我想要 (yourItems.contains("Gin")) [显示 Gin 的所有饮料] + (yourItems.contains("Vodka")) [显示伏特加的所有饮料] 然后将包含这两种饮料的饮料移动到列表的顶部。
现在,只要我同时选择 Gin 和 Vodka 这两个值,我的应用程序就会崩溃
private List<Drinks> myDrinks = new ArrayList<Drinks>();
private ArrayList<String> yourItems;
...
private void populateDrinkList() {
if (yourItems.contains("Gin")){
myDrinks.add(new Drinks("a"));
myDrinks.add(new Drinks("b"));
myDrinks.add(new Drinks("c"));
myDrinks.add(new Drinks("d"));
myDrinks.add(new Drinks("e"));
if (yourItems.contains("Vodka")) {
Drinks toMoveUp = new Drinks("e");
while (myDrinks.indexOf(toMoveUp) != 0) {
int i = myDrinks.indexOf(toMoveUp);
Collections.swap(myDrinks, i, i-1 );
}
}
}
populateListView();
}
这是饮料类
public class Drinks {
String name = null;
public Drinks(String name){
this.name= name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
登录猫:https://docs.google.com/document/d/1WatONhY7mSsR6Wjs6haZnfNWPSeY0dpusvlbDxnHN5M/edit?usp=sharing
最佳答案
好的,我明白你的代码有什么问题了
在 Drinks
类中将此添加到您的代码中:
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Drinks other = (Drinks) obj;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
在另一个中保持这样:
private void populateDrinkList() {
myDrinks.add(new Drinks("a"));
myDrinks.add(new Drinks("b"));
myDrinks.add(new Drinks("c"));
myDrinks.add(new Drinks("d"));
myDrinks.add(new Drinks("e"));
if (yourItems.contains("Vodka") || yourItems.contains("Gin") ) {
Drinks toMoveUp = new Drinks("e");
while (myDrinks.indexOf(toMoveUp) != 0) {
int i = myDrinks.indexOf(toMoveUp);
Collections.swap(myDrinks, i, i-1 );
}
}
populateListView();
}
关于java - 使用多个 if 值优化数组结果,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20755326/