#trim() 清空多余的空格。獲取句子中，把句子前的若干個空格、或句子后的若干個空格清空掉。輸出沒有前后空格的句子，例外的是句子的單詞間的空格保持原狀態。 ##用法 Sting name= EditText.getText().toString().trim(); ##例子 * * * * * 情況一 ~~~ /** * 提交書籍信息 */ private class Submit implements View.OnClickListener { @Override public void onClick(View view) { String name = bookNmae.getText().toString().trim(); String isbn = bookIsbn.getText().toString().trim(); //使用 trim() String publishingHouse = bookPublishingHouse.getText().toString().trim(); String anthor = bookAnthor.getText().toString().trim(); boolean judgmentNull = JudgmentNull(name, isbn, publishingHouse, anthor); if (judgmentNull) { Toast.makeText(AddBookActivity.this, name+"\n"+isbn+"\n"+publishingHouse+"\n"+anthor, Toast.LENGTH_SHORT).show(); }else{ Toast.makeText(AddBookActivity.this, "輸入的內容不能為空", Toast.LENGTH_SHORT).show(); } } } ~~~ ###效果  * * * * * 情況二 ~~~ /** * 提交書籍信息 */ private class Submit implements View.OnClickListener { @Override public void onClick(View view) { String name = bookNmae.getText().toString().trim(); String isbn = bookIsbn.getText().toString(); //不使用 trim() String publishingHouse = bookPublishingHouse.getText().toString().trim(); String anthor = bookAnthor.getText().toString().trim(); boolean judgmentNull = JudgmentNull(name, isbn, publishingHouse, anthor); if (judgmentNull) { Toast.makeText(AddBookActivity.this, name+"\n"+isbn+"\n"+publishingHouse+"\n"+anthor, Toast.LENGTH_SHORT).show(); }else{ Toast.makeText(AddBookActivity.this, "輸入的內容不能為空", Toast.LENGTH_SHORT).show(); } } } ~~~ ###效果