验证用于搜索arrayLists

Question

您好我创建了搜索数组列表的代码，如果没有找到任何内容，我需要能够打印一行。

            for (int i = 0; i < trackNum.size(); i++) { //looping arrayList trackNum
            if(trackNum.get(i).equals(trackNumber)){ //searching for matches to trackNumber
                System.out.println(trackNum.get(i) + ": " + name.get(i) + " " + duration.get(i)); //printing out the matches            
            } else{
                System.out.println("Not Tracks Found for " + trackNumber);
            }
        }

目前它没有打印出else行，它只是留空。

Answer 1

你应该只打印＆＃34;未找到＆＃34;迭代整个列表后的消息：

        boolean found = false;
        for (int i = 0; i < trackNum.size(); i++) { //looping arrayList trackNum
            if(trackNum.get(i).equals(trackNumber)){ //searching for matches to trackNumber
                System.out.println(trackNum.get(i) + ": " + name.get(i) + " " + duration.get(i)); //printing out the matches            
                found = true;
                break;
            }
        }   
        if (!found) {
            System.out.println("Not Tracks Found for " + trackNumber);
        } 

Answer 2

最好使用contains和indexOf进行搜索：

    if (trackNum.contains(trackNumber)) {
        int i = trackNum.indexOf(trackNumber);
        System.out.println(trackNum.get(i) + ": " + name.get(i) + " " + duration.get(i)); //printing out the matches            
    } else {
        System.out.println("Not Tracks Found for " + trackNumber);
    }