Java集合的遍历方法

import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;

import org.junit.Test;

public class TestIterator {
//迭代器遍历
@Test
public void test1() {
Collection col = new ArrayList();
col.add(123);
col.add(new String("AAA"));
col.add(new Date());
col.add(new TestObject1("MM"));
col.add(new TestObject2("GG"));

Iterator iterator = col.iterator();
while(iterator.hasNext()) {
System.out.println(iterator.next());
}
}

//foreach遍历
@Test
public void test2() {
Collection col = new ArrayList();
col.add(123);
col.add(new String("AAA"));
col.add(new Date());
col.add(new TestObject1("MM"));
col.add(new TestObject2("GG"));

for (Object obj : col) {
System.out.println(obj);
}
}

//foreach遍历再举例
@Test
public void test3() {
String[] str = new String[]{"AA","BB","DD"};
for (String s : str) {
System.out.println(s);
}
}

//注意：foreach遍历
@Test
public void test4() {
String[] str = new String[]{"AA","BB","DD"};
for (String s : str) {
s = "MM";//此处的s是定义的局部变量，其值的修改不会对str本身造成影响
}
for (String s : str) {
System.out.println(s);
}
/*
* 结果：
* AA
* BB
* DD
*/
}
}