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Java SE 7中, 整数类型(byte, short, int以及long) 也可以使用二进制数系来表示。要指定一个二进制字面量，可以给二进制数字添加前缀 0b 或者 0B。下面的示例展示了一些二进制字面量：
// 一个8位的'byte'值:
byte aByte = (byte)0b00100001;
// 一个16位的'short'值:
short aShort = (short)0b1010000101000101;
// 几个32位的'int'值:
int anInt1 = 0b10100001010001011010000101000101;
int anInt2 = 0b101;
int anInt3 = 0B101; // B可以是大写或者小写.
// 一个64位的'long'值.注意"L"后缀:
long aLong = 0b1010000101000101101000010100010110100001010001011010000101000101L;
相比于十六进制或者八进制，二进制字面量可以使数据之间的关系更加清晰。比如, 下面数组中的每个后续数字是按位旋转的：
public static final int[] phases = {
0b00110001,
0b01100010,
0b11000100,
0b10001001,
0b00010011,
0b00100110,
0b01001100,
0b10011000
}
十六进制中, 数字之间的关系并不清晰:
public static final int[] phases = {
0x31, 0x62, 0xC4, 0x89, 0x13, 0x26, 0x4C, 0x98
}
可以在代码中使用二进制字面量常量来验证一个规范文档, 比如一个针对假设的8位微处理器的模拟器:
public State decodeInstruction(int instruction, State state) {
if ((instruction & 0b11100000) == 0b00000000) {
final int register = instruction & 0b00001111;
switch (instruction & 0b11110000) {
case 0b00000000: return state.nop();
case 0b00010000: return state.copyAccumTo(register);
case 0b00100000: return state.addToAccum(register);
case 0b00110000: return state.subFromAccum(register);
case 0b01000000: return state.multiplyAccumBy(register);
case 0b01010000: return state.divideAccumBy(register);
case 0b01100000: return state.setAccumFrom(register);
case 0b01110000: return state.returnFromCall();
default: throw new IllegalArgumentException();
}
} else {
final int address = instruction & 0b00011111;
switch (instruction & 0b11100000) {
case 0b00100000: return state.jumpTo(address);
case 0b01000000: return state.jumpIfAccumZeroTo(address);
case 0b01000000: return state.jumpIfAccumNonzeroTo(address);
case 0b01100000: return state.setAccumFromMemory(address);
case 0b10100000: return state.writeAccumToMemory(address);
case 0b11000000: return state.callTo(address);
default: throw new IllegalArgumentException();
}
}
}
可以使用二进制字面量增强位图的可读性:
public static final short[] HAPPY_FACE = {
(short)0b0000011111100000,
(short)0b0000100000010000,
(short)0b0001000000001000,
(short)0b0010000000000100,
(short)0b0100000000000010,
(short)0b1000011001100001,
(short)0b1000011001100001,
(short)0b1000000000000001,
(short)0b1000000000000001,
(short)0b1001000000001001,
(short)0b1000100000010001,
(short)0b0100011111100010,
(short)0b0010000000000100,
(short)0b0001000000001000,
(short)0b0000100000010000,
(short)0b0000011111100000
}