String[] directions = {"UP","DOWN","RIGHT","LEFT"};
String input = "DOWN 123 test";
有没有一种方法可以检查输入字符串是否以方向中的一个值开头,而不使用分割输入值的方式?
private static final String[] DIRECTIONS = {"UP","DOWN","RIGHT","LEFT"};
public static String getDirectionPrefix(String input) {
for (String direction : DIRECTIONS) {
if (input.startsWith(direction)) {
return direction;
}
}
return null;
}
或者使用Java 8的流:
private static final List<String> DIRECTIONS = Arrays.asList("UP","DOWN","RIGHT","LEFT");
public static Optional<String> getDirectionPrefix(String input) {
return DIRECTIONS.stream().filter(d -> input.startsWith(d)).findFirst();
}
String startsWith
函数。public static void main(String[] args) {
String[] directions = { "UP", "DOWN", "RIGHT", "LEFT" };
String input = "DOWN 123 test";
for (String s : directions) {
if (input.startsWith(s)) {
System.out.println("Yes - "+s);
break;
} else {
System.out.println("no - "+s);
}
}
}
输出
no - UP
Yes - DOWN
String.startsWith()
方法。for(String direction : directions) {
if(input.startsWith(direction) {
// Do something
}
}
String[] directions = {"UP","DOWN","RIGHT","LEFT"};
String input = "DOWN 123 test";
for(String dir:directions){
if(input.startsWith(dir)){
System.out.println("input string starts with:"+dir);
}
}