問題描述

private String getMainTitle(List<String> bs){ for(String b:bs){if (b.equals('GOOD'){ return 'string';} }return null;}private String getMainTitle(String b){ if (b.equals('GOOD'){return 'string'; }return null;}public String getTitleFromString(String b){ return getMainTitle(b);}public String getTitleFromList(List<String> bs){return getMainTitle(bs);}

請(qǐng)問怎樣在JAVA寫一個(gè)含未知類的參數(shù)的方法?

希望寫一個(gè)方法能替代getTitleFromString和getTitleFromList , 比如:

public String getTitleFromList(T<?> t){return getMainTitle(t);}

但我的語法有誤, 請(qǐng)問該怎樣改寫?

問題解答

public String <T> getMainTitle(T obj){ if(Map.class.isAssignableFrom(obj.getClass())){((Map<?, ?>) data).forEach((k, v) -> { if (v.equals('GOOD')) {return 'string'; } });} else if(Vector.class.isAssignableFrom(obj.getClass())){for(String b:bs){ if (b.equals('GOOD')) {return 'string'; }} } else if ( b.equals('GOOD') ){return 'string'; } return null;}回答2：

private String getMainTitle(List<String> bs){for(String b:bs){ if (b.equals('GOOD')) {return 'string'; }}return null; } private String getMainTitle(String b){if (b.equals('GOOD')) { return 'string';}return null; } public String getTitleFrom(String b){return getMainTitle(b); } public String getTitleFrom(List<String> bs){return getMainTitle(bs); }回答3：

這樣可行

private <T> T getMainTitle(T t){ if (t.equals('GOOD')){return (T)'string'; } return null;}public <T> T getTitleFromString(T t){ return getMainTitle(t);}回答4：

// Object...objs相當(dāng)一個(gè)Object[]數(shù)組,用來當(dāng)做參數(shù)，表示有未知個(gè)參數(shù)傳入，甚至可以不傳參！public String getMainTitle(Object...objs) { for (Object obj : objs) { if(obj.toString().equals('GOOD')){ return 'string'; } } return null;}// 使用public void static main(String[] args) { getMainTitle(); getMainTitle('sdfds', 'Goods', 'GOOD'); getMainTitle(true, 'GOOD'); getMainTitle(111,1111);}