Java try/catch 异常处理的问题

Question

public static void main(String[] args) {
        System.out.println(test(null)+","+test("")+","+test("1"));
    }

    @SuppressWarnings("finally")
    private static int test(String str) {
        try{
            return str.charAt(0)-'0';
        }catch(NullPointerException e){
            e.printStackTrace();
            return 1;
        }catch(RuntimeException e){
            e.printStackTrace();
            return 2;
        }catch(Exception e){
            e.printStackTrace();
            return 3;
        }finally{//finally  永远被执行
            return 4;
        }
            
    }

求输出结果及解释，本人菜鸟，见笑了！

 

Answer 1

java.lang.NullPointerException
at com.dream.model.ExceptionTest.test(ExceptionTest.java:17)
at com.dream.model.ExceptionTest.main(ExceptionTest.java:11)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(String.java:695)
at com.dream.model.ExceptionTest.test(ExceptionTest.java:17)
at com.dream.model.ExceptionTest.main(ExceptionTest.java:11)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
4,4,4

第一个方法调用会报NullPointerException
第二个方法调用会报StringIndexOutOfBoundsException
第三个方法运行正常

因为有finally块，所以不论前面的运行结果是什么，都会返回4，所以会看到4，4，4这样的输出结果。