疯狂java讲义之流程控制与数组

while

package ch4;

/**
 * Created by Jiqing on 2016/11/6.
 */
public class While {
    public static void main(String[] args) {
        int count =0;
        while(count <10) {
            System.out.println(count);
            count++;
        } // 输出0~9
        System.out.println("循环结束");
    }
}

doWhile

package ch4;

/**
 * Created by Jiqing on 2016/11/6.
 */
public class doWhile {
    public static void main(String[] args) {
        int count = 1;
        // 至少执行一次
        do {
            System.out.println(count);
            count++;
        } while (count < 10);// 0~9
        System.out.println("循环结束");
    }
}

For

package ch4;

/**
 * Created by Jiqing on 2016/11/6.
 */
public class For {
    public static void main(String[] args) {
        for(int count = 0; count <10 ;count++) {
            System.out.println(count);
        }
        System.out.println("循环结束！");

        int count = 0;
        for (; count < 10 ;) {
            System.out.println(count);
            count++;
        }

        System.out.println("循环结束！");


    }
}

Continue

package ch4;

/**
 * Created by Jiqing on 2016/11/6.
 */
public class Continue {
    public static void main(String[] args) {
        for (int i = 0;i<5;i++) {
            System.out.println("i的值"+i);
            if (i == 1) {
                continue;
            }
            System.out.println("continue后的语句"+i);

            /**
             i的值0
             continue后的语句0
             i的值1
             i的值2
             continue后的语句2
             i的值3
             continue后的语句3
             i的值4
             continue后的语句4
             */


        }

        outer:
        for (int i = 0;i<5;i++) {
            for (int j = 0;j<3;j++) {
                System.out.println("i的值"+i+"，j的值"+j);
                if (j == 1) {
                    continue outer;
                }
            }
        }
        /**
        i的值0，j的值0
        i的值0，j的值1
        i的值1，j的值0
        i的值1，j的值1
        i的值2，j的值0
        i的值2，j的值1
        i的值3，j的值0
        i的值3，j的值1
        i的值4，j的值0
        i的值4，j的值1
         */
    }
}

Break

package ch4;

/**
 * Created by Jiqing on 2016/11/6.
 */
public class Break {
    public static void main(String[] args) {
        for (int i=0;i<10;i++) {
            System.out.println("i的值是"+i);
            if (i == 2) {
                break; // 跳出该循环
            }
        }

        /**
         i的值是0
         i的值是1
         i的值是2
         */

        outer:
        for (int i = 0;i<5;i++) {
            for (int j = 0;j<3;j++) {
                System.out.println("i的值"+i+"，j的值"+j);
                if (j == 1) {
                    break outer;
                }
            }
        }

        /**
         i的值0，j的值0
         i的值0，j的值1
         */
    }

}

Return

package ch4;

/**
 * Created by Jiqing on 2016/11/6.
 */
public class Return {
    public static void main(String[] args) {
        for (int i = 0;i<5;i++) {
            for (int j = 0;j<3;j++) {
                System.out.println("i的值"+i+"，j的值"+j);
                if (j == 1) {
                    break; // 跳出本次循环
                }
            }
        }

        System.out.println("===================");

        for (int i = 0;i<5;i++) {
            for (int j = 0;j<3;j++) {
                System.out.println("i的值"+i+"，j的值"+j);
                if (j == 1) {
                    return; // 直接结束循环,相当于break outer
                }
            }
        }
    }
}
//        i的值0，j的值0
//        i的值0，j的值1
//        i的值1，j的值0
//        i的值1，j的值1
//        i的值2，j的值0
//        i的值2，j的值1
//        i的值3，j的值0
//        i的值3，j的值1
//        i的值4，j的值0
//        i的值4，j的值1
//        ===================
//        i的值0，j的值0
//        i的值0，j的值1

数组

package ch4;

/**
 * Created by Jiqing on 2016/11/9.
 */
public class Array {
    public static void main(String[] args) {
        int[] intArr;
        intArr = new int[]{5,4,8,20};
        Object[] objArr;
        objArr = new String[]{"Java","李刚"};

        // 定义和初始化同时完成
        int[] a = {5,6,7,9};
        System.out.println(a[1]); // 6
        System.out.println(intArr[1]); // 4
        System.out.println(objArr[1]); // 李刚

        // 循环输出
        for(int i = 0;i<a.length;i++) {
            System.out.println(a[i]);
        }

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

        for (int i : a) {
            System.out.println(i);
        }
    }
}