Java中方法返回多个值？---- 泛型的应用

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在开发的时候，总能碰到一个方法返回多个值的情形，除了将对象以入参的方式传到方法内部以外，还可以通过泛型构造元组来实现。

元组类实例

public class Tuple {public static void main(String[] args) {System.out.println(Tuple.create("asdf", 123));}public static <A, B> TwoTuple<A, B> create(A a, B b) {return new TwoTuple<A, B>(a, b);}public static <A, B, C> ThreeTuple<A, B, C> create(A a, B b, C c) {return new ThreeTuple<A, B, C>(a, b, c);}public static <A, B, C, D> FourTuple<A, B, C, D> create(A a, B b, C c, D d) {return new FourTuple<A, B, C, D>(a, b, c, d);}private static class TwoTuple<A, B> extends Tuple{public final A a;public final B b;public TwoTuple(A a, B b) {this.a = a;this.b = b;}@Overridepublic String toString() {StringBuilder builder = new StringBuilder();builder.append("TwoTuple [");if (a != null)builder.append("a=").append(a).append(", ");if (b != null)builder.append("b=").append(b);builder.append("]");return builder.toString();}}private static class ThreeTuple<A, B, C> extends TwoTuple<A, B> {public final C c;public ThreeTuple(A a, B b, C c) {super(a, b);this.c = c;}@Overridepublic String toString() {StringBuilder builder = new StringBuilder();builder.append("ThreeTuple [");if (a != null)builder.append("a=").append(a).append(", ");if (b != null)builder.append("b=").append(b);if (c != null)builder.append("c=").append(c).append(", ");builder.append("]");return builder.toString();}}private static class FourTuple<A, B, C, D> extends ThreeTuple<A, B, C> {public final D d;public FourTuple(A a, B b, C c, D d) {super(a, b, c);this.d = d;}@Overridepublic String toString() {StringBuilder builder = new StringBuilder();builder.append("FourTuple [");if (a != null)builder.append("a=").append(a).append(", ");if (b != null)builder.append("b=").append(b);if (c != null)builder.append("c=").append(c).append(", ");if (d != null)builder.append("d=").append(d).append(", ");builder.append("]");return builder.toString();}}}

使用方法

public class Test {public static void main(String[] args) {Tuple t = Tuple.create("123", 1);System.out.println(Tuple.create("asdf", 123));}}

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