How to Use Static Blocks in Java
In the Java programming language, a block is a group of lines of code enclosed in curly braces. Blocks serve many purposes in Java--for instance, control Java keywords such as "while" take a block as an argument. In particular, Java supports "static blocks." A static block gets executed exactly once per class--rather than once per object created in the class, as would be the case for code included in a constructor method. You can use static Java blocks to perform one-time tasks when the class in question gets loaded into memory by the Java Virtual Machine.
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Instructions
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1
Define the class where you want the static block to be, as in the following sample code:
public class PairOfInts {
static int x,y;
static String status = "Global initialization not yet done";
public PairOfInts(int a,b) {
x=a;
y=b;
}
}
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2
Add the delimiters for the static block inside the class definition, as in the following sample code:
public class PairOfInts {
static int x,y;
static String status = "Global initialization not yet done";
static {
}
public PairOfInts(int a,b) {
x=a;
y=b;
}
}
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3
Add the one-time initialization code between the static block delimiters, as in the following sample code:
public class PairOfInts {
static int x,y;
static String status = "Global initialization not yet done";
static {
// Will execute at most once per execution of the Java application
status = "Global initialization done";
}
public PairOfInts(int a,b) {
x=a;
y=b;
}
}
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