package com.lk.B;public class Test1 {public static void main(String[] args) {// TODO Auto-generated method stubTest1 t = new Test1();t.first();}public void first(){int i = 5;Value v = new Value();v.i = 25;second(v,i);System.out.println(v.i);}public void second(Value v , int i){i = 0;v.i = 20;Value val = new Value();v = val;System.out.println(v.i+" "+i);}
}class Value{public int i = 15;
}

package com.lk.B;public class Test2 {public static void main(String[] args) {// TODO Auto-generated method stubboolean test = true;System.out.println(test);test(test);System.out.println(test);}public static void test(boolean test){test = !test;System.out.println(test);}}

true
false
true

package com.lk.B;public class Test2 {public static void main(String[] args) {// TODO Auto-generated method stubStringBuffer sb = new StringBuffer("Hello");System.out.println(sb);test(sb);System.out.println(sb);}public static void test(StringBuffer sb){sb.append(",World!");}}

Hello
Hello,World!

package com.lk.B;public class Test2 {public static void main(String[] args) {// TODO Auto-generated method stubString s = "Hello";System.out.println(s);test(s);System.out.println(s);}public static void test(String s){s = "World";}}

Hello
Hello

package com.lk.B;import java.io.FileOutputStream;
import java.io.IOException;public class Test2 {public static void main(String[] args) {// TODO Auto-generated method stubFileOutputStream fos = null;try {fos = new FileOutputStream("FileName.txt");fos.write("字符串写入文件".getBytes());} catch (IOException e) {// TODO Auto-generated catch block
            e.printStackTrace();} finally{try {fos.close();} catch (IOException e) {// TODO Auto-generated catch block
                e.printStackTrace();}}}
}

package com.lk.B;public class Test3 {public static void main(String[] args) {// TODO Auto-generated method stubint a = 256;//2,4,8,16,32,64,128,256...System.out.println((a-1)&a);//输出0
    }}