LX【300ｘ75】


オブジェクト 配列


コード 

public class ObjArrary {

	public static void main(String[] args) {

		System.out.println("Start");

		//
		System.out.println("------------------------");
		
		
		//
		String strArrary[] = new String[3];
		
		System.out.println("strArrary.length -> " + strArrary.length);
		
		strArrary[0] = "0";

		strArrary[2] = "22";

		System.out.println("strArrary[0] -> " + strArrary[0]);
		System.out.println("strArrary[1] -> " + strArrary[1]);	//NULL
		System.out.println("strArrary[2] -> " + strArrary[2]);

		System.out.println("strArrary[0].length() -> " + strArrary[0].length());
		System.out.println("strArrary[2].length() -> " + strArrary[2].length());
		
		//NULL ERROR
		System.out.println("strArrary[1].length() -> " + strArrary[1].length());
		
		//
		System.out.println("------------------------");
		
		System.out.println("End");
		
	}
}


結果 

Start
------------------------
strArrary.length -> 3
strArrary[0] -> 0
strArrary[1] -> null
strArrary[2] -> 22
strArrary[0].length() -> 1
strArrary[2].length() -> 2
java.lang.NullPointerException at ObjArrary.main(ObjArrary.java:44)
Exception in thread "main"

 

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