Java 中 Reader ready()方法，带示例
原文:https://www . geesforgeks . org/reader-reader-ready-in-method-in-Java-with-examples/
Java 中 Reader 类的 ready() 方法用来检查这个 Reader 是否准备好被读取。它返回一个布尔值，表示读取器是否准备好了。
语法:
public void ready()
参数:该方法不接受任何参数
返回值:这个方法返回一个布尔值，它告诉这个阅读器是否准备好被读取。如果它准备好了，它就会变成真的。否则返回假。
异常:如果输入输出时出现错误，该方法抛出异常。
下面的方法说明了 ready()方法的工作原理:
程序 1:
// Java program to demonstrate
// Reader ready() method
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
try {
String str = "GeeksForGeeks";
// Create a Reader instance
Reader reader
= new StringReader(str);
// Check if the Reader is
// ready to be read using ready()
System.out.println("Is Reader ready "
+ "to be read: "
+ reader.ready());
// Get the character
// to be read from the stream
int ch;
// Read the first 5 characters
// to this reader using read() method
// This will put the str in the stream
// till it is read by the reader
for (int i = 0; i < 5; i++) {
ch = reader.read();
System.out.println("\nInteger value "
+ "of character read: "
+ ch);
System.out.println("Actual "
+ "character read: "
+ (char)ch);
}
reader.close();
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出:
Is Reader ready to be read: true
Integer value of character read: 71
Actual character read: G
Integer value of character read: 101
Actual character read: e
Integer value of character read: 101
Actual character read: e
Integer value of character read: 107
Actual character read: k
Integer value of character read: 115
Actual character read: s
程序二:
// Java program to demonstrate
// Reader ready() method
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
try {
String str = "GeeksForGeeks";
// Create a Reader instance
Reader reader
= new StringReader(str);
reader.close();
// Check if the Reader is
// ready to be read using ready()
System.out.println("Is Reader ready "
+ "to be read: "
+ reader.ready());
// Get the character
// to be read from the stream
int ch;
// Read the first character
// to this reader using read() method
// This will put the str in the stream
// till it is read by the reader
ch = reader.read();
System.out.println("\nInteger value "
+ "of character read: "
+ ch);
System.out.println("Actual "
+ "character read: "
+ (char)ch);
reader.close();
}
catch (Exception e) {
System.out.println(e);
}
}
}
输出:
java.io.IOException: Stream closed
参考:https://docs . Oracle . com/javase/9/docs/API/Java/io/reader . html # ready–
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