package com;

public class GetStringLength {

	public static void main(String[] args) {
		String str="明月几时有，把酒问青天";
		System.out.println(str);
                int strLength=str.length();
                System.out.println("字符串长度为"+strLength);
	}

}

-------------------------------------------------------------------------------------

package com;

public class GetStringLength {

	public static void main(String[] args) {
		
		String str="123 456";
		System.out.println(str);
        int strLength=str.length();
        System.out.println("字符串长度为"+strLength);
        System.out.println("空格算一个字符");
	}

}

-------------------------------------------------------------------------------------------------

null字符串不能使用length()方法