java中比较字符串

本文做equals(),equalsIgnoreCase()和==三种方式的比较

import java.util.StringTokenizer;
class Play
{
    public static void main(String[] args)
    {
        String s1 = new String("I am a student");
        String s2 = new String("I am a student");
        String s3 = new String("I AM A STUDENT");
        String s4 = s1;

        boolean b1 = (s1 == s2);
        boolean b2 = (s1 == s4);
        boolean b3 = s1.equals(s2);
        boolean b4 = s1.equals(s3);
        boolean b5 = s1.equalsIgnoreCase(s2);
        boolean b6 = s1.equalsIgnoreCase(s3);

        System.out.println("s1 == s2: " + b1);
        System.out.println("s1 == s4: " + b2);
        System.out.println("s1 equals(s2): "+ b3);
        System.out.println("s1 equals(s3):"+ b4);
        System.out.println("s1 eqnalsIgnoreCase(s2): "+ b5);
        System.out.println("s1 equalsIgnoreCase(s3): "+ b6);
    }
}

编译，运行结果:


“==”比较的是内存的位置，不适宜比较字符串，但可以用来比较整型等。equals()比较的字符串内容必须完全一样，equalsIgnoreCase()在忽略大小写的情况下比较字符串。以下附上内存分配的图片