java 8 四大内置函数接口使用示例

public interface Consumer<T> {
    void accept(T t);
}

public void happy(double money, Consumer<Double> consumer) {
     consumer.accept(money);
}

happy(1000, money -> System.out.println("吃喝玩乐"));

happy(10000, money -> System.out.println("旅游"));

public interface Supplier<T> {
    T get();
}

public List<Integer> getNumList(int num, Supplier<Integer> supplier) {
    List<Integer> list = new ArrayList<>();
  
 for(int i = 0; i < num; i++) {
        Integer n = supplier.get();
      list.add(n);
 }
    
 return list;
}

getNumList(10, () -> (int)(Math.random() * 100))

public interface Function<T, R> {
    R apply(T t);
}

public String strHandler(String str, Function<String, String> function) {
        return function.apply(str);
}

strHandler("   Lambda  ", str -> str.trim().toUpperCase())

public interface Predicate<T> {
    boolean test(T t);
}

public List<String> filterStr(List<String> list, Predicate<String> predicate) {
    List<String> strList = new ArrayList<>();
    
 for(String str : list) {
     if(predicate.test(str)) {
            strList.add(str);
        }
    }
    
 return strList;
}

List<String> strings = Arrays.asList("Hello", "Lambda", "Function", "Java");
filterStr(strings, str -> str.length() > 5);