留下两个例子作为参考,
1. 追逐小方块的例子
2. HashMap 和 Iterator 的例子
Example one:
import acm.graphics.*;
import acm.program.*;
import java.awt.*;
import java.awt.event.*; public class TargetSeeker extends GraphicsProgram { /* private constants */
private static final int TARGET_SIZE = 10;
private static final int SEEKER_SIZE = 20;
private static final int PAUSE_TIME = 10; public void run() {
initTarget();
initSeeker();
addMouseListeners(); while (true) {
seek();
}
} private void initTarget() {
targetSquare = new GRect(TARGET_SIZE, TARGET_SIZE);
targetSquare.setColor(Color.red);
targetSquare.setFilled(true);
targetX = getWidth() / 2;
targetY = getHeight() / 2;
add(targetSquare, targetX - TARGET_SIZE/2, targetY - TARGET_SIZE/2);
} private void initSeeker() {
seeker = new GRect(SEEKER_SIZE, SEEKER_SIZE);
add(seeker, 0, 0);
} private int moveAmount(double seekerPos, double targetPos) {
int amount = 0;
if (targetPos > seekerPos) {
amount = 1;
} else if (targetPos < seekerPos) {
amount = -1;
}
return amount;
} private void seek() {
pause(PAUSE_TIME);
double seekerMidX = seeker.getX() + SEEKER_SIZE / 2;
int dx = moveAmount(seekerMidX, targetX);
double seekerMidY = seeker.getY() + SEEKER_SIZE / 2;
int dy = moveAmount(seekerMidY, targetY); seeker.move(dx, dy);
} public void mouseClicked(MouseEvent e) {
targetX = e.getX();
targetY = e.getY();
remove(targetSquare);
add(targetSquare, targetX - TARGET_SIZE/2, targetY - TARGET_SIZE/2);
} /* private instance variable */
private int targetX;
private int targetY;
private GRect targetSquare;
private GRect seeker;
}
Example two:
public void PrintMatchingKeys(HashMap<String, String> map) {
ArrayList<String> keys = new ArrayList<String>();
Iterator<String> it = map.keySet().iterator();
while (it.hasNext()) {
// keys is array list, it is the key (String type) of map
keys.add(it.next());
}
// Reset "it" iterator to allow us to iterate over keys again
it = map.keySet().iterator();
while (it.hasNext()) {
String key = it.next();
String value = map.get(key);
// of course contain
if (key.contains(value)) {
println(key + ": " + value);
}
}
}