最新IT技術情報_arkgame.com

サンプルコード
package com.changfa.study;
import org.bson.Document;

import com.mongodb.MongoClient;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;

public class MongoTest1 {
public static void main(String[] args) {
MongoClient client = new MongoClient(“172.17.2.100”, 27017);
MongoDatabase db = client.getDatabase(“employeeDB”);

MongoCollection<Document> mc = db.getCollection(“empinfo”);

long count = mc.count();

System.out.println(count);

for (Document dmt : mc.find()) {
System.out.println(dmt);
}

}
}

サンプルコード:
package study;
import java.util.ArrayList;
import java.util.Collections;

public class CollectionDemo {

public static void main(String[] args) {
// Create a list of strings
ArrayList<String> cft = new ArrayList<String>();
cft.add(“Geeks”);
cft.add(“Dear”);
cft.add(“Company”);
cft.add(“Reuser”);
cft.add(“Employee info”);

/*
* Collections.sort method is sorting the
* elements of ArrayList in ascending order.
*/
Collections.sort(cft);

// Let us print the sorted list
System.out.println(“List after the use of” + ” Collection.sort() :\n” + cft);

}
結果
List after the use of Collection.sort() :
[Company, Dear, Employee info, Geeks, Reuser]

Javaコード
package study;

import java.util.Objects;

public class ObjectEqualsDemo {

public static void main(String[] args) {
String strAA = null;
String strBB = “this is sample”;
String strCC = null;
String strDD = “this is sample”;

System.out.println(Objects.equals(strAA, strBB));
System.out.println(Objects.equals(strAA, strCC));
System.out.println(Objects.equals(strBB, strDD));

}

}

結果
false
true
true

1.Javaコード
public enum UserCode{
EMPA(“AAA”, 101),
EMPB(“BBB”, 202),
EMPC(“CCC”, 303),
;

private final String addr;
private final int id;

private UserCode(final String addr, final int id) {
this.addr = addr;
this.id = id;
}

public String getString() {
return this.addr;
}

public int getInt() {
return this.id;
}
}

2.利用方法
String addr = UserCode.EMPA.getString();
int id = UserCode.EMPA.getInt();

Log.debug(“enumテスト”, addr); // AAA が出力される
Log.debug(“enumテスト”, “” + id); // 101 が出力される

1.TimeStampUtil.java
クラスの定義
package study;

import java.sql.Timestamp;
import java.text.SimpleDateFormat;

public class TimeStampUtil {
public static String formatTimeStamp(Timestamp timestamp, String timeFormat) {
return new SimpleDateFormat(timeFormat).format(timestamp);
}

public static Timestamp current() {
return new Timestamp(System.currentTimeMillis());
}

}

2.mainクラス
package study;
public class TimeStampDemo {

public static final String TIME_VALUE_FORMAT = “yyyy/MM/dd HH:mm:ss”;

public static void main(String[] args) {
String aa = TimeStampUtil.formatTimeStamp(TimeStampUtil.current(), TIME_VALUE_FORMAT);
System.out.println(“現在時間:\n” + aa);

}

}

現在時間:
2018/07/17 12:02:52

package study;

import java.util.ArrayList;

public class ArrayListTestCase {

public static void main(String[] args) {
ArrayList<Integer> tt = new ArrayList<Integer>();
tt.add(101);
tt.add(102);
tt.add(103);
tt.add(104);

// ArrayListのコピー
@SuppressWarnings(“unchecked”)
ArrayList<Integer> ff = (ArrayList<Integer>) tt.clone();
System.out.println(“実行結果:”);
for (Integer a : ff) {
System.out.println(a);
}
}

}

結果:
101
102
103
104

サンプルコード
public static int convertToInt(String number, int defaultValue) {
if (TextUtils.isEmpty(number)) {
return defaultValue;
}
try {
return Integer.parseInt(number);
} catch (Exception e) {
return defaultValue;
}
}
}