| 知乎专栏 |
目录
Supplier<String> supplier = () -> "hello, world";
String result = supplier.get();
System.out.println(result);
Supplier stringSupplier = () -> new String("Hi Neo");
String string = stringSupplier.get();
System.out.println(string);
Supplier<LocalDateTime> currentTime = () -> LocalDateTime.now();
LocalDateTime now = currentTime.get(); // 计算当前时间
Optional<String> optional = Optional.ofNullable("hello");
String orElseGet = optional.orElseGet(() -> "world");
Supplier userSupplier= () -> new User(1,"netkiller");
User user=userSupplier.get();
System.out.println(user.getName());
package cn.netkiller.test;
import java.util.function.Supplier;
public class TestSupplier {
private final int age = 24;
TestSupplier() {
System.out.println(age);
}
public static void main(String[] args) {
Supplier<TestSupplier> supplier = TestSupplier::new;
//调用get()方法，此时会调用对象的构造方法，即获得到真正对象
supplier.get();
System.out.println(supplier.get().test());
TestSupplier test = supplier.get();
System.out.println(test.test());
}
private String test() {
return "Helloworld!!!";
}
}
package cn.netkiller.test;
import java.util.function.Supplier;
public class TestSupplier {
private final int age = 24;
private final String name;
TestSupplier(String name) {
this.name = name;
// System.out.println(name);
}
public static void main(String[] args) {
Supplier<String> stringSupplier = () -> {
return "test1";
};
System.out.println(stringSupplier.get());
Supplier<String> stringSupplier1 = () -> "test2";
System.out.println(stringSupplier1.get());
Supplier<TestSupplier> testSupplier = () -> new TestSupplier("Neo");
System.out.println(testSupplier.get().name);
// String name = "Netkiller";
// Supplier<TestSupplier> testSupplier1 = (name) -> {new TestSupplier(name)};
// System.out.println(testSupplier1.get().name);
// System.out.println(test.test());
}
private String test() {
return "Helloworld!!!";
}
}
package cn.netkiller.test;
import java.util.concurrent.ExecutionException;
import java.util.function.Supplier;
public class Test {
public static void main(String[] args) throws ExecutionException, InterruptedException {
System.out.println(Thread.currentThread());
process(() -> {
System.out.println(Thread.currentThread().getName() + " Process...");
return "Test";
});
Supplier<String> stringSupplier1 = () -> "netkiller";
process(stringSupplier1);
}
public static <T> void process(Supplier<T> supplier) {
// System.out.println(Thread.currentThread().getName() + " Process...");
// CompletableFuture<T> runAsync = CompletableFuture.supplyAsync(supplier);
// runAsync.join();
// System.out.println(variable.get());
T value = supplier.get();
System.out.println(value);
}
}
IntSupplier - 有getAsInt()方法
package cn.netkiller.test;
import java.util.function.IntSupplier;
import java.util.stream.IntStream;
public class Test {
public static void main(String[] args) {
IntSupplier naturalGenerator = new IntSupplier() {
int currentValue = 0;
public int getAsInt() {
return currentValue++;
}
};
IntStream.range(0, 10).forEach((n) -> {
System.out.println(naturalGenerator.getAsInt());
});
}
}
自定义 getAsInt 抽象方法，可以定制步进值
package cn.netkiller.test;
import java.util.function.IntSupplier;
import java.util.stream.IntStream;
public class Test {
public static void main(String[] args) {
System.out.println(Thread.currentThread());
IntSupplier naturalGenerator = new IntSupplier() {
int currentValue = 1;
public int getAsInt() {
return currentValue *= 2;
}
};
IntStream.range(0, 10).forEach((n) -> {
System.out.println(naturalGenerator.getAsInt());
});
}
}
LongSupplier - 有getAsLong()方法
LongSupplier longSupplier1 = () -> LocalDate.now().toEpochDay();
System.out.println(longSupplier1.getAsLong());
LongSupplier longSupplier2 = () -> Long.parseLong("1024");
System.out.println(longSupplier2.getAsLong());
LongSupplier longSupplier3 = () -> {
long num1 = 30L;
long num2 = 50L;
return num1 * num2;
};
System.out.println(longSupplier3.getAsLong());
LongSupplier time = new Date()::getTime;
System.out.println(time.getAsLong());
public static void main(String[] args) {
String id = test(() -> new Random().nextLong());
System.out.println(id);
}
public static String test(LongSupplier ls) {
return "no. " + ls.getAsLong();
}
DoubleSupplier - 有getAsDouble()方法
DoubleSupplier random = () -> new Random().nextDouble();
System.out.println(random.getAsDouble());
DoubleSupplier doubleSupplier = () -> Double.parseDouble("123.0987");
System.out.println(doubleSupplier.getAsDouble());
DoubleSupplier doubleSupplier1 = () -> {
double val1 = 35.30;
double val2 = 45.97;
return val1 * val2;
};
System.out.println(doubleSupplier1.getAsDouble());
DoubleSupplier random1 = new Random()::nextDouble;
System.out.println(random1.getAsDouble());
BooleanSupplier - 有getAsBoolean()方法。
BooleanSupplier booleanSupplier1 = () -> LocalDate.now().isLeapYear();
System.out.println(booleanSupplier1.getAsBoolean());
BooleanSupplier booleanSupplier2 = () -> "netkiller".length() > 5;
System.out.println(booleanSupplier2.getAsBoolean());
BooleanSupplier booleanSupplier3 = () -> {
int num = 16;
if (num % 2 == 0) {
return true;
}
return false;
};
System.out.println(booleanSupplier3.getAsBoolean());