全局变量和局部变量重复之this.name.toString());Exception in thread "main" java.lang.NullPointerException
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public class swap {
String name;//全局变量
public static void main(String[] args) {
new swap();
}
public swap() {
String name = "wowo";//局部变量
System.out.println(this.name.toString());
}
String name;//全局变量
public static void main(String[] args) {
new swap();
}
public swap() {
String name = "wowo";//局部变量
System.out.println(this.name.toString());
}
}
=========运行结果========
Exception in thread "main" java.lang.NullPointerException
at swap.<init>(swap.java:8)
at swap.main(swap.java:4)
==========解答:
this.name作为全局变量默认为NULL,NULL对象.ToStrign();就会出现错误!
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