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public class TestCallback { public static void main(String[] args) throws Exception { TestCallback main = new TestCallback(); main.test(new ICallBack() { public void callbackMethod() { System.out.println(">> ICallBack.callbackMethod()"); } }); } public void test(ICallBack callback) { callback.callbackMethod(); }} interface ICallBack { public void callbackMethod();}

private void findDuplicateValue(String[] list) { for (int i = 0; i " + i + ". " + str1); break; } } } }

private String generate() { int len = 6; int rnum = (int) Math.floor(Math.random() * Math.pow(10, len)); StringBuffer sb = new StringBuffer(String.valueOf(rnum)); while (sb.toString().length() < len) { sb.append("0"); } return System.currentTimeMillis() + "_" + sb.toString();}

String str1 = "ABC";String str2 = new String("ABC");String str3 = "ABC"; System.out.println("str1 : " + str1);System.out.println("str2 : " + str2);System.out.println("str3 : " + str3);System.out.println(); System.out.println("str1.toString() : " + str1.toString());System.out.println("str2.toString() : " + str2.toString());System.out.println("str3.toString() : " + str3.toString());System.out.prin..

Object obj = new Object();System.out.println("1. " + obj.toString()); System.out.print("2. ");System.out.print(obj.getClass().getName());System.out.print("@");System.out.print(Long.toHexString(System.identityHashCode(obj)));System.out.println(); // console1. java.lang.Object@1c78e572. java.lang.Object@1c78e57

Long num = 29855319L;System.out.println("10진수: " + num);System.out.println(" 2진수: " + Long.toBinaryString(num));System.out.println(" 8진수: " + Long.toOctalString(num));System.out.println("16진수: " + Long.toHexString(num)); // console10진수: 29855319 2진수: 1110001111000111001010111 8진수: 16170712716진수: 1c78e57