超星 - 作业2_写出程序运行结果 - 查题吧

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理解构造代码块、静态代码块、构造方法、主方法的执行顺序class Test {private static String name;{System.out.print ("Hello");}static {System.out.print ("How");}Test(){System.out.print ("are");}public static void main(String[] args) {System.out.print("you");Test test = new Test();}}程序运行结果：

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方法重载，并理解int型与char关系class Test{int compute( int a,int b ){return b-a;}String compute(String s1,String s2){return s1+s2;}public static void main(String args[ ]){Test t=new Test ( );char ch1='a';char ch2='b';System.out.println(t.compute(ch1,ch2));}}程序运行结果

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静态成员变量是共享的，非静态成员变量各对象独立class A {int n;static int m;public A(int n,int m) {this.n=n;this.m=m;}}class Test{public static void main(String args[ ]){A a1=new A(10,11);A a2=new A(20,21);System.out.println("a1:n="+a1.n+",m="+a1.m);System.out.println("a2:n="+a2.n+",m="+a2.m);}}程序运行结果：

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接口回调的是子类重写的方法interface Person {double compute(float x,float y);}class Student implements Person {public double compute(float x,float y) {return x-y;}int compute(int x,int y) {return x*y;}}public class Test{public static void main(String args[]) {Person p=new Student();System.out.println( p.compute(30,10));}}程序运行结果：

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非静态方法被子类重写，上转型对象调用的是子类重写的方法，静态方法被子类重写，上转型对象调用的仍然是父类定义的静态方法。class SuperClass {void method() {System.out.println("SuperClass:method");}static void methodStatic() {System.out.println("SuperClass:methodStatic");}}class SubClass extends SuperClass {void method() {System.out.println("SubClass:method");}static void methodStatic() {System.out.println("SubClass:methodStatic");}}public class Test {public static void main(String[] args) {SuperClass a = new SubClass();a.method();a.methodStatic();}}程序运行结果：

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String字符串是不可修改的，它的连接、取子串、替换都会生成新的字符串，原子符串不变public class Test{ public static void main(String args[]){String str="ABCDEF";str.substring(3);str.concat("XYZ");System.out.print(str);}}程序运行结果：

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理解引用类型参数传递class Test{public static void main(String[] args){String s1 = "a";String s2 = "b";show(s1,s2);System.out.println(s1+s2);}public static void show(String s1,String s2){s1 = s1 +"q";s2 = s2 + s1;}}程序运行结果：

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异常处理的执行过程的理解public class Test {public static void main(String[] args) {try {System.out.println(3/0);System.out.println("你好");}catch(ArithmeticException e) {System.out.println("产生算术操作异常");return;}catch(Exception e) {System.out.println("产生异常 ");return;}finally {System.out.println("执行finally块");}System.out.println("程序执行结束！ ");}}程序运行结果：如果除掉程序中两个return语句，程序运行结果：

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理解实现Runnable接口创建的多线程资源共享public class Test {public static void main(String args[]) {Target target =new Target();Thread t1 =new Thread(target);Thread t2 =new Thread(target);t1.start();try{ Thread.sleep(1000);}catch(Exception exp){}t2.start();}}class Target implements Runnable{int i = 10;public void run() {i--;System.out.println("i="+i);}}程序运行结果：

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