guava 前置条件 Preconditions

/**
 * Created by lgq on 16-1-5.
 */
public class TestPreconditions {

    /**
     * 前置条件检查，当条件不满足时，就会抛出异常
     */
    @Test
    public void testPreconditions(){
        String constantName = null;
        //Preconditions.checkNotNull(constantName,"constantName 为 null");

        String str = "abc";
        Preconditions.checkNotNull(str,"str 为 null"); // 不会输出

        int age = 23;
        Integer number = 12;
        //Preconditions.checkArgument(age < 20, "age 必须要< 20");
        Preconditions.checkArgument(number < 20, "number 必须要< 20");


        List<Integer> integerList = Lists.newArrayList(3,5,6,98,2,45);
        for(int i=0; i<integerList.size(); i++) {
            // 检查数组下标是否越界
            int passIndex = Preconditions.checkElementIndex(i, integerList.size());
            //System.out.println("下标："+ passIndex + " ==> 满足要求");
        }

        // 检查下标值7 是否在集合integerList中
        //Preconditions.checkElementIndex(7, integerList.size());

        //Preconditions.checkPositionIndex(8, integerList.size());

        Preconditions.checkPositionIndexes(2, 4, integerList.size());

        // 判断是否为true，当为false时，会抛出IllegalStateException
        Preconditions.checkState(4 < 3);

    }

}