| 4. 6. 2. For statement in detail |
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It is common to declare a variable and assign a value to it in the initialization part.
The variable declared will be visible to the expression and update parts as well as to
the statement block. |
For example, the following for statement loops five times and each time prints the value of i.
Note that the variable i is not visible anywhere else since it is declared within the for loop. |
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public class MainClass {
public static void main(String[] args) {
for (int i = 0; i < 5; i++) {
System.out.println(i + " ");
}
}
}
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The initialization part of the for statement is optional. |
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public class MainClass {
public static void main(String[] args) {
int j = 0;
for (; j < 3; j++) {
System.out.println(j);
}
// j is visible here
}
}
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The update statement is optional. |
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public class MainClass {
public static void main(String[] args) {
int k = 0;
for (; k < 3;) {
System.out.println(k);
k++;
}
}
}
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You can even omit the booleanExpression part. |
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public class MainClass {
public static void main(String[] args) {
int m = 0;
for (;;) {
System.out.println(m);
m++;
if (m > 4) {
break;
}
}
}
}
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If you compare for and while, you'll see that you can always replace the while statement
with for. This is to say that |
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while (expression) {
...
}
can always be written as
for ( ; expression; ) {
...
}
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