How to send a Map in JSON
Key always should be string. Why it still doesn’t work? Because the error is caused by the redundant brace inside of “elementsToUpdate”. Below is an example:
java
Service will not start: error 1067: the process terminated unexpectedly
Goto: Registry-> HKEY_LOCAL_MACHINE-> System-> CurrentControlSet-> Services. Find the concerned service & delete it. Close regedit. Reboot the PC & Re-install the concerned service. Now the error should be gone.
java.lang.NoClassDefFoundError: Could not initialize class org.codehaus.groovy.vmplugin.v7.Java7
How do you run the application? It’s probably because you use Gradle as the build system and JDK14 and the Gradle version is old. Reference: https://github.com/gradle/gradle/issues/10248 If you use Gradle Wrapper then refer to $PROJECT_ROOT/gradle/wrapper/gradle-wrapper.properties. Property distributionUrl should be: distributionUrl=https\://services.gradle.org/distributions/gradle-6.3-bin.zip If it’s an older version then change it, run ./gradlew clean build and try again.
Understanding the difference between null and ‘\u000’ in Java
The language specification is where null is defined, and it says There is also a special null type, the type of the expression null, which has no name. Because the null type has no name, it is impossible to declare a variable of the null type or to cast to the null type. The null … Read more
Java – removing first character of a string
Use the substring() function with an argument of 1 to get the substring from position 1 (after the first character) to the end of the string (leaving the second argument out defaults to the full length of the string).
How to check type of variable in Java?
Java is a statically typed language, so the compiler does most of this checking for you. Once you declare a variable to be a certain type, the compiler will ensure that it is only ever assigned values of that type (or values that are sub-types of that type). The examples you gave (int, array, double) these … Read more
Session TimeOut in web.xml
To set a session-timeout that never expires is not desirable because you would be reliable on the user to push the logout-button every time he’s finished to prevent your server of too much load (depending on the amount of users and the hardware). Additionaly there are some security issues you might run into you would … Read more
Java integer-double division confusion
In your first example: sum is an int, and 4 is also an int. Java is dividing one integer by another and getting an integer result. This all happens before it assigns the value to double avg, and by then you’ve already lost all information to the right of the decimal point. Try some casting. OR
What does ‘0’ do in Java?
Ascii characters are actually numbers. And 0 .. 9 digits are numbers starting from decimal 48 (0x30 hexadecimal). So to get the value of any character digit, you can just remove the ‘0’, ie 48. If you don’t remove ‘0’ (48) the total sum will be over by 48 * numberOfDigits. See an ascii table to locate digits in it. … Read more
How to convert int[] into List in Java?
There is no shortcut for converting from int[] to List<Integer> as Arrays.asList does not deal with boxing and will just create a List<int[]> which is not what you want. You have to make a utility method.