importjava.util.Objects;publicclassSafeStringComparison{publicstaticvoidmain(String[]args){Stringstr1=null;Stringstr2="Hello";// 使用 Objects.equals() 比较if(Objects.equals(str1,str2)){System.out.println("str1 is equal to str2");}else{System.out.println("str1 is not equal to str2");/...
if(str.equals("")){System.out.println("The string is equal to an empty string.");} 1. 2. 3. 这段代码的意思是,如果str与空字符串相等,则输出 “The string is equal to an empty string.”。 结语 通过以上步骤,你应该能够正确地实现 Java 中的String与null比较。记住,始终检查变量是否为null,...
if(s==null||s==""); 注意,s == null这个判断是有必要存在的,如果String类型为null,进行equals(String)或length()等操作会抛出java.lang.NullPointerException。而且s==null的顺序必须出现在前面,不然同样会抛出java.lang.NullPointerException。
* @return if the argument is null, then a string equal to * "null"; otherwise, the value of * obj.toString() is returned. * @see java.lang.Object#toString() */ public static String valueOf(Object obj) { return (obj == null) ? "null" : obj.toString(); } 从上面的源码可以很...
答:String类的常用方法包括length(),charAt(),concat(),substring(),indexOf(),equals(),compareTo()等。 4.问:String和StringBuilder/StringBuffer的区别是什么? 答:String是不可变对象,每次修改都会生成一个新的String对象;StringBuilder/StringBuffer是可变对象,可以直...
string.equals(String str) equals() Arguments Theequals()method takes a single argument. str- the string to be compared equals() Return Value returns trueif the strings are equal returns falseif the strings are not equal returns falseif thestrargument isnull ...
The Java language provides special support for the string concatenation operator ( + ), and for conversion of other objects to strings. For additional information on string concatenation and conversion, see The Java™ Language Specification. Unless otherwise noted, passing a null argument to a co...
7. public static String trimToEmpty(String str) 去掉字符串两端的控制符(control characters, char <= 32) ,如果变为 null 或 "" ,则返回 "" 下面是示例: 12345678StringUtils.trimToEmpty(null) = ""StringUtils.trimToEmpty("") = ""StringUtils.trimToEmpty(" ") = ""StringUtils.trimToEmpty(" ...
} public void setName(String name) { this.name = name; } public Person(String name){ this.name = name; } public boolean equals(Object object){ if(object instanceof Person){ Person p = (Person) object; if(p.getName() == null || name ==...
publicfinalclassStringimplementsjava.io.Serializable, Comparable<String>, CharSequence {// 在JDK1.8中String的值使用char[]数组保存privatefinalcharvalue[];// 使用私有成员变量hash来缓存String的哈希值privateinthash;// Default to 0// 构造方法publicString(String original){this.value = original.value;this....