package com.case;import java.util.List;import com.google.common.base.Function;
import com.google.common.collect.Lists;/*** Step on the pit with guava* * @author James* @version $Id: GuavaListsTransFormCase.java, v 0.1 2017年3月24日 下午8:36:36 James Exp $*/
public class GuavaListsTransFormCase {public static void main(String[] args) {List<A> as = Lists.newArrayList();A a = new A();a.setC(1);as.add(a);try {System.out.println("case1 start");transFormCase1(as);} catch (Exception e) {System.out.println(e.getMessage());} finally {System.out.println("case1 end");}try {System.out.println("case2 start");transFormCase2(as);} catch (Exception e) {System.out.println(e.getMessage());} finally {System.out.println("case2 end");}}private static List<B> transFormCase1(List<A> as) {return Lists.transform(as, new Function<A, B>() {@Overridepublic B apply(A input) {B b = new B();b.setC(input.getC() / 0);//...variablesreturn b;}});}private static List<B> transFormCase2(List<A> as) {return Lists.newArrayList(Lists.transform(as, new Function<A, B>() {@Overridepublic B apply(A input) {B b = new B();b.setC(input.getC() / 0);//...variablesreturn b;}}));}
}class A {private int c;//...variablespublic int getC() {return c;}public void setC(int c) {this.c = c;}}class B {private int c;//...variablespublic int getC() {return c;}public void setC(int c) {this.c = c;}
}

执行结果：

case1 start
case1 end
case2 start
/ by zero
case2 end

case2比case1多了一步,在使用Lists.transform的时候将转换结果，用Lists.newArrayList 重新产生一个新的list。以确保function内的代码（比如调用远程方法，操作数据库等容易抛出异常的代码）立即被执行，而不是在要使用的时候执行，从而导致异常没有在预期的地方被捕获。