각각의 블럭을 의도가 들어나도록 메서드 추출함..

GuavaTest1.java

package com.springapp.mvc;
import static com.google.common.base.Preconditions.*;
import static java.lang.System.err;
public class GuavaTest1 {

    private final boolean initialzed = false;

    public void testForNonNullArgument(final String parameter)
    {
        final String localPrameter = checkNotNull(parameter, "null값은"
                + "허용되지 않습니다.");
    }

    public void testDivisorNotZero(final int divisor){
        checkArgument(divisor != 0, "0으로 나눌 수 없습니다.");
    }

    public void testArrayElement(final String[] strArray,
                                 final int indexNumber){
        final int index = checkElementIndex(indexNumber, strArray.length,
                "지정된 Array 요소 위치가 벗어났습니다.");
    }

    public void testarrayPosition(final String[] strarray, final int indexNumber){
        final int index = checkPositionIndex(indexNumber, strarray.length,
                "지정된 Array 요소 위치가 벗어났습니다.");
    }

    public void testState(){
        checkState(this.initialzed, "초기화 되지 않았습니다.");
    }

    public static void printHeader(final String newHeaderText){
        err.println("\n=====================");
        err.println("===" + newHeaderText);
        err.println("=======================");
    }


    public static void main(String[] args) {
        final GuavaTest1 test1 = new GuavaTest1();

        test1(test1, "preconditions.checkNotNull");
        test2(test1, "precondition.checkArgument");
        test3(test1, "Preconditions.checkElementIndex");
        test4(test1, "Preconditions.checkPositionIndex");
        test5(test1, "Preconditions.checkState");
    }

    private static void test5(GuavaTest1 test1, String message) {
        printHeader(message);
        try{
            test1.testState();
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    private static void test4(GuavaTest1 test1, String message) {
        printHeader(message);
        try{
            test1.testarrayPosition(new String[]{"Dustin","java"},3);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    private static void test3(GuavaTest1 test1, String message) {
        printHeader(message);
        try{
            test1.testArrayElement(new String[]{"Dustin","java"},3 );
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    private static void test2(GuavaTest1 test1, String message) {
        printHeader(message);
        try{
            test1.testDivisorNotZero(0);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    private static void test1(GuavaTest1 test1, String message) {
        printHeader(message);
        try{
            test1.testForNonNullArgument(null);
        }catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}