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Java 文件处理

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Java 如何做

加两个数字 统计单词 反转字符串 数组元素求和 将字符串转换为数组 对数组进行排序 计算数组平均值 查找最小元素 ArrayList 循环 HashMap 循环 遍历枚举 长方形面积 偶数或奇数 正数或负数 平方根 随机数

Java 参考

Java 参考 Java 关键字
assert abstract boolean break byte case catch char class continue default do double else enum exports extends final finally float for if implements import instanceof int interface long module native new package private protected public return requires short static super switch synchronized this throw throws transient try var void volatile while
Java 字符串方法
charAt() codePointAt() codePointBefore() codePointCount() compareTo() compareToIgnoreCase() concat() contains() contentEquals() copyValueOf() endsWith() equals() equalsIgnoreCase() format() getBytes() getChars() hashCode() indexOf() isEmpty() join() lastIndexOf() length() matches() offsetByCodePoints() regionMatches() replace() replaceAll() replaceFirst() split() startsWith() subSequence() substring() toCharArray() toLowerCase() toString() toUpperCase() trim() valueOf()
Java 数学方法
abs() acos() addExact() asin() atan() atan2() cbrt() ceil() copySign() cos() cosh() decrementExact() exp() expm1() floor() floorDiv() floorMod() getExponent() hypot() IEEEremainder() incrementExact() log() log10() log1p() max() min() multiplyExact() negateExact() nextAafter() nextDown() nextUp() pow() random() rint() round() scalb() signum() sin() sinh() sqrt() subtractExact() tan() tanh() toDegrees() toIntExact() toRadians() ulp()
Java 输出方法
print() printf() println()
Java 数组方法
compare() equals() sort() fill() length
Java ArrayList 方法
add() addAll() clear() clone() contains ensureCapacity() forEach() get() indexOf() isEmpty() iterator() lastIndexOf() listIterator() remove() removeAll() removeIf() replaceAll() retainAll() set() size() sort() spliterator() subList() toArray() trimToSize()
Java LinkedList 方法
add() addAll() clear() clone() contains forEach() get() getFirst() getLast() indexOf() isEmpty() iterator() lastIndexOf() listIterator() remove() removeAll() removeFirst() removeIf() removeLast() replaceAll() retainAll() set() size() sort() spliterator() subList() toArray()
Java HashMap 方法
clear() clone() compute() computeIfAbsent() computeIfPresent() containsKey() containsValue() entrySet() forEach() get() getOrDefault() isEmpty() keySet() merge() put() putAll() putIfAbsent() remove() replace() replaceAll() size() values()
Java Scanner 方法
close() delimiter() findInLine() findWithinHorizon() hasNext() hasNextBoolean() hasNextByte() hasNextDouble() hasNextFloat() hasNextInt() hasNextLine() hasNextLong() hasNextShort() locale() next() nextBoolean() nextByte() nextDouble() nextFloat() nextInt() nextLine() nextLong() nextShort() radix() reset() useDelimiter() useLocale() useRadix()
Java 迭代器方法 Java 错误 & 异常

Java 示例

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Java 声明多个变量

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声明多个变量

要声明多个**相同类型**的变量，可以使用逗号分隔列表

示例

而不是写

int x = 5;
int y = 6;
int z = 50;
System.out.println(x + y + z);

你可以简单地写

int x = 5, y = 6, z = 50;
System.out.println(x + y + z);

尝试一下 »

一个值赋给多个变量

你也可以在一行中将**相同的值**赋给多个变量

示例

int x, y, z;
x = y = z = 50;
System.out.println(x + y + z);

尝试一下 »


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