gistfile1.java

@Test
	public void testString()
		String texto = "";
		System.out.println("--------------------Operador + -----------------------------");
		Date date = new Date(System.currentTimeMillis());
		DateFormat formatter = new SimpleDateFormat("HH:mm:ss:SSS");
		String initOperador = formatter.format(date);
		System.out.println(initOperador);
		for(int i = 0; i < 100000; i++){
			texto += i + "text";
		}
		date = new Date(System.currentTimeMillis());
		String fimOperador = formatter.format(date);
		System.out.println(fimOperador);
		BigDecimal a = new BigDecimal(initOperador.replaceAll(":", ""));
		BigDecimal b = new BigDecimal(fimOperador.replaceAll(":", ""));
		System.out.println("tempo : " + b.subtract(a) );
		
		System.out.println("-------------------String Format----------------------------");
                texto = "";
		date = new Date(System.currentTimeMillis());
		String initFormat = formatter.format(date);
		System.out.println(initFormat);
		for(int i = 0; i < 100000; i++){
			texto = String.format("%s%dtext", texto, i);
		}
		date = new Date(System.currentTimeMillis());
		String fimFormat = formatter.format(date);
		System.out.println(fimFormat);
		BigDecimal c = new BigDecimal(initFormat.replaceAll(":", ""));
		BigDecimal d = new BigDecimal(fimFormat.replaceAll(":", ""));
		System.out.println(String.format("tempo : %s", d.subtract(c)) );
		
		System.out.println("-------------------String concat----------------------------");
		texto = "";
		date = new Date(System.currentTimeMillis());
		String initConcat = formatter.format(date);
		System.out.println(initConcat);
		for(int i = 0; i < 100000; i++){
			texto = texto.concat(String.valueOf(i)).concat("text"); 
		}
		date = new Date(System.currentTimeMillis());
		String fimConcat = formatter.format(date);
		System.out.println(fimConcat);
		BigDecimal e = new BigDecimal(initConcat.replaceAll(":", ""));
		BigDecimal f = new BigDecimal(fimConcat.replaceAll(":", ""));
		System.out.println(new String("tempo : ").concat(f.subtract(e).toPlainString()));
		
			
		System.out.println("-------------------String Builder---------------------------");
		StringBuilder textoS = new StringBuilder();
		date = new Date(System.currentTimeMillis());
		String initStringBuilder = formatter.format(date);
		System.out.println(initStringBuilder);
		for(int i = 0; i < 100000; i++){
			textoS.append(String.valueOf(i)).append("text");
		}
		date = new Date(System.currentTimeMillis());
		String fimStringBuilder = formatter.format(date);
		System.out.println(fimStringBuilder);
		BigDecimal g = new BigDecimal(initStringBuilder.replaceAll(":", ""));
		BigDecimal h = new BigDecimal(fimStringBuilder.replaceAll(":", ""));
		System.out.println(new StringBuilder("tempo : ").append(h.subtract(g)));
		
		System.out.println("-------------------String Buffer---------------------------");
		StringBuffer textoSB = new StringBuffer();
		date = new Date(System.currentTimeMillis());
		String initStringBuffer = formatter.format(date);
		System.out.println(initStringBuffer);
		for(int i = 0; i < 100000; i++){
			textoSB.append(String.valueOf(i)).append("text");
		}
		date = new Date(System.currentTimeMillis());
		String fimStringBuffer = formatter.format(date);
		System.out.println(fimStringBuffer);
		BigDecimal i = new BigDecimal(initStringBuffer.replaceAll(":", ""));
		BigDecimal j = new BigDecimal(fimStringBuffer.replaceAll(":", ""));
		System.out.println(new StringBuffer("tempo: ").append(j.subtract(i)) );
    }

Saida

//10x menos itens no loop
--------------------Operador + -----------------------------
17:13:27:330
17:14:07:718
tempo : 80388
-------------------String Format----------------------------
17:14:07:723
17:15:55:196
tempo : 147473
-------------------String concat----------------------------
17:15:55:198
17:16:46:805
tempo : 91607
-------------------String Builder---------------------------
17:16:46:806
17:16:46:819
tempo : 13
-------------------String Buffer---------------------------
17:16:46:820
17:16:46:854
tempo: 34