Generics mean parameterized types. The idea is to allow type (Integer, String, … etc, and user-defined types) to be a parameter to methods, classes, and interfaces. Using Generics, it is possible to create classes that work with different data types. For example: // A Simple Java program to show working of user defined // Generic …
How to fix “Caused by: java.lang.NoClassDefFoundErr”
Use code below to compile and run our program: javac -d . Caller.java java com.Caller
How to install JavaFX on Mac
The simplest way I have seen is to use brew: brew tap bell-sw/liberica brew install –cask liberica-jdk15-full Then we could use terminal at least to run our JavaFX program. However, I think here would be more setting steps if you wanna run it in some IDE.
Java Development Configuration in VS Code MacOS
Got jdk path /usr/libexec/java_home -V Set JAVA.HOME VSCode -> Code -> Preference -> setting -> enter java.home -> setting.json
Intent In Android Studio
Build an intent An Intent is an object that provides runtime binding between separate components, such as two activities. The Intent represents an app’s intent to do something. You can use intents for a wide variety of tasks, but in this lesson, your intent starts another activity. In MainActivity, add the EXTRA_MESSAGE constant and the …
Why do we should use intValue() to compare?
The Integer.intValue() is used to get the primitive int value of Integer. The other test cases pass for you because the int values are low and the auto-unboxing feature of java does the value comparison for you. But for this one test case the int values are pretty large and hence it leads to object …
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HashMap computeIfAbsent() method in Java with Examples
The computeIfAbsent(Key, Function) method of HashMap class is used to compute value for a given key using the given mapping function, if key is not already associated with a value (or is mapped to null) and enter that computed value in Hashmap else null. If mapping function of this method returns null, then no mapping …
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Why use Deque over Stack in Java
From JavaDoc for Stack, we could see: "A more complete and consistent set of LIFO stack operations is provided by the Deque interface and its implementations, which should be used in preference to this class. For example:" Deque<Integer> stack = new ArrayDeque<>(); Here are some answers from Why should I use Deque over Stack?. Inconsistency: …
How to get random number in a range in Java
Let’s use the Math.random method to generate a random number in a given range: public int getRandomNumber(int min, int max) { return (int) ((Math.random() * (max – min)) + min); } Why does that work? Well, let’s look at what happens when Math.random returns 0.0, it’s the lowest possible output: 0.0 * (max – min) …
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How to sort 2D array in Java
My code : Arrays.sort(intervals, new Comparator<int[]>(){ @Override public int compare( int[] a, int[] b ){ return a[0]==b[0] ? a[1] – b[1] : a[0] – b[0]; // return Integer.compare( a[0], b[0] ); } }); And here is an simple way: Arrays.sort(myArr, (a, b) -> a[0] – b[0]);