[学习交流] String类的判断功能

* A:String类的判断功能
* boolean equals(Object obj):比较字符串的内容是否相同,区分大小写
* boolean equalsIgnoreCase(String str):比较字符串的内容是否相同,忽略大小写
* boolean contains(String str):判断大字符串中是否包含小字符串
* boolean startsWith(String str):判断字符串是否以某个指定的字符串开头
* boolean endsWith(String str):判断字符串是否以某个指定的字符串结尾
* boolean isEmpty():判断字符串是否为空。
案例:

package com.heima.string;
public class Demo_StringMethod {
public static void main(String[] args) {
//demo1();
//demo2();
String s1 = "heima";
String s2 = "";
String s3 = null;
System.out.println(s1.isEmpty());
System.out.println(s2.isEmpty());
System.out.println(s3.isEmpty()); //java.lang.NullPointerException
}
private static void demo2() {
String s1 = "我爱heima,哈哈";
String s2 = "heima";
String s3 = "baima";
String s4 = "我爱";
String s5 = "哈哈";
System.out.println(s1.contains(s2)); //判断是否包含传入的字符串
System.out.println(s1.contains(s3));
System.out.println("------------------");
System.out.println(s1.startsWith(s4)); //判断是否以传入的字符串开头
System.out.println(s1.startsWith(s5));
System.out.println("------------------");
System.out.println(s1.endsWith(s4)); //判断是否以传入的字符串结尾
System.out.println(s1.endsWith(s5));
}
private static void demo1() {
String s1 = "heima";
String s2 = "heima";
String s3 = "HeiMa";
System.out.println(s1.equals(s2)); //true
System.out.println(s2.equals(s3)); //false
System.out.println("---------------");
System.out.println(s1.equalsIgnoreCase(s2));
System.out.println(s1.equalsIgnoreCase(s3)); //不区分大小写
}
}

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[学习交流] String类的判断功能

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