1.for
package com.yfs.javase;
import java.awt.Color;
import java.util.Calendar;
import java.util.HashSet;
import java.util.Set;
@SuppressWarnings("all")
public class ForDemo {
/**
* @param args
*/
public static void main(String[] args) {
//useArray();
//useSet();
boxTest();
//
// Calendar cal = Calendar.getInstance();
// int year = cal.get(Calendar.YEAR);
}
@Deprecated
public static void boxTest() {
int a = 10;
Integer oInt = new Integer(a);
Integer o2 = a;//自动装箱
System.out.println("o2 = " + o2);
int b = o2 + 1; // 自动拆箱
System.out.println("b = " + b);
}
public static void useSet() {
Set<String> set = new HashSet<String>();
set.add("eee");
set.add("ccc");
set.add("aaa");
set.add("bbb");
set.add("yyy");
for (Object s : set) {
System.out.print((String)s + " ");
}
}
//增强for
public static void useArray() {
int[] a = {45,23,11,68,28,65,9,2,18,97};
for(int i : a) {
System.out.print(i + " ");
}
}
@Override//元数据
public String toString() {
// TODO Auto-generated method stub
return super.toString();
}
}
2.静态导入
package com.yfs.javase;
import static java.lang.Math.PI;//静态导入
import static java.lang.Math.sqrt;
public class StaticImport {
/**
* @param args
*/
public static void main(String[] args) {
//staticTest();
paramTest("java",2,3);
// paramTest(2,3,4,5,6);
// paramTest(10,20,30,40);
// paramTest(new int[]{45,22,61,32,78,15,24,63,98});
}
//变长参数 1.只能有一个 2.类型没有限制 3.可以传其他参数 必须在变长参数之前
public static void paramTest(String name, int ... a /*, Object...obj*/) {
int sum = 0;
System.out.println("call paramTest(int ... a) ...");
for (int i = 0; i < a.length; i++) {
sum += a[i];
}
System.out.println("sum = " + sum);
}
public static void paramTest(int a,int b) {
int sum = a + b;
System.out.println("sum = " + sum);
}
public static void staticTest() {
double area = Math.PI * 2 *2;
area = PI* 4 * 4;
area = PI* 6 * 6;
double result = Math.sqrt(16);
result = sqrt(81);
}
}
3.Thread1继承 Thread
package com.yfs.javase.thread;
public class Thread1 extends Thread {
public void test() {
while( true ) {
System.out.println("bbbbbbbbbb");
}
}
@Override
public void run() {//覆盖父类run方法
while( true ) {
System.out.println(Thread.currentThread().getName() + "bbbbbbbbbb");
}
}
}
4.Thread2实现Runnable接口
package com.yfs.javase.thread;
public class Thread2 implements Runnable {
@Override
public void run() {
while(true) {
System.out.println(Thread.currentThread().getId() + "ccccccccccc");
}
}
}
5.Thread1测试（单线程）
package com.yfs.javase.thread;
public class ThreadDemo1 {
public static void main(String[] args) {
Thread1 th1 = new Thread1();
th1.test();
for (int i = 0;; i++) {
System.out.println("aaaaaaaaaaa");
}
//System.out.println("执行结束...");
}
}
6.Thread2测试（多、线程启动）
package com.yfs.javase.thread;
public class ThreadDemo2 {
public static void main(String[] args) {
//继承Thread类
Thread1 th1 = new Thread1();
th1.start();//调用父类start方法
//实现runnabel接口
Thread2 r2 = new Thread2();
Thread th2 = new Thread(r2);
th2.start();
for (int i = 0;; i++) {
System.out.println("aaaaaaaaaaa");
}
//System.out.println("执行结束...");
}
}
7.currentThread
package com.yfs.javase.thread;
public class ThreadDemo3 {
// 线程启动
public static void main(String[] args) throws Exception {
// 继承Thread类
Thread1 th1 = new Thread1();
//th1.run();//普通方法调用 线程的执行代码============?????注意
//启动
th1.setName("逗你玩 ");
th1.start();
//接口
Thread th2 = new Thread(new Thread2());
th2.start();
Thread.currentThread().setPriority(Thread.MAX_PRIORITY);===========
for (int i = 0;; i++) {
Thread.sleep(1);
System.out.println( Thread.currentThread().getPriority() + " aaaaaaaaaaa");
}
}
}