetSdkVersion 19 } compileOptions { sourceCompatibility JavaVersion.VERSION_1_7 targetCompatibility JavaVersion.VERSION_1_7 } } Gradle 1.7+, Android gradle … Read more
java.nio.file.Path for a classpath resource
This one works for me: return Path.of(ClassLoader.getSystemResource(resourceName).toURI());
Java 7 language features with Android
If you are using Android Studio, the Java 7 language should be enabled automatically without any patches. Try-with-resource requires API Level 19+, and NIO 2.0 stuff are missing. If you can’t use Java 7 features, see @Nuno’s answer on how to edit your build.gradle. The following is for historical interest only. A small part of … Read more