System.out.println("5+5="+5+5);    //5+5=55

System.out.println('*' + '\t' +'*');  //93
System.out.println("*" + '\t' +'*');  //* *

public class TestApp {@Testpublic void test() {int i1 = 10,i2 = 20;int i = i1++;System.out.print("i="+i);   //i=10System.out.println("i="+i1); //i=11
i = ++i1;System.out.print("i="+i);      //i=12System.out.println("i="+i1); //i=12
i = i2--;System.out.print("i="+i);     //i=20System.out.println("i="+i2); //i=19
i = --i2;System.out.print("i="+i);    //i=18System.out.println("i="+i2);//i=18
    }
}                

public class TestApp {@Testpublic void test() {boolean b1 = false;// 区分好==和=的区别。if (b1 = true)System.out.println("结果为真");elseSystem.out.println("结果为假");}
}
结果为真

public class TestApp {@Testpublic void test() {int i = 1;i *= 0.1;System.out.println(i);//0i++;System.out.println(i);//1
}
}

@Testpublic void test() {short s = 3; s=s+2;  //编译服务通过s+=2;    //编译成功
}

@Testpublic void test() {int x = 1;int y=1;if(x++==2 & ++y==2){x =7;}System.out.println("x="+x+",y="+y);   //x=2,y=2
x = 1;y = 1;if(x++==2 && ++y==2){x =7;}System.out.println("x="+x+",y="+y);  //x=2,y=1
        x = 1;y = 1;if(x++==1 | ++y==1){x =7;}System.out.println("x="+x+",y="+y);  //x=7,y=2
        x = 1;y = 1;if(x++==1 || ++y==1){x =7;}System.out.println("x="+x+",y="+y);   //x=7,y=1}

public static void main(String[] args){int m = 12;int n = 5;System.out.println("m:" + m + " n:" + n);//方法一：提供一个临时变量。//int temp = m;//       m = n;//       n = temp;//System.out.println("m:" + m + " n:" + n);//方法二：当m和n较大时，有可能出现精度损失//m = m + n;//m = 12 + 5;//n = m - n;//n = 17 - 5;//m = m - n;//m = 17- 12//System.out.println("m:" + m + " n:" + n);//方法三：优点：没有上面两种方法的缺点。 缺点：难！m = m ^ n;n = m ^ n;//(m ^ n) ^ n == mm = m ^ n;//(m ^ n) ^ m == nSystem.out.println("m:" + m + " n:" + n);}

public static void main(String[] args){//问题：//60  手动的方式，从控制台输出60的十六进制。int i = 61;//自动调用Integer类现成的方法String binary = Integer.toBinaryString(i);System.out.println(binary);String hex = Integer.toHexString(i);System.out.println(hex);/*char c = 'a';char c1 = (char)(c + 2);System.out.println(c1);//c*/int j = i & 15;//获取到i的最低4位对应的值。String k1 = (j <= 9)? j + "" : (char)(j - 10 + 'a') + ""; //System.out.println(k1);
i = i >> 4;int z = i & 15;String k2 = (z <= 9)? z + "" : (char)(z - 10 + 'a') + "";System.out.println(k2 + k1);}