What is scope and block in Java?

What is scope and block in Java?

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Block scope in java with example

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Here is the requested information in Simplified Chinese:

public class Test {
public static void main(String[] args) {
{
int y = 20;
System.out.println(x); // 10
System.out.println(y); // 20
}
System.out.println(x); // 10
}
}

public class Test {
public void printX() {
System.out.println(x);
}
}

public class Test {
public void printX() {
System.out.println(x);
}
}

public class Test {
public void printX() {
System.out.println(x);
}
}